positron

Paper	Title	Other Keywords	Page
TUZACH01	Positron Source Options for Linear Colliders	gun, focusing, synchrotron, acceleration	69
	K. Floettmann DESY, Hamburg
	Linear colliders require sources delivering particle intensities much higher than sources for storage rings and even several orders of magnitude larger than the SLC positron source, the highest intensity positron source operated so far. A fundamental limitation for the intensity of a positron source is set by the thermal stress in the target. Besides improvements of conventional positron sources, i.e. sources where an electron beam creates electron position pairs in an electromagnetic cascade, new concepts based on the direct conversion of gamma radiation offer possibilities for increased particle intensities. In these sources the hard gamma radiation has to be produced either in an undulator or by backscattering of laser light off an electron beam. An additional advantage of gamma radiation based sources is the possibility to produce polarized positrons. The talk will give an overview of the developments of high intensity unpolarized and polarized positron sources for linear colliders.
	Video of talk
	Transparencies
TUZACH02	Ultra-high Gradient Compact Accelerator Developments	gun, injection, focusing, plasma	74
	G.J.H. Brussaard, M.J. Van der Wiel TUE, Eindhoven
	Continued development of relatively compact, although not quite 'table-top', lasers with peak powers in the range up to 100 TW has enabled laser-plasma-based acceleration experiments with amazing gradients of up to 1 TV/m. In order to usefully apply such gradients to 'controlled' acceleration, various hurdles need to be overcome. The main one is that of well-synchronized injection into a sub-mm to micron wavelength plasma wave. The talk will describe the various physics regimes of laser wakefield acceleration, and the two classes of experiments being pursued. One is that of atmospheric-density plasmas, non-linear wakefields with extreme gradients (hundreds of GV/m)and 'internal injection' of few-femtosecond electron bunches. A second class involves modest-density plasmas,wakefields of order 1 GV/m and external injection of (sub)-ps bunches. The state-of-the-art of these experiments will be covered, including the progress on plasma waveguiding of TW pulses over many diffraction lengths. The talk will also provide an outlook for the coming few years. This part includes proposed schemes for improvements in the area of injection, such as 'all-optical' injection and injection based on GV/m 'pulsed-DC' photoguns.
	Video of talk
	Transparencies
TUZBCH01	Beam Quality Preservation in the CERN PS-SPS Complex	gun, focusing, plasma, synchrotron	78
	G. Arduini CERN, Geneva
	The LHC will require beams of unprecedented transverse and longitudinal brightness. Their production imposes tight constraints on the emittance growth in each element of the LHC injector chain, namely the PS-SPS Accelerator Complex. The problems encountered at the different stages of the acceleration in the complex span a wide range of topics, such as injection matching, RF gymnastics, space charge, transverse and longitudinal single- and coupled-bunch instabilities, and electron cloud effects. The measurement techniques developed and applied to identify and study the various sources of emittance dilution to the high precision required for the LHC beams and the solutions found to control such phenomena are illustrated.
	Video of talk
	Transparencies
TUZBCH02	Beam Dynamics Challenges for Future Circular Colliders	gun, focusing, plasma, synchrotron	83
	F. Zimmermann CERN, Geneva
	The luminosity of circular colliders rises with the beam intensity, until some limit is encountered, mostly due to head-on and long-range beam-beam interaction, due to electron cloud, or due to conventional impedance sources. These limitations can be alleviated, if not overcome, by a proper choice of beam parameters and by dedicated compensation schemes. Examples include the alternating crossing at several interaction points, electromagnetic wires, super-bunches, electron lenses, clearing electrodes, and nonlinear collimation. I illustrate the benefit from such mitigating measures for the Tevatron, the LHC, the LHC Upgrade, the VLHC, the super e+e- factories, or other projects, and I describe related research efforts at FNAL, KEK, BNL and CERN.
	Video of talk
	Transparencies
TUXLH01	Machine Protection Issues and Strategies for the LHC	gun, focusing, plasma, synchrotron	88
	R. Schmidt, J. Wenninger CERN, Geneva
	For nominal beam parameters at 7 TeV/c, each of the two LHC proton beams has a stored energy of 350 MJ threatening to damage accelerator equipment in case of uncontrolled beam loss. Since the beam dump blocks are the only element of the LHC that can withstand the impact of the full beam, it is essential for the protection of the LHC that the beams are properly extracted onto the dump blocks in case of emergency. The time constants for failures leading to beam loss extend from 100 microseconds to few seconds. Several protection systems are designed to ensure safe operation, such as beam instrumentation, collimators and absorbers, and magnet protection. Failures must be detected at a sufficiently early stage and transmitted to the beam interlock system that triggers the beam dumping system. The strategy for the protection of the LHC will be illustrated starting from some typical failures.
	Video of talk
	Transparencies
TUXLH02	HERA Performance Upgrade: Achievements and Plans for the Future	gun, focusing, plasma, luminosity	93
	M.G. Minty DESY, Hamburg
	Having surpassed the design luminosity of 1.5 x 1031/cm2s already in 1997, an ambitious upgrade of the HERA proton-lepton collider was undertaken in 2000/2001 to provide both higher luminosity and longitudinally polarized lepton beams in the colliding beam experiments, H1 and ZEUS, and for the internal gas target experiment, HERMES. Routine operation following the upgrade has commenced. Initially experimental backgrounds limited the total beam currents so the number of colliding bunches was reduced while maintaining high single-bunch beam currents. With nominal, pre-upgrade, bunch currents the measured specific luminosity is 2.5 times higher than before, however about 15% smaller than design. Following modifications to alleviate the high backgrounds in 2003, HERA is now again operating with the design number of bunches and the total beam currents are being steadily increased. With only 40% of the total design current, peak luminosities of 2.5 x 1031/cm2s have been demonstrated with a longitudinal polarization of >40%. In this presentation the experiences from the upgrade commissioning will be reviewed. Plans for improvement and pronections for the future will be described.
	Video of talk
	Transparencies
TUXLH03	RHIC Performance and Plans Towards Higher Luminosity and Higher Polarization	gun, focusing, plasma, proton	98
	T. Satogata BNL, Upton, Long Island, New York
	RHIC is the first hadron collider consisting of two independent rings. It is designed to operate over a wide range of beam energies and species, including polarized protons, heavy ions, and asymmetric beam collisions. RHIC has produced physics data at four experiments since 1999 in runs that include gold-on-gold collisions at design beam energy (100 GeV/u), high-energy polarized proton-proton collisions (100 GeV on 100 GeV), and deuteron-gold collisions (100 GeV/u). Recent machine performance will be reviewed for high-luminosity gold-gold operations and polarized proton operations, including causes and solutions for known operational limits. Plans and progress for luminosity and polarization improvements, electron cooling, and the electron-ion collider eRHIC will be discussed.
	Video of talk
	Transparencies
TUYLH01	Proton and Ion Sources for High Intensity Accelerators	gun, focusing, plasma, proton	103
	R. Scrivens CERN, Geneva
	Future high intensity ion accelerators, including SNS, European Spallation Source, SPL etc, will require high current and high duty factor sources for protons, negative hydrogen and heavier ions. In order to achieve these goals, a comparison of the Electron Cyclotron Resonance, radio-frequency and Penning ion sources, among others, will be made. For each of these source types, the present operational sources will be compared to the state-of-the-art research devices with special attention given to reliability and availability. Finally, the future research and development aims will be discussed.
	Video of talk
	Transparencies
TUYLH02	Low and Medium Energy Beam Acceleration in High Intensity Linacs	gun, focusing, plasma, synchrotron	108
	J. Stovall LANL, Los Alamos, New Mexico
	In the past two years accelerator builders have published papers describing mature designs of no fewer than 7 new high-performance proton linacs. These machines are typically designed to deliver multi-megawatt beams for applications in pure and applied research. All of these machines use the radio-frequency quadrupole (RFQ) linac for the first stage of acceleration to reach an energy of a few MeV. In essentially all cases, superconducting elliptical cavities have been adopted as the technology of choice for acceleration above ~100 MeV. Between the RFQ and the high-energy elliptical cavities, designers have proposed no fewer than 6 different types of accelerating structures. In many cases these structures are reaching maturity as a result of active development programs. In this paper, we review the design architectures of the ?low and medium energy? portions of these machines emphasizing recent experience and developments applicable to high-current linac designs.
	Video of talk
	Transparencies
TUYLH03	Challenges facing the Generation of MW Proton Beams using Rapid Cycling Synchrotrons	gun, focusing, plasma, radiation	113
	Y. Irie KEK, Ibaraki
	The MW proton source using rapid cycling synchrotron (RCS) has many challenging aspects, such as (1) large aperture magnets and much higher RF voltages per turn due to a low energy injection and a large and rapid swing of the magnetic field, (2) field tracking between many magnet-families under slightly saturated conditions, (3) RF trapping with fundamental and higher harmonic cavities, (4) H- charge stripping foil, (5) large acceptance injection and extraction straights, (6) beam loss collection, and (7) beam instabilities. These are discussed in details mainly on the basis of the J-PARC 3GeV RCS, which is under construction in Japan. Issues (3) to (7) are common with another scheme of MW spallation neutron source, i.e. full-energy linac + accumulator ring. Comparisons with the SNS design in the US are then made. Reliability/availability of these machines is very important theme which finally determines the successful operations. From the experiences in the existing machines, we will discuss the factors necessary toward the better performance.
	Video of talk
	Transparencies
TUPKF001	Upgrade and Commissioning of the LNLS RF System	gun, focusing, plasma, beamloading	950
	R.H.A. Farias, N.P. Abreu, L.C. Jahnel, L. Liu, C. Pardine, P.F. Tavares LNLS, Campinas
	In this paper we present a report on the commissioning of the new RF system of the electron storage ring of the brazilian synchrotron radiation facility (LNLS).
TUPKF002	TRIUMF ISAC II RF Control System Design and Testing	gun, focusing, plasma, beamloading	953
	M.P. Laverty, S.F. Fang, K. Fong TRIUMF, Vancouver
	The rf control system for the ISAC II superconducting cavities is a hybrid analogue/digital design which has undergone several iterations in the course of its development. In the current design, the cavity operates in a self-excited feedback loop, while phase locked loops are used to achieve frequency and phase stability. Digital signal processors are used to provide amplitude and phase regulation, as well as mechanical cavity tuning control. The most recent version also allows for the rapid implementation of operating firmware and software changes, which can be done remotely, if the need arises. This paper describes the RF control system and the experience gained in operating this system with a four-cavity test facility.
TUPKF003	Industrial Production of the Eight Normal-conducting 200 MHz ACN Cavities for the LHC	gun, focusing, plasma, beamloading	956
	R. Losito, E. Chiaveri, R. Hanni, T.P.R. Linnecar, S. Marque, J. Tuckmantel CERN, Geneva
	The LHC-ACN RF system consists of 8 normal-conducting cavities and is designed to reduce beam losses in the LHC when injecting beams with longitudinal emittance > 0.7 eVs from the CERN SPS. The cavity design took into account the possibility of recuperating all the "ancillary" equipment (tuners, fundamental mode damper, High Order Mode (HOM) couplers) from the old CERN SPS 200MHz system. The cavities are made from OFE copper. The original ingots, procured in Austria, have been forged and pre-formed by pressing them with a 20 tons press, following a procedure defined and adapted for the unusual dimensions of these pieces. The raw components thus obtained were machined and then welded together with an electron beam. In order to get a good repeatability of the fundamental mode frequency across the eight cavities, a procedure has been established with the contractor for the final machining and welding leading to a spread in frequencies below ±20 kHz (< 0.01%). The cavities will be installed in the LHC when losses at high intensities become significant. In the meantime they are undergoing a surface treatment to clean the RF surface and will be stored.
TUPKF004	First Results with a Fast Phase and Amplitude Modulator for High Power RF Application	gun, focusing, plasma, beamloading	959
	D. Valuch, H. Frischholz, J. Tuckmantel CERN, Geneva C. Weil AFT, Backnang
	In a high energy and high power superconducting proton linac, it is more economical to drive several cavities with a single high power transmitter rather than to use one transmitter per cavity. This option has however the disadvantage of not permitting to individually control each cavity, which potentially leads to instabilities. Provided that it can be built at a reasonable cost, a fast phase & amplitude modulator inserted into each cavity feeder line can provide the necessary control capability. A prototype of such a device has been built, based on two fast and compact high power RF phase-shifters, magnetically biased by external coils. The design is described, together with the results obtained at high and low power levels.
TUPKF005	Inductive Output Tube Based 300 kW RF Amplifiers for the Diamond Light Source	gun, focusing, plasma, beamloading	962
	J. Alex, M. Brudsche, M. Frei, M. Müller, A. Spichiger Thales Broadcast & Multimedia AG, Turgi M. Jensen Diamond, Oxfordshire
	All currently operating synchrotron light sources use klystron amplifiers to generate the RF power for the accelerator cavities. In TV broadcasting systems on the other hand, Inductive Output Tubes (IOT)are replacing the classical klystron based systems in all new high power UHF transmitters. The Diamond Light Source will be the first synchrotron to be operated using IOTs. For each accelerating cavity a total of four IOTs will be combined with a waveguide combiner to achieve the RF power requirement of 300 kW at 500 MHz. All IOTs will be supplied from a common crowbarless high voltage power supply. Three such systems will be installed starting in October 2004. This paper gives an overview of the design of the amplifiers, including the first test results from the factory commissioning.
TUPKF006	Custom Design of Medium Energy Linear Accelerator Systems	gun, focusing, plasma, beamloading	965
	K. Dunkel, M. Pekeler, C. Piel, H.P. Vogel, P. vom Stein ACCEL, Bergisch Gladbach
	Based on customer requirements ACCEL Instruments is designing and building medium energy turn-key Linear Accelerator Systems for scientific applications. Within this paper design and performance of third generation synchrotron light source electron injector linacs will be presented. Further the design of a medium energy light ion linear accelerator will be discussed. This light ion accelerator is designed with independently phased superconducting rf cavities for cw operation and acceleration of different particle species and a variable Energy output.
TUPKF007	Series Fabrication Technologies for Normalconducting Linac and Storage Ring Cavities	gun, focusing, plasma, beamloading	968
	P. vom Stein, K. Dunkel, B. Griep, C. Piel, H.P. Vogel ACCEL, Bergisch Gladbach
	Twelve HOM damped 476 MHz single cell cavities have been delivered for PEP II and the production of several 805 MHz CCL modules for SNS has recently been finalised by ACCEL Instruments. Based on those two examples, required key technologies for cavity production will be introduced. Final prove of successful manufacturing is given by low level rf measurements. Results of those measurements for above mentioned projects will be presented within this paper.
TUPKF008	Status of the HoBiCaT Superconducting Cavity Test Facility at BESSY	gun, focusing, plasma, beamloading	970
	J. Knobloch, W. Anders, J. Borninkhof, S. Jung, M. Martin, A. Neumann, D. Pflückhahn, M. Schuster BESSY GmbH, Berlin
	BESSY has recently constructed the HoBiCaT cryogenic test facility for superconducting TESLA cavity units, including all ancillary devices (helium tank, input coupler, tuner, magnetic shielding). It is designed to house two such units in a configuration similar to that envisaged for the superconducting CW linac of the BESSY FEL. These units are presently being fabricated, prepared and assembled by industry. HoBiCaT will be used to address many of the issues that must be considered prior to finalizing the design of the proposed linac. Rapid turn-around-tests permit the investigation of items such as RF regulation, microphonic detuning and cryogenic parameters/achievable pressure stability. These test will also serve as the first step towards qualifying the industrial production of assembled cavity units. The commissioning of HoBiCaT is scheduled for Spring 2004 and the current status is presented here.
TUPKF009	RF Control of the Superconducting Linac for the BESSY FEL	gun, focusing, plasma, beamloading	973
	J. Knobloch, A. Neumann BESSY GmbH, Berlin
	In the BESSY-FEL superconducting linac, precise RF control of the cavities' voltage is imperative to maintain a bunch-to-bunch time jitter of less than 50 fs for synchronization in the HGHG section. The average beam loading is less than 1.5 kW/m and the cavity bandwidth is small so that high-gain RF feedback is required. Noise, in particular microphonic detuning, strongly impact the achievable level of control. Presented here are simulations of the cavity-feedback system, taking into account beam loading and noise sources such as measurement noise, microphonics and injection jitter. These simulations are used to estimate the resultant time and energy jitter of the bunches as they enter the HGHG section of the BESSY FEL.
TUPKF010	Cryogenic Considerations for CW Operation of TESLA-type Superconducting Cavity Modules for the BESSY FEL	gun, focusing, plasma, beamloading	976
	J. Knobloch, W. Anders, X. Yu BESSY GmbH, Berlin
	The proposed BESSY FEL uses a CW superconducting driver linac to provide acceleration up to 2.3 GeV. Its design is based on well-established TESLA technology, originally intended for heat loads of order 1 W/m at 2.0 K. CW operation increases this load to levels of order 15 W/m at 1.8 K for a total heat load of 3 kW at 2.3 GeV (given conservative assumptions for the attainable Q-factor). Presented here is an analysis of the cryogenic layout, including two-phase-flow simulations of the 1.8-K helium which help identify the changes needed for reliable CW operation. A modified ‘‘CW'' module and helium distribution scheme is proposed.
TUPKF011	First Tests of a HOM-Damped High Power 500MHz Cavity	gun, focusing, plasma, beamloading	979
	F. Marhauser, E. Weihreter BESSY GmbH, Berlin
	A prototype high power 500 MHz copper cavity with three tapered circular waveguides for broadband higher order mode (HOM) damping has been fabricated especially for the use in 3rd generation synchrotron radiation sources. Low power impedance measurements are presented and compared with theoretical simulations to verify the expected HOM damping efficiency as well as the fundamental mode shunt impedance. After a careful cleaning and baking process to reduce the vacuum pressure the cavity has been conditioned at high power. All relevant parameters of the cavity are reported.
TUPKF012	A HOM Damped Planar Accelerating Structure	gun, damping, focusing, plasma	982
	A. Blednykh, H. Henke TET, Berlin
	The problem of very fast higher order mode (HOM) suppression, in the order of 1ns, was investigated for a planar 30GHz accelerating structure. Both, damping and detuning were considered. A sufficient suppression could be achieved by damping waveguides in every cell in vertical and in horizontal direction. Finally, a scaled-up 10GHz model was built. It is a 35 cm long aluminum structure, which was machined by high-precision milling. In order to reduce the surface gradient on the input/output coupling irises a symmetrical RF coupler was developed. The HOM damping is accomplished by coupling six damping waveguides to each accelerating cell. The waveguides are loaded by a low resitivity RF load. The whole structure with waveguides and loads was optimized by means of the computer code GdfidL. The paper gives the design criteria and the results of s-parameter and bead-pull measurements.
TUPKF013	Studies on Maximum RF Voltages in Ferrite-tuned Accelerating Cavities	gun, damping, focusing, plasma	985
	K. Kaspar, H.G. Koenig, T. Winnefeld GSI, Darmstadt
	The GSI SIS100 project requires very high accelerating voltages. With ferrite-tuned synchrotron cavities the gap voltage is often strongly limited by the Q-loss effect appearing at medium dc bias fields. At low bias fields, considerably higher voltages can be reached, however. The maximum usable amplitudes over the bias region have been studied. At zero bias, the ferrites could be driven to more than a factor 3 above the Q-loss limit. Except overheating, no other problems appeared. With increasing bias, the maximum amplitudes decrease continuously to the Q-loss level. In this fall-off region there is still a tuning factor up to 2.5 available, with rf flux densities by at least a factor 2 above the Q-loss level. Measurements on small samples of the ferrite material used in the GSI cavities could be verified very well in a full-size cavity, for the most part. The tests were mainly limited by the available anode voltage and the fear of damaging the cavity. It seems possible, to generalize the main results for other ferrite materials, also. Based on the results, a possible scenario for the SIS100 rf system is given. Additionally, the results lead to an alternative cavity design for higher voltages, which is described as well.
TUPKF014	Electromagnetic Design of New RF Power Couplers for the S-DALINAC	gun, damping, focusing, plasma	988
	M. Kunze, W.F.O. Müller, T. Weiland TEMF, Darmstadt M.B. Brunken, H.-D. Gräf, A. Richter TU Darmstadt, Darmstadt
	New rf power couplers for the Superconducting Darmstadt Linear Accelerator (S-DALINAC) injector have to be designed to transfer rf power up to 2 kW to the electron beam. This allows injector operation at beam currents from 0.15 mA to 0.2 mA and electron energies up to 14 MeV. The new couplers should possibly provide a variable external Q in the range from 5·106 to 3·109 and a small transverse kick. A variable coupling is needed to allow for perfect matching in the case of beam loading and when no beam is present, respectively. The second operation stage is used for cavity diagnostics. The asymmetric field distribution of the couplers generates emittance growth of the electron beam and therefore the transverse kick has to be minimized. Electromagnetic simulations are applied to investigate different coupler designs and to localize possible problems at an early stage. Cavity external Q and transverse kick can be calculated from 3D electromagnetic eigenmode solutions. The present coaxial-coaxial input couplers at the S-DALINAC are limited to power operation below 500 W under full reflection. Therefore, to reach power operation up to 2 kW two possible new realizations of low-kick waveguide couplers for the S-DALINAC injector are presented, namely a single-waveguide and a twin-waveguide coupler.
TUPKF015	Status of the Superconducting CH-Structure	gun, damping, focusing, plasma	991
	H. Podlech, H. Deitinghoff, H. Klein, H. Liebermann, U. Ratzinger, A.C. Sauer, R. Tiede IAP, Frankfurt-am-Main
	H-mode cavities (IH-DTL, IH-RFQ, 4-Vane-RFQ) have been developed and operated successfully during the last decades for ion acceleration. At the IAP Frankfurt a new type of H-mode cavity, the CH-structure is under development. This multi cell drift tube cavity is operated in the TE21- mode. Due to its mechanical rigidity, room temperature as well as superconducting versions can be realized. Superconducting CH-structures might be used especially for cw operated linacs in nuclear research facilites and applied research projects like XADS or IFMIF. A superconducting 352 MHz CH-structure (beta=0.1) with 19 gaps will be available for first tests in 2004. We present the status of the cavity and of the new cryo laboratory in Frankfurt.
TUPKF016	Dynamic Lorentz Force Detuning Studies in TESLA Cavities	gun, damping, focusing, plasma	994
	V. Ayvazyan, S. Simrock DESY, Hamburg
	Dynamic detuning of the superconducting rf cavities due to Lorentz force induced mechanical excitation is a critical concern since the magnitude can approach the cavity bandwidth and require significant additional rf power for field control. In this paper, the influence of high accelerating fields on the resonance frequency in superconducting TESLA cavities is discussed. Cavities at the TESLA Test Facility have been operated at the design operating gradient close to 25 MV/m. It is shown that Lorentz force detuning constant factors are different for different cavities, significant spread have been observed.
TUPKF017	Electrons Beam Dynamics of the 100 MeV Preinjector Helios for the SOLEIL Synchrotron	damping, focusing, plasma, linac	997
	A.S. Setty THALES, Colombes
	A 100 MeV electron linac is under construction, in order to inject into the booster synchrotron of SOLEIL. The linac is designed to work according to two operation modes : a short pulse mode (2 ns - 0,5 nC) and a long pulse mode (300 ns - 8 nC). Calculation of the beam dynamics, using our selfmade code PRODYN, has been carried out from the gun to the end of the linac. Special care has been taken on the gun design to avoid an overfocusing outcoming beam in order to obtain a final low emittance. Calculations results are given.
TUPKF018	Surface Morphology at the Quench Site	damping, focusing, plasma, linac	1000
	S. Berry, C.Z. Antoine, M. Desmons CEA/DSM/DAPNIA, Gif-sur-Yvette
	It has been demonstrated recently that local magnetic field enhancement can originate from roughness (e.g. steps at grain boundaries). We are willing to investigate if the quench observed in superconducting niobium cavities can be related to such morphological defects. We recently developed two kinds of tool. 1) A replica technique that allows to reproduce the internal surface of cavities (non destructive testing). 2) A morphological analysis tool. Classical roughness measurements are not adapted to determine local curvature radius.This paper describes a new topological approach aiming at a better characterization of the surface morphology. We also present results of this technique applied to replica taken from cavities at the quench site.
TUPKF019	Recent Developments on Superconducting b035 and b015 Spoke Cavities at IPN for Low and Medium Energy Sections of Proton Linear Accelerators.	damping, focusing, plasma, linac	1003
	G. Olry, J.-L. Biarrotte, S. Blivet, S. Bousson, F. Chatelet, D. Gardès, N. Hammoudi, T. Junquera, J. Lesrel, C. Miélot, A.C. Müller, D. Ruffier, H. Saugnac, P. Szott, J.P. Thermeau IPN, Orsay
	Spoke cavities studies leaded by IPN-Orsay, for both XADS and EURISOL projects, are fully integrated within the 5th and 6th European Framework Programs. During 2003, several tests have been performed on the first b035 spoke cavity prototype. They have demonstrated the great potential of this type of cavity in term of RF performances (Eacc max=12.5 MV/m at T=4.2 K) and mechanical behavior (very low sensitivity to errors fabrication, good stiffness…). Following the upgrade of our cryogenic facility, we have tested, this spring, the cavity at 2 K. These new results will be presented in this paper. In parallel, the fabrication of a new spoke cavity (2-gap, 352 MHz, b015) has begun in January. While keeping the same geometry than that of the b035 cavity, we carried out significant changes on the coupler port and stiffening system designs. We report here in particular, RF calculations concerning the new location of the coupler port (in order to minimize losses due to magnetic field) and also, mechanical calculations about the new stiffening ring. Finally, we will present the preliminary thought on modular cryomodule which are based on the ?short? cryomodule concept used with the Quarter Wave Resonators for the SPIRAL-2 project.
TUPKF020	Numerical Investigation on the ELETTRA 500 MHz Power Coupler	damping, focusing, plasma, linac	1006
	C. Pasotti, P. Craievich, A. Fabris, G. Penco, M. Svandrlik ELETTRA, Basovizza, Trieste B. B. Baricevic DEEI, Trieste
	Due to the high input power required to feed a resonant cavity, the RF input coupler is a critical component for the reliability of an RF system. The 500 MHz RF input coupler for the ELETTRA cavities was specified for 150 kW input power. It is important to investigate the performance limits of the coupler in view of increasing RF power requirements. The coupler's maximum peak field and dissipation versus the input power have been studied by means of the numerical simulator HFSS. Possible improvements to the existing design have been investigated. The optimization has to take into consideration the following requirements: convenient power transmission efficiency, RF matching, suitable coupling coefficient, negligible perturbation on cavity voltage, moderate operating temperature and stress.
TUPKF021	First Year of Operation of SUPER-3HC at ELETTRA	focusing, plasma, linac, beamloading	1009
	G. Penco, P. Craievich, A. Fabris, C. Pasotti, M. Svandrlik ELETTRA, Basovizza, Trieste
	Since July 2003 a superconducting third harmonic cavity has been in routine operation at ELETTRA. When the cavity is activated the stored electron bunches are lengthened by about a factor of three. The related longitudinal Landau damping has allowed first time operation at 320 mA, 2.0 GeV with a beam completely free of longitudinal coupled bunch instabilities. With the cavity active the lifetime at 320 mA, 2.0 GeV is three times the theoretical value for nominal bunch length. The increase in beam stability and lifetime contributed significantly to enhance the brightness and the integrated flux of the source. We will further discuss the operating experience with the superconducting cavity and the cryogenic system, analyzing the impact of the new system on machine operation and uptime. Finally we will also report on the characterization of the cavity performance for different filling patterns of the storage ring and relate the results to preliminary beam-cavity interaction studies.
TUPKF022	Constructionand Testing of the Beta=0.31, 352 MHz Superconducting Half-wave Resonator for the SPES Project	focusing, plasma, linac, beamloading	1012
	A. Facco, W. Lu, F. Scarpa INFN/LNL, Legnaro, Padova E. Chiaveri, R. Losito CERN, Geneva V. Zviagintsev TRIUMF, Vancouver
	The interest in low- and medium- beta superconducting cavities is presently focused to future high intensity proton, deuteron and heavy ion linacs. A particular application is acceleration of cw and pulsed beams of variable q/A, which requires cavities with a small number of gaps and excellent mechanical stability. We have designed and constructed a 2 gap, 352 MHz SC half wave cavity aiming to similar characteristics and fitting the requirements of the intermediate-beta section of the LNL-SPES driver. The status of the project and the first test results will be presented.
TUPKF023	Construction of a 161 MHz, beta=0.16 Superconducting QWR with Steering Correction for RIA	focusing, plasma, linac, beamloading	1015
	A. Facco, W. Lu, F. Scarpa INFN/LNL, Legnaro, Padova E. Chiaveri, R. Losito CERN, Geneva T.L. Grimm, W. Hartung, F. Marti, R.C. York NSCL, East Lansing, Michigan V. Zviagintsev TRIUMF, Vancouver
	We have built a 161 MHz, b=0.16 superconducting Quarter Wave Resonator with steering correction for the low beta section of RIA. This bulk niobium, double wall cavity, compatible with both separate vacuum between beam line and cryostats or unified one, was designed in collaboration between MSU-NSCL and LNL. The design is suitable for extension to other frequencies, e.g. to obtain the 80 MHz, beta=0.085 cavity required in RIA. The shaped drift tube allows correction of the residual QWR steering that can cause emittance growth especially in light ions; this could make this resonator a good alternative to Half-Wave resonators in high intensity proton-deuteron linacs, like the SPES injector project at LNL. First test results will be presented.
TUPKF024	Operation Experience with ALPI Nb/Cu Resonators	focusing, plasma, linac, beamloading	1018
	A.M. Porcellato, L. Bertazzo, M. De Lazzari, D. Giora, V. Palmieri, S. Stark, F. Stivanello INFN/LNL, Legnaro, Padova
	The refurbishing, by replacing the Pb superconducting film by Nb, of ALPI QW accelerating resonators was completed in 2003. All the 52 cavities are now in operation showing a large increase in the average accelerating field, which exceeds 4.5 MV/m (21 MV/m pick electrical surface field). The performance of renewed resonators has been increasing with time reaching 6MV/m in the last produced units. The increase in ALPI performance and the advantage in conditioning and setting time obtained by the upgrading process will be reported.
TUPKF025	Superconducting Niobium Film for RF Applications	focusing, plasma, linac, beamloading	1021
	A. Cianchi, L. Catani, A. Cianchi, S. Tazzari INFN-Roma II, Roma Y.H. Akhmadeev Institute of High Current Electronics, Tomsk A. Andreone, G. Cifariello, E. Di Gennaro, G. Lamura Naples University Federico II, Napoli J.L. Langner The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock R.R. Russo Università di Roma II Tor Vergata, Roma
	Thin niobium film coated copper RF cavities are an interesting possible alternative to bulk-Nb cavities since copper is much cheaper than niobium, it has higher thermal conductivity and a better mechanical stability. Unfortunately, the observed degradation of the quality factor with increased cavity voltage of sputtered accelerating cavities restricts their usage in future large linear accelerators needing gradients higher than 15MV/m. We are developing an alternate deposition technology, based on a cathodic arc system working in UHV conditions. Its main advantages compared to standard sputtering are the ionized state of the evaporated material, the absence of gases to sustain the discharge, the much higher energy of atoms reaching the substrate surface and the possibility of higher deposition rates. To ignite the arc we use a Nd-YAG pulsed laser focused on the cathode surface that provides a reliable and ultraclean trigger. Recent results on the characterization of niobium film samples produced under different conditions are presented showing that the technique can produce bulk-like films suitable for RF superconducting applications.
TUPKF026	RF Tests of the Beta=0.5 Five Cell TRASCO Cavities	focusing, plasma, linac, beamloading	1024
	A. Bosotti, C. Pagani, P. Pierini INFN/LASA, Segrate (MI) J.P. Charrier, B. Visentin CEA/DSM/DAPNIA, Gif-sur-Yvette G. Ciovati, P. Kneisel Jefferson Lab, Newport News, Virginia
	Two complete 5 cell superconducting cavities at b=0.5 have been designed and fabricated. The cavities have been designed to minimize peak electric and magnetic fields, with a goal of 8.5 MV/m of accelerating gradient, at a Q > 5E9. The cavities are currently in the testing stage and the results of the vertical tests will be presented at this conference.
TUPKF031	Non-resonant Accelerating System at the KEK-PS Booster	focusing, plasma, linac, booster	1027
	S. Ninomiya, M. Muto, M. Toda KEK, Ibaraki
	The non-resonant accelerating system for the KEK-PS booster accelerator has been constructed. The system has been operating since October 2003 without trouble. The accelerating gap in the system is loaded with magnetic cores of high permeability. The cores produce high resistive impedance at the gap. The power dissipated in the cores amounts to 50kW at 16kV accelerating voltage. It is removed by forced-air cooling system. At the last operation of the accelerator, with the help of new COD-correction system, the average beam intensity of the booster increased to 2.6E+12ppp, which is 30% higher than before.
TUPKF032	COD Correction by Novel Back-leg at the KEK-PS Booster	focusing, plasma, linac, booster	1030
	S. Ninomiya, K. Satoh, H. Someya, M. Toda KEK, Ibaraki
	The COD correction is performed by using new driving system of back-leg windings. Two back-leg coils of the separate magnets are connected to make a closed circuit in which the induced voltages of the two magnets have opposite phases to each other. When the current source is inserted into the closed loop, the current drives the two magnets with opposite polarities. If the pair of magnets is properly selected, the current effectively corrects the orbit distortion. The selection rule of the pair is as follows; one is the magnet at the maximum distortion and the second magnet is that separated with the betatron phase of -90deg. The correction system at the KEK-PS Booster reduced the COD to less than 1/5 of that without correction, and increased the capture efficiency. The average beam intensity of our Booster is increased from 2E+12 to 2.6E+12ppp.
TUPKF033	Cryogenic Performance of the Prototype Cryomodule for ADS Superconducting LINAC	focusing, plasma, booster, beamloading	1033
	N. Ohuchi, E. Kako, S. Noguchi, T. Shishido, K. Tsuchiya KEK, Ibaraki N. Akaoka, H. Kobayashi, N. Ouchi, T. Ueno JAERI/LINAC, Ibaraki-ken T. Fukano Nippon Sanso Corporation, Tokyo H. Hara, M. Matsuoka, K. Sennyu MHI, Kobe
	A prottype cryomodule containing two 9-cell superconducting cavities of b=0.725 and f=972MHz is being constructed under the collaboration of Japan Atomic Energy Research Institute (JAERI) and High Energy Accelerator Research Organization (KEK) on the development of superconducting LINAC for Accelerator Driven System (ADS). Cryogenic performances of the cryomodule and 2K He-system will be reported.
TUPKF034	Low Output-Impedance RF System for 2nd Harmonic Cavity in the ISIS Synchrotron	focusing, plasma, impedance, booster	1036
	T. Oki, S. Fukumoto, Y. Irie, M. Muto, S. Takano, I. Yamane KEK, Ibaraki R.G. Bendall, I.S.K. Gardner, M.G. Glover, J. Hirst, D. Jenkins, A. Morris, S. Stoneham, J.W.G. Thomason, T. Western CCLRC/RAL/ISIS, Chilton, Didcot, Oxon J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf, G. Pile ANL, Argonne, Illinois
	In the ISIS facility based at Rutherford Appleton Laboratory (RAL) in the UK, second target station project was funded, which requires to increase the current intensity by 1.5-times (300 micro-A). Four 2nd harmonic RF cavities will be installed in the ISIS synchrotron in order to increase the trapping efficiency, and to mitigate the space charge detuning. A very low output-impedance RF system for the 2nd harmonic cavity has been developed by the collaboration between RAL, Argonne National Laboratory (US) and KEK (Japan). The system comprises the 240 kW triode as a final amplifier with plate-to-grid feedback path. The measured output-impedance was less than 30 ohms over the frequency range of 2.7 - 6.2 MHz, which agreed well with calculations. High power test was also performed under frequency swept mode at 50 Hz repetition. The operation was almost stable, and more than 12 kVpp was obtained as maximum. The voltage gain of the final amplifier was 25 - 30, which decreased gradually with frequency due to decreasing input-impedance of triode. The beam test is planned at ISIS in near future.
TUPKF035	RF System for Compact Medical Proton Synchrotron	focusing, plasma, impedance, acceleration	1039
	Z. Fang, K. Egawa, K. Endo, S. Yamanaka KEK, Ibaraki Y. Cho, T. Fusato, T. Hirashima DKK, Kanagawa
	The rf system has been developed for the compact medical proton synchrotron. The rf system will be operated in pulse mode with the fundamental rf frequency sweeping from 1.6 to 15 MHz during the acceleration time of 5 ms. The required rf cavity voltage is a function of acceleration time too, with the voltage of fundamental varying from 13 to 6 kV. Besides, high order harmonics are also considered to apply to the rf system, and the cavity peak voltage varying from 20 to 9 kV during the acceleration time is expected. The performance of the rf system is being studied and will be presented.
TUPKF036	RF Property of the Prototype Cryomodule for ADS Superconducting Linac	focusing, plasma, impedance, acceleration	1042
	E. Kako, S. Noguchi, N. Ohuchi, T. Shishido KEK, Ibaraki N. Akaoka, H. Kobayashi, N. Ouchi, T. Ueno JAERI/LINAC, Ibaraki-ken H. Hara, M. Matsuoka, K. Sennyu MHI, Kobe
	A prototype cryomodule containing two 9-cell superconducting cavities of beta=0.725 and frequency=972MHz is being constructed under the collaboration of Japan Atomic Energy Research Institute (JAERI) and High Energy Accelerator Research Organization (KEK) on the development of superconducting LINAC for Accelerator Driven System (ADS). Design and performance of RF components will be reported.
TUPKF037	Multi-harmonic RF Acceleration System for a Medical Proton Synchrotron	focusing, plasma, impedance, booster	1045
	K. Saito, M. Katane, K. Kobayashi, K. Masui, K. Moriyama, H. Nishiuchi, H. Sakurabata, H. Satomi Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken
	We have developed an RF accelerating system for medical proton synchrotron. The RF cavity is a tuning-free wideband type, loaded with FINEMET cores, which is driven by a solid-state RF power amplifier with operation frequency range between 1MHz and 10MHz. Multi-harmonic RF acceleration scheme has been realized with the RF control system, to reduce beam loss by space-charge effect in low energy region. The original techniques for high-speed digital signal processing and high-precision RF signal processing have been applied, in order to fulfill feedback control of the frequency, phase and amplitude of the second and third harmonic RF signals as well as the fundamental one.
TUPKF038	Reduced Length Designs of 500 MHz Damped Cavity Using SiC Microwave Absorber	focusing, plasma, impedance, booster	1048
	T. Koseki RIKEN/RARF/BPEL, Saitama M. Izawa, S. Sakanaka, T. Takahashi, K. Umemori KEK, Ibaraki
	We present a new 500 MHz HOM (Higher-Order Modes) damped cavity for high brilliance synchrotron radiation sources. The design is based on the damped cavity, which is operated at the Photon Factory storage ring in KEK. The PF cavity has a large hole beam duct (140 mm in diameter), a part of which is made of a silicon carbide (SiC) microwave absorber. The new cavity, proposed in this paper, has parallel-plate radial transmission lines on the beam duct instead of the SiC beam duct. The outer end of the radial line is terminated by SiC absorbers. The HOMs, extracted from the center part of the cavity through the beam duct, propagate in the radial line and are dissipated in the absorber. The accelerating mode is not affected by the radial line damper since the frequency is sufficiently below the cutoff of the 140-mm beam duct. In this paper, optimized design of the radial line damper and damping properties for HOMs are described in detail.
TUPKF039	The Experiences of Operation and Performance about the 500 MHz CW Klystrons at the PLS Storage Ring	focusing, plasma, impedance, booster	1051
	J.S. Yang, M.-H. Chun, Y.J. Han, S.-H. Nam, I.H. Yu PAL, Pohang
	There are four RF stations to supply the energy to electron at the storage ring of the Pohang Light Source(PLS). From the beginning of the operation of RF system, 500MHz 60kW(CW) klystrons have been operated. As the operation time of the tubes are increased, their performances are decreased. Therefore three 60kW tubes were replaced with the same model and two 75kW klystrons were replaced with 60 kW klystrons so far. Nowadays two 75 kW and two 60 kW klystrons are operated in the RF system of PLS. Our experiences of the klystron operation and their general performance are described in this paper.
TUPKF041	Quasi-optic RF Power Transmission Line from a FEM Oscillator to the Model of the CLIC Accelerating Structure	focusing, plasma, impedance, booster	1054
	A. Kaminsky, A.V. Elzhov, E.A. Perelstein, N.V. Pilyar, T.V. Rukoyatkina, S. Sedykh, A.P. Sergeev, A. Sidorov JINR, Dubna, Moscow Region N.S. Ginzburg, S.V. Kuzikov, N.Yu. Peskov, M.I. Petelin, A. Sergeev, N.I. Zaitsev IAP/RAS, Nizhny Novgorod
	Experimental investigation of a copper resonator lifetime under multiple action of 30 GHz power pulses is now carried out by the collaboration of CLIC team (CERN), FEM group of JINR (Dubna) and IAP RAS (Nizhny Novgorod). A quasi-optic two-mirror transmission line is used between the FEM oscillator and test cavity. An oversized FEM output waveguide based on the wavebeam transformation (Talbot effect) provides the optimal transverse distribution of the radiation, eliminates the output window breakdown and decrease the influence of the reflected wave on the FEM oscillator regime.
TUPKF048	Studies of Electron Multipacting in CESR Type Rectangular Waveguide Couplers	focusing, plasma, impedance, booster	1057
	P. Goudket, M. Dykes CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire S.A. Belomestnykh, R. Geng Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York R.G. Carter Microwave Research Group, Lancaster University, Lancaster H. Padamsee Cornell University, Ithaca, New York
	The latest results from an experimental waveguide section, as well as simulations from a model of electron multipacting using the MAGIC PIC code, are discussed. Tests were carried out on a new waveguide section that included enhanced diagnostics and the possibility of changing surface materials and temperature. Those tests evaluated grooves, ridges and surface coatings, such as TiN and a TiZrV NEG coating, as methods of multipactor suppression. The conclusion remains that the most effective method to achieve complete multipactor suppression remains the application of a static magnetic bias of approximately 10G. The experiments also provided good data sets that can be used to verify the accuracy of simulations. Simulations of the waveguide multipacting have been carried out and have offered better understanding of electronic behaviour.
TUPKF049	Combining Cavity for RF Power Sources: Computer Simulation and Low Power Model	focusing, plasma, impedance, booster	1060
	E. Wooldridge, S.C. Appleton, B. Todd CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	A combining cavity for RF power sources has been investigated as a way of saving space, in comparison to waveguides, and as a way of combining power with graceful degradation if one or more component were to fail. The cavity has been investigated as the maximum power output of an Inductive Output Tube (IOT) for CW is 80KW at 500MHz and a proposed output of 20KW at 1.3GHz and most RF systems for particle accelerators require much more than this. Although 1.3GHz klystrons do exist they are vastly more expensive to purchase and maintain. Also the down time could be minimised to minutes in the even of a single IOT failure where as a klystron has a minimum downtime of several days in the event of a failure. Initially the cavity and its inputs were simulated in CSTs? Microwave studio. After optimising the cavity to ensure the minimum reflection at the input ports and maximum transmission at the output port, a low power model was then created from aluminium. Signal generators were used to power the model and a network analyser was used to check the output. The model was used to compare the results gained from the computer simulation and to obtain results from asymmetric positioning of the ports, which was not possible in the simulation.
TUPKF050	Triggers for RF Breakdown	focusing, plasma, impedance, booster	1063
	J. Norem, Z. Insepov ANL, Argonne, Illinois
	We outline a model of breakdown in rf cavities. Breakdown can be triggered by two mechanisms, one is fracture of the surface due to the tensile stress produced by the electric field, the second is Ohmic heating at grain boundaries and defects at very high current densities. We show how this model follows from measurements of local electric fields using electron field emission, and show how the model applies to the operating conditions of a variety of rf structures. This model may have some relevance to SCRF and DC structures.
TUPKF051	A 500 kV Power System for a Gridded Sheet-beam Klystron	klystron, focusing, plasma, cathode	1066
	M.A. Kempkes, F.O. Arntz, J.A. Casey, M.P.J. Gaudreau, N. Reinhardt, R.P. Torti Diversified Technologies, Inc., Bedford
	The Next Generation Linear Collider (NLC) will require hundreds of X-band high power klystrons. These klystrons are typically cathode pulsed at 500 kV and 265 A each, with 1.6 microsecond pulses of RF, and a complex microwave delay line to achieve 400 ns RF pulses. Because the pulsed voltage is so high, CV2f losses will lead to many millions of dollars per year of wasted power. The klystron group at SLAC, working with Calabazas Creek Research (CCR), is developing a gridded, sheet beam klystron. This new klystron design avoids the CV2 losses of cathode pulsing because its cathode is not pulsed - it remains at a constant high voltage. Instead, the grid voltage is pulsed over a much smaller (6 kV) voltage range. This paper will describe DTI's progress in development of the electronics required to drive this new klystron, including a 500 kV multiplier power supply and grid modulator, a multi-concentric high voltage cable, which also acts as the pulse forming line, and an advanced, reentrant cable connection to the klystron itself. This design allows the klystron to be located adjacent to the beamline, and separated from the power electronics, improving RF efficiency, maintainability, and overall reliability.
TUPKF053	New Waveguide-type HOM Damper for the ALS Storage Ring RF Cavities	focusing, plasma, cathode, impedance	1069
	S. Kwiatkowski, K.M. Baptiste, J. Julian LBNL/ALS, Berkeley, California
	The ALS storage ring 500 MHz RF system uses two re-entrant accelerating cavities powered by a single 320kW PHILLIPS YK1305 klystron. During several years of initial operation, the RF cavities were not equipped with effective passive HOM damper systems. Longitudinal beam stability was achieved through cavity temperature control and the longitudinal feedback system (LFB), which was often operating at the edge of its capabilities. As a result, longitudinal beam stability was a significant operations issue at the ALS. During two consecutive shutdown periods (April 2002 and 2003) we installed E-type HOM dampers on the main and third harmonic cavities. These devices dramatically decreased the Q-values of the longitudinal anti-symmetric HOM modes. The next step is to damp the rest of the longitudinal HOM modes in the main cavities below the synchrotron radiation damping level. This will hopefully eliminate the need for the LFB and set the stage for a possible increase in beam current. The ?waveguide? type of HOM damper was the only option that didn?t significantly compromise the vacuum performance of the RF cavity. The design process and the results of the low level measurements of the new waveguide dampers are presented in this paper.
TUPKF055	Space-charge-limited Magnetron Injection Guns for Gyroklystrons	focusing, plasma, impedance, booster	1072
	W. Lawson Maryland University, College Park, Maryland
	We present the results of several space-charge-limited (SCL) magnetron injection gun (MIG) designs which are intended for use with a 500 kV, 500 A gyroklystron with accelerator applications. The design performances are compared to that of a temperature-limited (TL) gun that was constructed for the same application. The SCL designs yield similar values for beam quality, namely an axial velocity spread under 3% for an average perpendicular-to-parallel velocity ratio of 1.5. The peak electric fields and the cathode loadings of the SCL designs are somewhat higher than for the TL design. Three designs are described in this paper. In the first design the space-charge limit is achieved by recessing the emitter into the cathode. The other two designs have control electrodes to which a voltage can be applied to change the beam current independently of the beam voltage. One of these designs can accept a bias sufficiently high to cut off the current completely, so that a DC power supply with pulsed grid operation is possible. Details of all designs as well as a discussion of the advantages and disadvantages of the SCL designs as compared to the TL design will be given.
TUPKF056	Multipacting in Crossed RF Fields near Cavity Equator	focusing, plasma, impedance, booster	1075
	V.D. Shemelin Cornell University, Ithaca, New York
	Electric and magnetic fields near the cavity equator are presented in a form of expansions up to the third power of coordinates. Comparisons with numerical calculations made with the SLANS code for the TESLA and other cavity cells, as well as with the analytical solution for a spherical cavity are done. These fields are used for solution of equations of motion. It appears that for description of motion, the only main terms of the expansion are essential, but the value of coefficients for the electric field components depend on details of magnetic field behavior on the boundary. Equations of motion are solved for electrons moving in crossed RF fields near the cavity equator. Based on the analysis of these equations, general features of this kind of multipacting are obtained. Results are compared with simulations and experimental data. The "experimental" formulas for multipacting zones are explained and their dependence on the cavity geometries is shown. Developed approach allows evaluation of multipacting in a cavity without simulations but after an analysis of fields in the equatorial region. The fields can be computed by any code used for cavity calculation.
TUPKF058	Test Results for the New 201.25 MHz Tetrode Power Amplifier at LANSCE	focusing, plasma, impedance, booster	1078
	J.T.M. Lyles, S. Archuletta, J. Davis, L. Lopez, G. Roybal LANL/LANSCE, Los Alamos, New Mexico
	A new RF amplifier has been constructed for use as the intermediate power amplifier stage for the 201.25 MHz Alvarez DTL at LANSCE. It is part of a larger upgrade to replace the entire RF plant with a new generation of components. The new RF power system under development will enable increased peak power with higher duty factor. The first tank requires up to 400 kW of RF power. This can be satisfied using the TH781 tetrode in a THALES cavity amplifier. The same stage will be also used to drive a TH628 Diacrode? final power amplifier for each of the three remaining DTL tanks. In this application, it will only be required to deliver approximately 150 kW of peak power. Details of the system design, layout for DTL 1, and test results will be presented.
TUPKF059	Simulation of Dark Currents in X-band Accelerator Structures	focusing, plasma, impedance, booster	1081
	K.L.F. Bane, V.A. Dolgashev, G.V. Stupakov SLAC, Menlo Park, California
	In high gradient accelerator structures, such as those used in the main linac of the GLC/NLC, electrons are emitted spontaneously from the structure walls and then move under the influence of the rf fields. In this report we study the behavior of this "dark current" in X-band accelerator structures using a simple particle tracking program and also the particle-in-cell program MAGIC. We address questions such as what is the sensitivity to emission parameters, what fraction of dark current is trapped and reaches to the end of a structure, and what are the temporal, spatial, and spectral distributions of dark current as functions of accelerating gradient.
TUPKF061	The SPEAR3 RF System	focusing, plasma, impedance, booster	1084
	P.A. McIntosh, S. Allison, P. Bellomo, S. Hill, V. Pacak, S. Park, J.J. Sebek, D.W. Sprehn SLAC, Menlo Park, California
	SPEAR2 was upgraded in 2003, to a new 3rd Generation Light Source (3GLS) enabling users to take better advantage of almost 100x higher brightness and flux density over its predecessor SPEAR2. As part of the upgrade, the SPEAR2 RF system has been re-vamped from its original configuration of one 200 kW klystron feeding a single 358.5 MHz, 5-cell aluminum cavity; to a 1.2 MW klystron feeding four 476.3 MHz, HOM damped copper cavities. The system installation was completed in late November 2003 and the required accelerating voltage of 3.2 MV (800 kV/cavity) was very rapidly achieved soon after. This paper details the SPEAR3 RF system configuration and its new operating requirements, highlighting its installation and subsequent successful operation.
TUPKF062	PEP-II RF System Operation and Performance	focusing, plasma, impedance, booster	1087
	P.A. McIntosh, J. Browne, J.E. Dusatko, J.D. Fox, W.C. Ross, D. Teytelman, D. Van Winkle SLAC, Menlo Park, California
	The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2002. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured.
TUPKF063	Current Status of the Next Linear Collider X-band Klystron Development Program	klystron, plasma, impedance, booster	1090
	D.W. Sprehn, G. Caryotakis, A.A. Haase, E.N. Jongewaard, C. Pearson SLAC, Menlo Park, California
	Klystrons capable of driving accelerator sections in the Next Linear Collider have been developed at SLAC during the last decade. In addition to fourteen 50 MW solenoid-focused devices and a 50 MW Periodic Permanent Magnet focused (PPM) klystron, a 500 kV 75 MW PPM klystron was tested in 1999 to 80 MW with 3-microsecond pulses, but very low duty. Subsequent 75 MW prototypes aimed for low-cost manufacture by employing reusable focusing structures external to the vacuum, similar to a solenoid electromagnet. During the PPM klystron development, several partners (CPI, EEV and Toshiba) have participated by constructing partial or complete PPM klystrons. After early failures during testing of the first two devices, SLAC has recently tested this design (XP3-3) to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW operation came with a tube efficiency of 50%. The XP3 3 average and peak output power, together with the focusing method, arguably makes it the most advanced high power klystron ever built anywhere in the world. Design considerations and the latest testing results for these latest prototypes will be presented.
TUPKF065	Comparison of Klystron and Inductive Output Tubes (IOT) Vacuum-electron Devices for RF Amplifier Service in Free-electron Laser	plasma, impedance, booster, focusing	1093
	A. Zolfaghari, P. MacGibbon, W. North MIT/BLAC, Middleton, Massachusetts
	The MIT X-Ray Laser project, conceived to produce output in the 0.3 to 100 nanometer range, is based on a super-conducting 4-GEV linear accelerator, using 24 multi-cavity cryo-modules, each with its own dedicated RF amplifier, operating at 1.3 GHz. The continuous output of each amplifier is nominally 15 kW, with an optional repetitive pulse-modulation mode of 0.1 second pulse duration at one pulse per second. Although there are no fundamental restraints which preclude the consideration of any RF amplifier type, including solid-state or conventional triode or tetrode, the most appropriate current technology includes the Klystron and the IOT (Inductive Output Tube), also known by the CPI trade-name, Klystrode. The mechanisms by which the devices convert DC input power into RF output power are discussed. The devices are then compared with regard to availability (developmental or off-the-shelf), conversion efficiency, means of pulse-modulation, RF power gain, phase and amplitude stability (pushing factors), and acquisition and life-cycle costs.
THPLT026	Beam Profile Measurements at PETRA with the Laserwire Compton Scattering Monitor	antiproton, laser, gun, target	2526
	T.  Kamps BESSY GmbH, Berlin K. Balewski, H.-C. Lewin, S. Schreiber, K. Wittenburg DESY, Hamburg G.A. Blair, G. Boorman, J. Carter, F. Poirier Royal Holloway, University of London, Surrey S.T. Boogert UCL, London T. Lefevre CERN, Geneva
	The vertical beam profile at the PETRA positron storage ring has been measured using a laserwire scanner. A laserwire monitor is a device which can measure high brilliant beam profiles by scanning a finely focused laser beam non-invasively across the charged particle beam. Evaluation of the Compton scattered photon flux as a function of the laser beam position yields the transverse beam profile. The aim of the experiment at PETRA is to obtain the profile of the positron beam at several GeV energy and several nC bunch charge. Key elements of laserwire systems are currently being studied and are described in this paper such as laser beam optics, a fast scanning system and a photon calorimeter. Results are presented from positron beam profile scans using orbit bumps and a fast scanning scheme.
THPLT027	Optical Transition Radiation Based Beam Diagnostics at the BESSY Synchrotron Radiation Source and FEL Accelerators	antiproton, gun, target, lattice	2529
	T.  Kamps, K. Holldack, P. Kuske BESSY GmbH, Berlin
	Optical Transition Radiation (OTR) based diagnostics tools are widely used in linear accelerators to measure beam parameters like transverse beam size and emittance. Design ideas for OTR stations in the linac section of the BESSY FEL facility are presented. Several key components will be tested in the transfer lines of the BESSY storage ring. Furthermore a novel type of OTR monitor is introduced which enables the measurement of the transverse overlap of seed laser and electron beam in the undulator sections of the linac based FEL facility. Here a special radiator screen will be used allowing simultaneous imaging of both beams in the same optical readout channel.
THPLT028	High Precision Cavity Beam Position Monitor	antiproton, gun, target, lattice	2532
	A. Liapine, H. Henke TET, Berlin
	A cavity beam position monitor is proposed for measuring the beam deflection in the TESLA energy spectrometer. The precision of the measurement has to be better than 1 micrometer. A slotted cavity is chosen as pick-up in order to reject the background signals and enhance the precision and the dynamic range of the monitor. The paper gives the design overview for two prototypes with operating frequencies of 1.5 GHz and 5.5 GHz, respectively. The results obtained on the test bench with direct conversion electronics are presented. A resolution of about 100 nm was achieved.
THPLT029	Parallel Particle in Cell Computations with GdfidL	antiproton, gun, target, lattice	2535
	W. Bruns WBFB, Berlin
	The electromagnetic field solver GdfidL has been extended to compute with free moving charges. For computing in parallel, GdfidL partitions the computational volume in many small subvolumes. Each processor computes the electromagnetic field in its part of the whole volume. In addition to the normal field update equations, the movement of the particles must be computed from the Lorentz-force, and the convection current due to the moving charges must be computed and be used to change the electric field near the particle. For each particle, these computations are performed by the processor which is responsible for the volume where the particle is in. Details of the parallel implementation of the used algorithm, Particle in Cell, are given.
THPLT030	A Novel Device for Non-intersecting Bunch Shape Measurement at the High Current GSI-Linac	antiproton, gun, target, lattice	2538
	P. Forck, C. Dorn, M.H. Herty, P. Strehl GSI, Darmstadt V. Peplov RAS/INR, Moscow S. Sharamentov ANL, Argonne, Illinois
	Due to the high current of heavy ions accelerated at the UNILAC at GSI, non-intersecting beam diagnostics are mandatory. For bunch length and bunch structure determination in the range of 0.3 to 5 ns a novel device has been realized. It uses the time spectrum of secondary electrons created by atomic collisions between beam ions and residual gas molecules. These electrons are accelerated by an electric field of 400 V/mm toward an electro-static energy analyzer. The analyzer is used to restrict of the effective source region. Then the electrons are deflected by an rf-resonator running in phase with the acceleration frequency (36 or 108 MHz) to transform the time spectrum into spatial separation. The detection is done with a multi-channel plate equipped with a phosphor screen and observed by a digital CCD camera. The achieved time resolution is at least 50 ps, corresponding to 2 degree of rf frequency. The general layout of the device and first results will be presented.
THPLT031	Comparison of Rate Equation Models for Equilibrium Beam Parameters	antiproton, gun, lattice, wiggler	2541
	R.W. Hasse, O. Boine-Frankenheim GSI, Darmstadt
	We calculate equilibrium beam parameters from the counteraction of intrabeam scattering (IBS), electron cooling (EC) and target interaction for typical beams in the GSI cooler storge ring ESR and in the proposed HESR. This work is complementary to kinetic modeling efforts at GSI. We developed an easy to use simulation tool that includes various models for the EC rates and the IBS rates, averaged of the detailed ring lattices. The obtained scaling of the equilibrium parameters with beam current and energy are compared with existing experimental data from the ESR and with kinetic simulation results for the HESR.
THPLT032	Computer Controlled Beam Diagnostics for the HICAT Facility	antiproton, gun, lattice, wiggler	2544
	M. Schwickert, A. Peters GSI, Darmstadt
	A set of 93 diagnostic devices for beam diagnostics in the heavy ion cancer therapy facility (HICAT) at the university hospital in Heidelberg is currently under development at GSI. For the HICAT facility that is presently under construction, all beam diagnostic devices are fully computer controlled and allow an automated detection of all relevant beam parameters. The HICAT rasterscan method with active variation of intensity, energy and beam size requires the exact knowledge of the time resolved and spatial structure of the ion beam. An overview of the integrated devices is presented and the intensity measurement of both, the DC and AC beam in the different parts of the accelerator facility are reviewed. Additionally, the timing and control of the diagnostic devices are described.
THPLT033	The Heavy Ion Gantry of the HICAT-facility	antiproton, ion, gun, lattice	2547
	U. Weinrich, R. Fuchs GSI, Darmstadt P. Emde MAN Technologie AG, Mainz
	The Heavy Ion Cancer Therapy Project HICAT at the University Hospital of Heidelberg is under construction. One unique feature of the treatment facility is the first heavy ion gantry in the world. The Gantry will allow the patient treatment with different ion species up to 430 MeV/u with full geometrical flexibility. This functionality has to be maintained for up to 300 000 rotations over the envisaged life cycle of 15 years. GSI has taken the responsibility to coordinate the design and construction of all the different required components. At the time of the conference the design will be finished and the construction started. The contribution will report on challenging construction items like the survey and alignment strategy, safety aspects, flexibility of the ion optics. In order to gain confidence on the principle a test bench with the last part of the gantry was already mounted in a fixed manner at GSI and beam measurements were performed. The results of these tests will also be reported.
THPLT034	Implementation of Higher Order Moments for Beam Dynamics Simulation with the V-Code	antiproton, ion, gun, lattice	2550
	W. Ackermann, T. Weiland TEMF, Darmstadt
	Based on the moment approach V-Code is implemented to simulate charged particle beam dynamics in linear accelerators. Its main aim is to perform elementary studies in those cases when the beam can be considered as a whole and thus making the motion of individual particles negligible in the overall view. Therefore an ensemble of particles can be well described by the moments of its phase-space distribution and the regarded order influences naturally the achievable accuracy as well as the computational effort. Since the well known moment equations generally are not closed, a technique to limit the number of involved moments has to be applied. So far all moments up to the second order have been considered whereas higher order moments are truncated. As a further step towards higher accuracy the influence of higher order moments has to be investigated. For this reason additional third-order equations are implemented into the V-Code and the achieved results are compared with previous second-order-based ones as well as with higher order approximations.
THPLT035	Development of a 3D-Gun-Code based on a Charge Conserving Algorithm	antiproton, ion, electron, simulation	2553
	E. Gjonaj, J. Mudiganti, T. Weiland TEMF, Darmstadt
	Recent efforts in the development of electron sources are aiming at high intensity electron beams, beyond the limitations posed by space-charge effects in conventional guns. Field emitter arrays, multi-beam and sheet-beam guns are a few examples of emerging technology, which require an accurate characterization of the limiting current in complicated 3D-geometry. The newly developed gun code at the Technische Universität Darmstadt, implements a novel approach to the numerical simulation of space-charge-limited electron emission, which is based on the local conservation of charge for arbitrary cathode surfaces. It is shown that, imposing exact charge conservation using the CAD-data of the geometry eliminates the spurious oscillations in the charge density, which typically arise when the piecewise-planar diode approximation is applied in the simulation. The accuracy of this approach is demonstrated in the validation study of a spherical diode and in the large-scale simulation of a Traveling Wave Tube amplifier.
THPLT036	New Discretization Scheme for Wake Field Computation in Cylindrically Symmetric Structures	antiproton, ion, electron, simulation	2556
	R. Hampel, T. Weiland, I. Zagorodnov TEMF, Darmstadt
	Collective effects due to wake fields are a limiting factor in almost every new front line accelerator. Since the early 80's computer codes such as TBCI and MAFIA have been developed for computing wake fields in realistic accelerator structures. With the advent of linear collider studies and small wavelength FEL projects these codes had to face a severe limitation. For the very short bunches in these new accelerators combined with the need for an analysis of very long sections the discrete dispersion became a serious drawback. This effect of having only discrete field values rather than continous ones can be overcome by special algorithms such as semi-implicit integrators as used e.g. in the wake field code ECHO. In this paper we present a new explicit approach which combines the advantage of explicit algorithms (fast) with the absence of dispersion in beam direction.
THPLT037	Investigation of Numerical Noise in PIC-Codes	antiproton, ion, electron, simulation	2559
	S. Schnepp, S. Setzer, T. Weiland TEMF, Darmstadt
	For a detailed analysis of the dynamics of space charge dominated beams a combination of Particle-in-Cell methods with efficient FDTD schemes is widely used. Besides the calculation of the forces acting on the particles the interaction of the beam itself with the surrounding geometries is taken into account. A drawback of this method is its sensitivity to numerical noise in the spectral range nearby the grid cutoff frequency. In this paper we will present results of detailed studies of the impact of the bunch shape on the level of the numerical noise. Furthermore an a priori scheme for efficient noise suppression is derived which does not affect the FDTD update algorithm.
THPLT038	The Synchrotron Radiation Interferometer using Visble Light at DELTA	antiproton, ion, synchrotron, simulation	2562
	U. Berges, K. Wille DELTA, Dortmund
	Synchrotron radiation sources such as DELTA, the Dortmund electron accelerator, rely on a monitoring system to measure the beam size and emittance with sufficient resolution. The resolution limits of the different types of optical synchrotron light monitors at DELTA have been investigated. The minimum measurable beam size with the standard synchrotron light monitor using visible light at DELTA is appr. 80 μm. Due to this limitation an interferometer was built up and tested using the same beamline in the visible range. A minimum measurable beam size of appr. 8 μm could be obtained, which gives an increased resolution of one order of magnitude with the new system.
THPLT039	SVD Based Orbit Correction Incorporating Corrector Limitations at DELTA	antiproton, ion, synchrotron, simulation	2565
	M. Grewe, P. Hartmann, G. Schmidt, K. Wille DELTA, Dortmund
	Singular Value Decompostion (SVD) of the orbit response matrix has become an invaluable tool for orbit correction at storage rings worldwide. SVD based orbit correction has now been realised at DELTA, a 1.5 GeV electron storage ring. However, due to special orbit demands at DELTA and possibly by magnetic imperfections within the storage ring, we frequently have to face corrector limitations during the process of orbit correction. This work focuses on presenting an analytic algorithm on how to treat these limitations when seeking for an optimal SVD based orbit correction. In contrast to previously published methods, this approach is fairly easy to implement and does not afford an numerical solver. Concepts and results will be presented.
THPLT041	Beam Test Stand of the RFQ-drifttube-combination for the Therapy Center in Heidelberg	antiproton, synchrotron, simulation, lattice	2568
	A. Bechtold, M. Otto, U. Ratzinger, A. Schempp, E. Vassilakis IAP, Frankfurt-am-Main B. Schlitt GSI, Darmstadt
	A beam test stand for the Heidelberg medicine RFQ has been installed at the IAP in Frankfurt. The installation consists of a 8 keV/u H+ duoplasmatron ion source, the 400 keV/u RFQ itself and several diagnostic elements comprising a slit-grid emittance measurement system for scanning the transverse beam profile and a bending magnet for measuring the longitudinal beam properties. The test installation will be described in detail, first measurements will be presented and compared to corresponding beam dynamic simulations.
THPLT042	Automated Orbit Control for the HERA ep Collider	antiproton, synchrotron, simulation, lattice	2571
	S.W. Herb, P.K. Bartkiewicz, F. Brinker, J.M. Maass DESY, Hamburg
	Successful operation of the HERA electron-proton collider requires maintaining stable orbits during the typically 12 hour luminosity runs, as well as during the fill and acceleration procedures. The primary sources of orbit errors for the electron ring are the interaction region magnets, whose support structures are integrated with the experimental detectors and susceptible to thermal and magnetic effects. The orbit correction algorithms are designed to correct these effects locally, while operating with somewhat reduced sensitivity on error sources in the rest of the ring. We describe the correction system and our operating experience.
THPLT043	Development of a New Orbit Measurement System	antiproton, synchrotron, simulation, lattice	2574
	O. Kaul, F. Brinker, R. Neumann, R. Stadtmüller DESY, Hamburg
	Since DORIS III became a dedicated source for synchrotron radiation in 1993, the demands of the synchrotron-light-users concerning the beam position stability have permanently increased.In order to improve this stability, different measures have been adopted, all with success. The vacuum chambers have been renewed, since they were the source of quadrupole movement, which caused strong horizontal orbit distortion. In 2003 a new orbit position control was implemented, based on the ?Singular Value Decomposition? method. The position information comes from synchrotron light monitors, installed in the beam-lines, and from the orbit measurement system, which operates with a maximal measurement rate of 5Hz and a spatial resolution not less than 20μm. To satisfy the requirements for beam-position stability, the orbit measurement system has been further developed. The test stage is nearly finished and the new system will be installed soon. The orbit measurement rate will exceed 250Hz und the spatial resolution will be less than 2μm. In addition beam oscillations of up to 20Hz can be damped.
THPLT044	Measurement of the Transverse Coherence of the TTF Free Electron Laser	antiproton, undulator, synchrotron, radiation	2577
	R. Ischebeck, M. Tonutti RWTH, Aachen J. Feldhaus, E. Saldin, E. Schneidmiller, K. Tiedtke, R. Treusch DESY, Hamburg C. Gerth CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire P. Schmüser Uni HH, Hamburg M.V. Yurkov JINR, Dubna, Moscow Region
	The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.
THPLT045	A more Accurate Approach to Calculating Proton Bunch Evolution under Influence of Intra-beam Scattering in a Storage Ring.	antiproton, undulator, synchrotron, radiation	2580
	I.V. Agapov, F.J. Willeke DESY, Hamburg
	Some perturbations of discrete nature are known to influence the performance of a proton storage ring, contributing to parasitic background, decay of beam currents and bunch tail buildup. Such are, for example, intra-beam scattering and residual gas scattering .These processes are to a big extent described by existing analytical theory. The latter, employing a large amount of averaging, usually neglects effects arising from system nonlinearity. So, the motion of tail particles in the presence of a sufficiently nonlinear RF voltage under influence of intra-beam scattering strongly deviates from the average across the bunch and the analytical approach seems inadequate for it. To overcome this situation we have developed more accurate numerical methods for calculations of bunch evolution under influence of a rather broad class of jump-like perturbations. Here we present the computational algorithms and their application to assessment of coasting beam and proton background in HERA-p.
THPLT046	The Synchrotron Radiation Beamline at TTF2	antiproton, radiation, scattering, simulation	2583
	O. Grimm, S. Casalbuoni, L. Fröhlich, O. Peters, J. Rossbach DESY, Hamburg
	The VUV-FEL at DESY, Hamburg, will require novel techniques to characterize the longitudinal charge distribution of the electron bunches that drive the free-electron laser. Conventional methods are inadequate at the short bunch lengths that will be obtained. One technique under study uses coherent far-infrared radiation to reconstruct the bunch shape through Fourier analysis of the spectrum. In a first step, a beam line to guide both far-infrared (50-1000 um) and optical synchrotron radiation from one of the bunch compressor magnets of the linear accelerator to a diagnostic station outside of the controlled area is currently under construction. It will also allow a comparison between streak camera and far-infrared measurements for features on length scales above some 100 um (the streak camera resolution). Later, infrared techniques extending to shorter wavelengths, i.e. to shorter bunch lengths, will also be used further downstream the accelerator, employing synchrotron, transition and undulator radiation. The beam line design, measurement principle and first measurements will be presented.
THPLT047	Beam Position Monitor Development for the IThemba LABS Cyclotron Beamlines	antiproton, radiation, scattering, simulation	2586
	J. Dietrich, I. Mohos FZJ/IKP, Jülich A.H. Botha, J.L. Conradie, J.L.G. Delsink, P.F. Rohwer IThemba Labs, Somerset West
	In cooperation of iThemba LABS (South Africa) and Forschungszentrum Juelich the specification of a sensitive tunable rf narrowband beam position monitor system for cyclotron beamlines has been elaborated. iThemba LABS developed and manufactured the four section stripline monitor chamber. The monitor electronics were developed in the Forschungszentrum Juelich-IKP. The electronics consisting of an RF signal processing module (BPM-RF) and a data acquisition and control module (BPM-DAQ) sequentially processes and measures the monitor signals and deliver via serial network calculated horizontal and vertical beam position data. First measurements with cyclotron beam has been performed in the iThemba LABS in November 2003. Changed beam position due to changing different cyclotron parameters could be studied with high accuracy. The resolution of the beam position measurement was better than 0.1 mm with beam currents down to 0.0005 mA.
THPLT048	Progress in 3D Space-charge Calculations in the GPT Code	antiproton, radiation, scattering, simulation	2589
	G. Pöplau, U. Van Rienen Rostock University, Faculty of Engineering, Rostock M.J. de Loos PP, Soest S.B. van der Geer TUE, Eindhoven
	The mesh-based 3D space-charge routine in the GPT (General Particle Tracer, Pulsar Physics) code scales linearly with the number of particles in terms of CPU time and allows a million particles to be tracked on a normal PC. The crucial ingredient of the routine is a non-equidistant multi-grid Poisson solver to calculate the electrostatic potential in the rest frame of the bunch. The solver has been optimized for very high and very low aspect ratio bunches present in state-of-the-art high-brightness electron accelerators. In this paper, we explore the efficiency and accuracy of the calculations as function of meshing strategy and boundary conditions.
THPLT050	End to End Simulations of the RX2 Beam Transport	antiproton, radiation, scattering, simulation	2592
	N. Pichoff, J.-M. Lagniel CEA/DAM, Bruyères-le-Châtel
	RX2 is a project aiming to produce a high flux of X-rays for radiography purpose. We proposed an RF linac using a DC photo-injector producing 20 bunches with 100nC each at 352 MHz. The beam is then injected in 4 RF superconducting cavities and accelerated to 40 MeV. It is then focused on a target producing X-rays. Here is presented the design, the specificities, and the beam simulations from the cathode to the target by coupling 2 multiparticle codes : PARMELA and PARTRAN.
THPLT051	End to End Multiparticle Simulations of the AIRIX Linac	antiproton, radiation, scattering, simulation	2595
	N. Pichoff, A. Compant La Fontaine CEA/DAM, Bruyères-le-Châtel
	AIRIX is a working 3 kA, 20 MeV induction accelerator. It has been designed with an enveloppe code : ENV. A new set of multiparticle codes (PBGUNS, MAGIC, PARMELA and PARTRAN) has been used recently to simulate the beam transport with an higher accuracy especially taking into account the field non-linearities. A dedicated space-charge routine has been written. The calculation results have been compared to experimental measurements.
THPLT052	Measurement of Relative Gas Chamber Pressure in Narrow Straight Section Vacuum Vessels by Observing Gas Bremstrahlung	vacuum, antiproton, radiation, scattering	2598
	G.A. Naylor, B. Joly, D. Robinson ESRF, Grenoble
	The measurement of gas pressure inside long, small cross section, vacuum vessels is difficult due to the distance between the centre of the vacuum vessel and vacuum gauges (leading to a low vacuum conductance). Following initial chamber installation, significant out-gassing is observed leading to a significant pressure bump within the chamber. A modified beam loss detector has been developed in order to monitor the gamma radiation produced by the collision of the 6GeV electrons in the storage ring with residual gas atoms. The narrow beam of gamma radiation is intercepted at various points by high Z materials in the beam line front-end allowing a radiation shower to be detected outside the vacuum vessel proportional to the gas pressure in the corresponding storage ring straight section. Various locations are considerred and results shown.
THPLT053	Fast Orbit Feedback Developments at ELETTRA	vacuum, antiproton, feedback, radiation	2601
	D. Bulfone, R. De Monte, M. Ferianis, V. Forchi', M. Lonza ELETTRA, Basovizza, Trieste
	A number of fast local orbit feedback stations are being sequentially installed at ELETTRA to improve the stability of the electron beam at the Insertion Device source points. They rely on Beam Position Monitors equipped with digital detector electronics that provides high precision and readout rate. The local feedback stations will be integrated in a fast global orbit feedback system, which is the goal of the ongoing developments. The performance and the operational experience gained with the local feedback systems are presented together with the planned road map towards the global system.
THPLT054	Emittance Diluition due to 3D Perturbations in RF Photoinjectors.	vacuum, antiproton, feedback, radiation	2604
	M. Quattromini, L. Giannessi, C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma)
	The predictions from different simulation codes are compared to investigate the effects of non axis-symmetric conditions, fluctuations in cathode's quantum efficiency and other sources of dishomogeneities in the performances of a typical RF photoinjector. The layout includes a RF gun and a focusing solenoid in a configuration aimed at minimizing the emittance growth due to space charge effects.
THPLT055	Longitudinal Phase Space Characterization of the CTF3 Beam with the RF Deflector	vacuum, antiproton, feedback, radiation	2607
	D. Alesini, C. Biscari, A. Ghigo, F. Marcellini INFN/LNF, Frascati (Roma) R. Corsini CERN, Geneva
	The characterization of the longitudinal phase space of the CTF3 beam is an important item for tuning all machine parameters and increase the 30 GHz power production. By means of an RF deflector and a dispersive system the longitudinal phase space can be completely characterized. In this paper we present the simulation of the measurement and the mechanical layout of the full system.