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coupling

     
Paper Title Other Keywords Page
MOOPMA01 Challenges in ILC SCRF Technology superconductivity, linear-collider, controls, monitoring 26
 
  • D. Reschke
    DESY, Hamburg
  With a baseline operating gradient of 31,5 MV/m at a Q-value of 1·1010 the superconducting nine-cell cavities for the ILC are a challenging milestone for SRF technologie. Worldwide intensive ILC R&D programs are underway or in the planning stage in the all three regions of America, Asia and Europe. This paper will give an overview of the main activities in superconducting RF (SRF) technology.  
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TUPMA088 High Power RF Testing of a Cell Coupled Drift Tube LINAC Prototype for LINAC4 linac, klystron, vacuum, pick-up 232
 
  • M. Vretenar, Y. Cuvet, F. Gerigk, J. Marques Balula, M. Pasini
    CERN, Geneva
  A Cell-Coupled Drift Tube Linac (CCDTL) accelerating structure at 352 MHz has been selected for the energy range 40 to 90 MeV of Linac4, a new injector linac for the CERN accelerator complex. With regard to a conventional DTL in this energy range this structure presents the advantages of lower construction cost and easier access, cooling and alignment of the focusing quadrupoles placed between tanks. A full-scale high-power prototype of about 1/3 of a complete module has been designed and built at CERN. It is fed by a waveguide input coupler of novel conception. This paper summarizes the main mechanical features of the prototype and reports the results of low-power and high-power RF testing.  
 
WEZH101 Real Time Feedback on Beam Parameters feedback, controls, synchrotron, collider 295
 
  • R. J. Steinhagen
    CERN, Geneva
  Traditionally, tight beam parameter stability requirements were most pronounced for light sources and lepton colliders but became increasingly important for present and future hadron accelerator operation, not only for performance but also for reasons of machine protection, as recent improvements lead to significantly increased stored beam energies. In the latest generation machines the performance depends critically on the stability of the beam. In order to counteract disturbances due to magnetic imperfections, misalignments, ground motion, temperature changes and other dynamic effects, fully automated control of the key beam parameters –- orbit, tune, coupling, chromaticity and energy -– becomes an increasingly important aspect of accelerator operation. This contribution presents an overview of beam-based feedback systems, their architecture, performance limitations and design choices involved.

invited oral

 
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WEC3H102 Fabrication and Performance Test of the Cavity BPM for KEK ATF2 and PAL XFEL pick-up, resonance, extraction, linear-collider 336
 
  • J. Y. Huang, W. H. Hwang, S. H. Kim, S. J. Park, Y. J. Park
    PAL, Pohang, Kyungbuk
  • Y. Honda, I. Y. Inoue, T. Tauchi, J. Urakawa
    KEK, Ibaraki
  • M. C. Ross
    Fermilab, Batavia, Illinois
  Precise, single shot measurement of the beam position with a sub-micrometer resolution is required for the next generation linear accelerators such as International Linear Collider (ILC) and X-ray Free Electron Laser (XFEL). As a pill-box cavity structure is sensitive to the transverse offset of the beam at the dipole-mode resonance, e.g., TM110-mode, a pill-box type cavity is a good candidate for the sub-micrometer beam position monitor (BPM). Test cavity BPM had been designed and tested in KEK successfully, and miscellaneous improvements for the final prototype fabrication and beam tests are performed in collaboration between KEK, SLAC and PAL. With the successful results of beam test in ATF, 41 cavity BPMs will be produced by PAL and installed in ATF2, which is an advanced beam-test line under construction as the extension of existing ATF for the beam studies on the final focus of the planned ILC program. Technical design considerations, fabrication and test results are described in this paper.  
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WEPMA014 Inhomogenous Field Wien Filter Design proton, focusing, ion, rfq 354
 
  • P. Jain, D. P. Chakravarthy, A. K. Ray, P. Roychowdhury
    BARC, Mumbai
  The Wien velocity filter is a useful device that transports pure proton fraction from high-power ECR proton source to the RFQ. It is a deflecting device having crossed electrostatic and magnetostatic fields both perpendicular to the beam trajectory that deflects and eliminates the undesired species of ions from the main beam. A tilted-pole Wien filter (*) surpasses the classical parallel-rectangular-poles Wien filter in performance as the former eliminates the astigmatism. The present paper describes the design of an inhomogeneous field Wien filter where the equations of motion are developed and solved in a first-order approximation for a paraxial ion beam inside an ExB mass separator without considering the space charge effects. References : (*) New tilted-poles Wien filter with enhanced performance Review of Scientific Instruments 60 (3), March 1989  
 
WEPMA024 A General Model of the Resistive Wall Instability in Linear Accelerators focusing, single-bunch, vacuum, linear-collider 363
 
  • J. R. Delayen
    Jefferson Lab, Newport News, Virginia
  • J. Wu
    SLAC, Menlo Park, California
  A general model for wakefield-generated instabilities in linear accelerators originally developed for cumulative beam breakup is applied here to the resistive wall instability. The general solution for various bunch charge distributions and application to various accelerator configurations will be presented.  
 
WEPMA035 Degradation of the Beam passing through Idle Coupled Cavities impedance, linac, proton, injection 369
 
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  Effects of wake fields on high intensity proton beam are studied, when it passes through idle coupled cavities. There is the same number of frequencies as the number of gaps that consist on the coupled cavity. Since cavities are designed for the accelerated beam, the shunt impedance for each mode is different from the designed value, when the beam is not accelerated. This change of shunt impedances reduces the detuning effect for the reduction of beam degradation.  
 
WEPMA037 Beam Coupling Impedance Studies of the CSNS Ring impedance, kicker, space-charge, extraction 372
 
  • N. Wang, Q. Qin
    IHEP Beijing, Beijing
  The China Spallation Neutron Source (CSNS) is a high intensity proton accelerator with an injection energy of 80 MeV. The knowledge of impedance in the vacuum chamber is necessary for optimizing the accelerator performance. In this paper, the longitudinal and transverse coupling impedances of the CSNS Rapid Cycling Synchrotron (RCS) are estimated.  
 
WEPMA039 Effect of Magnetic Field Coupling On INDUS-2 Quadrupole Magnets quadrupole, simulation, dipole, multipole 378
 
  • G. Sinha, A. Kumar, A. Mishra, G. Singh
    RRCAT, Indore (M. P.)
  The distances between the magnets in the Indus-2, are small and as a result, the magnetic field of one magnet may affect the fields of the adjacent magnets. Therefore, it is important to find out the effect of mutual coupling between magnets in the actual condition in the ring and the ways to overcome this problem. In this paper, we will discuss how the field quality of Quadrupole magnets (QPM) in the ring is affected when accompanied by various corrector dipole magnets (CDM)(vertical and horizontal) and sextupole magnets (SPM). Variation of integrated quadrupole strength in presence of CDM is measured at various field excitations and also by varying the distance between the magnets using a rotating coil. Experimental results are compared with the results obtained from 3D simulations. Possibilities of studying the interference effect by scanning the field by a Hall probe, is explored. Dependence of field interference on the distance between magnets, pole gap and the steel length are studied. Effects of the adjacent magnets on the higher order multipole of QPM are also examined.  
 
WEPMA048 Beam Position Monitor at SCSS Prototype Accelerator undulator, alignment, acceleration, dipole 387
 
  • H. Maesaka, Y. Otake, T. Shintake, K. Togawa
    RIKEN Spring-8 Harima, Hyogo
  • H. Ego, T. Fukui, N. Hosoda, T. Ohshima
    JASRI/SPring-8, Hyogo-ken
  The SCSS X-ray free electron laser (XFEL) project is in progress at SPring-8. The SCSS prototype accelerator for VUV-FEL has been constructed and is in operation. The required resolution of the beam position is less than 1um for XFEL (10um for VUV-FEL). A cavity RF-BPM (Radio Frequency Beam Position Monitor) was developed for the SCSS accelerator based on the past experiment in which the position resolution of several 10nm was achieved. In the prototype accelerator, the beam-based calibration method of the RF-BPM was established. An experiment to evaluate the position resolution was also performed, and the preliminary result was obtained to be less than 5um. This result is sufficient for VUV-FEL. The RF-BPM made important contributions to the tuning of the prototype accelerator such as beam optics measurements and VUV-FEL amplification. By using RF-BPM data, for example, the envelope of the beam trajectory was visualized and the beam was straightly passed through undulators. As a result, VUV-FEL amplification was observed in the wavelength region of 40-60nm.  
 
WEPMA051 Development of Wide Band FCT System for Booster Synchrotron of Indus-1 & 2 pick-up, booster, synchrotron, impedance 396
 
  • P. Pareek, R. S. Shinde, K. Singh
    RRCAT, Indore (M. P.)
  A high precision & non-destructive type of wide band FCT for the measurements of electron current has been developed. This monitoring system is composed of slow & fast FCTs, NiZnCo ferrite toroidal cores, pick up coils, electromagnetic shields & pulse amplifiers. A wide band FCT (rise time 60 ns & decay 1 ms) required for measurement of Electron beam intensity & turn-to-turn observation & stored current accumulation during 1 us pulse injection into Booster Synchrotron. Single FCT can't measure e beam current & turn-by-turn observation from 60 ns to 1 ms. Therefore, we designed & developed two FCTs housed in a single box. The spacing between them is optimized so that coupling between them will not affect pulse shape. The FCT consists of two NiZn ferrite ring cores separable into two pieces for easy setting around ceramic beam duct. A beam intensity of pulse (100 ns ~1 us) beam is monitored by fast rise Current monitor (~ 60 ns)& turn/stored currents monitored by slow FCT (~ 1 us to 1 ms). A wide band FCT showed fast rise & slow decay, high sensitivity (0.050V/mA), linearity within 1 % & good S/N ratio. This paper focuses on FCT designs, construction & their pulse response  
 
WEPMA083 Design of C-band Standing-wave Accelerating Structure bunching, electron, linac, resonance 440
 
  • S. H. Kim, M.-H. Cho, W. Namkung, B. Park, H. R. Yang
    POSTECH, Pohang, Kyungbuk
  • S. D. Jang, J.-S. Oh, S. J. Park, Y. G. Son
    PAL, Pohang, Kyungbuk
  We design a C-band standing-wave accelerating structure for a compact electron linac. It is capable to produce electron beams with the beam energy of 4 MeV and the pulsed beam current of 50 mA. It is to be operated in the π/2 mode with the on-axis coupled structure. The beamline is composed of the E-gun and the accelerating column with 3 and half bunching cells and 9 and half normal cells. We design standing-wave RF cavities using the OMEGA3P code to implement the asymmetric magnetic coupling slots. For the beam dynamics study, we use the PARMELA code with the SUPERFISH fields configuration. Without the pre-buncher cavity and the focusing magnets, the lost beam power to the wall is 10 kW for the output beam power of 200 kW, while the transmission is 58%.  
 
WEPMA122 Design and Development of 30 MeV, 3 kW RF Electron LINAC linac, electron, target, acceleration 491
 
  • V. T. Nimje, D. Bhattacharjee, K. Dixit, D. Jayaprakash, K. C. Mittal, A. K. Ray
    BARC, Mumbai
  A 30 MeV, 3 kW RF Electron linac for neutron generation is being designed and developed. The Design parameters, beam studies etc. will be described in this paper.  
 
WEPMA132 Superconducting Niobium Resonator Fabrication And Testing At IUAC linac, electron, controls, proton 500
 
  • P. N. Prakash, D. Kanjilal, K. K. MISTRI, A. Roy, S. S.K. Sonti, J. Zacharias
    IUAC, New Delhi
  Superconducting niobium resonator fabrication and testing facilities have been developed at Inter-University Accelerator Centre. The facilities are used to construct niobium resonators for the superconducting booster linac as well as for future accelerator development projects. In the first phase a single quarter wave resonator (QWR) was successfully fabricated and tested. In the second phase two completely indigenously built QWRs were constructed. In cold tests at 4.5 K one of them performed at 3.5 MV/m with 3.5 W RF input power, exceeding the nominal design goal. After the successful completion of this project production of fifteen QWRs for the 2nd and 3rd linac modules began. This work has progressed sufficiently and we plan to complete the production by mid ‘2007. In addition to resonator fabrication the facilities have been used for other developments such as a new design of niobium-stainless steel transition assembly, slow tuner modifications, and repairing of the existing QWRs. Details of the activities and performance of the resonators will be presented.  
 
WEPMA133 Evaluation of External Q Using Kroll-Yu Method With Microwaves Studio resonance, impedance, proton, superconductivity 503
 
  • A. S. Dhavale, K. C. Mittal
    BARC, Mumbai
  Design and development of superconducting cavity has been taken up as a part of Accelerator Driven Subcritical project(ADSS). An input coupler is designed for the same using Kroll-Yu method*. The evaluation procedure is optimized and the method has been successfully implemented for the evaluation high external Q**. The validity of the Kroll-Yu method is tested with the external Q calculations by P. Balleyguier method for the Benchmark cavtity which is a pillbox cavity of diameter ~200 mm, length ~150 mm with semi-rigid coaxial line***. It is found that the careful choice of data points provides accurate results over wide range.

* N. M.Kroll, D. U.L. Yu, "Computer determination of the external Q and resonant frequency of waveguide loadaed cavities", SLAC-PUB-5171, Jan1990(A) ** A. S.Dhavale and K. C.Mittal,"Evaluation of external Q of the superconducting cavity using Kroll-Yu method", Review Of Scientific Instruments 77, 066101 (2006)*** P. Balleyguier, "A straightforward method for cavity external Q computation", Particle Accelerators, Vol.57, P.113-127, 1997

 
 
WEPMA137 Design and Simulation of Multibeam Klystron Cavity klystron, simulation, linac, vacuum 509
 
  • A. K. Tiwari, R. K. Arora, P. R. Hannurkar
    RRCAT, Indore (M. P.)
  The klystron amplifier is capable of providing maximum power per unit length. A number of klystrons may be paralleled to get more power output and increased redundancy but phase matching at output remains a troublesome part of any such arrangement. Multibeam klystron provides a solution where all the beams are accelerated through a common voltage and interaction takes place in a common structure namely multibeam cavity so the problem of phase matching no longer exists. The advantage of MBK is low perveance for individual beams and hence higher efficiency. The design and simulation of a multibeam klystron cavity with four beams is presented using electromagnetic code Microwave Studio. R/Q at frequency 350MHz is optimized. The cavity simulated is to be used in 350 MHz, 250 kW CW klystron. This klystron will be used for 100 MeV proton Linac for Spallation Neutron source (SNS). Important Simulation results are described.  
 
WEPMA143 High-Power, Low-Loss, Radial Rf Power Dividers/Combiners impedance, insertion, simulation, controls 520
 
  • A. Jain, A. Gupta, P. R. Hannurkar, D. Sharma
    RRCAT, Indore (M. P.)
  A 20 kW Solid State Power Amplifier (SSPA) at 352 MHz development is in progress at RRCAT. This design uses radial splitting and combining architecture in which the signal is divided into a number of individual parts. Each individual part is then amplified by a respective amplifier of 200 W. The outputs of the amplifiers are then combined into a single output that achieves final output power of the order of 1.5 kW to 4 kW. As a part of this system, two high power combiners have been designed and developed. One is 8 way with output ports opposite to input port. Second one is 16 way with radial output ports. Both of these designs are compact with 20 cm diameter of outer radial disk. Input ports are N connector, while output port is 15/8” rigid coaxial line. Measured performance of these two designs shows insertion loss of 0.6 dB and input VSWR of 1.09. Radial architecture uses in-phase, non-resonant radial transmission line structures.  
 
THYMA04 Development of Quarter Wave Resonators linac, controls, damping, vacuum 554
 
  • A. Roy
    IUAC, New Delhi
  The accelerating structure for the superconducting linac booster for the 15 UD Pelletron at IUAC is a Nb QWR cavity, designed and fabricated as a joint collaboration between IUAC and ANL, USA. Initial cavities required for the first linac module were fabricated at ANL. For fabrication of cavities required for future modules a Superconducting Resonator Fabrication Facility has been set up at IUAC. Three quarter wave resonator (QWR) cavities have been fabricated and fifteen more resonators for the second and third linac modules are in advanced stage of completion. This facility has allowed us to undertake repairs on some of the resonators which sprung leaks. First experiment with the accelerated Si beam through the first linac module having eight resonators along with a superconducting solenoid have been conducted recently.  
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THC3H101 Status of the Industrial RF-accelerators in BINP electron, extraction, vacuum, shielding 622
 
  • V. Auslender, A. A. Bryazgin, V. G. Cheskidov, B. L. Faktorovich, V. Gorbunov, I. V. Gornakov, V. E. Nekhaev, A. D. Panfilov, A. I. Sidorov, V. O. Tkachenko, A. F.A. Tuvik, L. A. Voronin
    BINP SB RAS, Novosibirsk
  ILU type of industrial RF accelerators developed and producing in BINP involve the energy range from 0.5 to 5 MeV with power up to 50 kWt. Compact size of this type of the accelerators and no necessity of SF6 allows to use their in the wide spectrum of technology, including the food and drug treatment. Described the status of the novel ILU-12 accelerator with energy up to 5 MeV and power up to 300 kWt. BINP developed series of X-ray converters based on tantalum and wolfram targets. The family of ILU accelerators includes the ion accelerator ILU-9. This report involves the new radiation technologies which use ILU type of accelerators, based on e-beam, X-ray and ion beams.  
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THPMA008 Field Measurement Results of the Quadrupole Magnets for ATF2 quadrupole, sextupole, extraction, power-supply 637
 
  • M. Masuzawa, Y. Suetsugu, R. Sugahara
    KEK, Ibaraki
  ATF2 will be built at KEK as a test facility for the final focus system for the ILC. The specifications for the final focus system require transverse focusing of the electron beam to be nearly 40 nm. The quadrupole magnets for the ATF2 beam line have been designed and manufactured. The diameter of the magnet bore is 32 mm and the length is 180 mm. The magnets have to meet strict specifications for the multipole components, especially the sextupole components, in order to achieve the required small beam size. Precision measurement is required not only for the multipole components but also for the magnetic center and median plane. Field measurement results of these small bore magnets will be reported.  
 
THPMA085 Mechanical Coupling between the LHC Cryogenic Distribution Line and the Short Straight Section housing the Superconducting Quadrupole. Theoretical Analysis and Experimental Validation vacuum, alignment, collider, hadron 758
 
  • S. Dutta, S. C. Bapna, J. Dwivedi, S. Kotaiah, A. Kumar, R. S. Sandha, H. C. Soni
    RRCAT, Indore (M. P.)
  • C. Garion, A. Poncet, B. Skoczen
    CERN, Geneva
  The cryogenic module of the Short Straight Section (SSS) of Large Hadron Collider (LHC) is supplied with liquid & gaseous Helium through a jumper connection, which links the valve distribution box of the Cryogenic Distribution Line (QRL) & the SSS. The internal as well as external features of the jumper construction allow for sufficient flexibility to reduce the reaction forces responsible for elastic deformations when the SSS is moved for alignment. The SSS is composed of a cold mass and an external vacuum vessel equipped with fiducials for allowing the precise alignment of the machine when the cryostat is finally closed. A deformation of the structure from reaction forces induced by relative displacements of the SSS and the QRL, if unpredictable, would result in a dangerous misalignment of the quadrupole magnetic axis. A unified FE model, validated by a 40 meter long dedicated test setup at CERN, was generated at RRCAT to study the elastic behaviour of the SSS under the conditions of alignment. Transfer functions linking the action on the SSS external alignment jacks and the position of the cold mass are now available that will be used to properly align the machine in operation.  
 
FRXMA03 Achievement of ATF and its Future Plans damping, emittance, kicker, extraction 837
 
  • J. Urakawa
    KEK, Ibaraki
  The ATF (Accelerator Test Facility at KEK) International collaboration has been launched formally under the MoU (Memorandum of Understanding) from August 1, 2005, so as to maximally contribute to the world design and development efforts in the areas of particle sources, damping rings, beam focusing and beam instrumentation towards the International Linear Collider (ILC) project. I will give a talk on the recent achievement at ATF and its future plans, especially ATF2 project.