| Paper | Title | Other Keywords | Page | ||
|---|---|---|---|---|---|
| MO2001 | Status of the CLIC Test Facility (CTF3) | linac, klystron, beam-loading, extraction | 11 | ||
|
The CTF3 project, being built within the frame-work of an international collaboration involving more than 12 institutions, is advancing as planned. To date, the electron linac with its sub-harmonic bunching system, the magnetic chicane for bunch-length variations, and the Delay Loop have been installed. The 1.5 GHz sub-harmonic bunching system with fast phase switching allows the longitudinal position of the bunches to be changed every 140 ns. This phase-coded beam has been successfully injected into the Delay Loop using an RF deflector and bunch interleaving of 140 ns long sub-bunch trains which double the bunch repetition frequency has been demonstrated in the extraction line. In addition to its role as a test bed for the CLIC RF power source, CTF3 is being used as a source of high-power RF at 30 GHz for the testing of CLIC accelerating structures. In this power-generating mode, about 100 MW of 30 GHz power is routinely extracted from the beam half-way up the linac by special-purpose power-extracting structures and transported to the high-gradient test area by low-loss waveguides. This paper describes the overall status of the CTF3 project and outlines the plans for the future.
|
|
|
||
| MOP002 | Efficient Long-Pulse, Fully Loaded CTF3 Linac Operation | linac, beam-loading, klystron, gun | 31 | ||
|
An efficient RF to beam energy transfer in the accelerating structures of the drive beam is on of the key points of the Compact Linear Collider (CLIC) RF power source. For this, the structures are fully beam-loaded, i.e. the accelerating gradient is nearly zero at the downstream end of each structure. In this way, about 96% of the RF energy can be transferred to the beam. To demonstrate this mode of operation, 1500 ns long beam pulses are accelerated in six fully loaded structures in the CLIC Test Facility (CTF3) Linac. In the paper we present the results of experimental studies on this mode of operation, compare them with theoretical predictions and discuss its potential use in CLIC.
|
|
|
||
| MOP016 | SRF Linac Solutions for 4GLS at Daresbury | linac, damping, electron, superconducting-RF | 64 | ||
|
The proposed 4th Generation Light Source (4GLS) facility, anticipated to be located at Daresbury Laboratory in the UK, will extensively utilise Superconducting RF (SRF) Linacs for each stage of its multi-beam acceleration. IR, XUV and VUV FEL devices, and particularly the ability to combine these sources for users, provide a unique capability for this Energy Recovery Linac (ERL) based accelerator. The CW mode of operation for the SRF Linacs necessitates that adequate provision is made for delivering the required RF power and also damping of the beam induced HOMs to manageable levels. This paper outlines the RF requirements and proposed solutions for each of the 4GLS Linacs.
|
|
|
||
| MOP018 | Upgrading the CEBAF Accelerator to 12 GeV: Project Status | controls, linac, beam-transport, dipole | 70 | ||
|
Jefferson Lab is preparing to upgrade its 6 GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV as part of the 12 GeV Upgrade project. The doubled energy will significantly extend the scientific reach of the three existing Halls with upgraded experimental equipment, and will make possible a new research program in exotic mesons in a newly constructed fourth Hall. The acceleration of the present linacs will be roughly doubled through the addition of ten new cryomodules with performance ~5 times the original specification for CEBAF. The 2K helium plant will be roughly doubled; new rf systems, including digital controls, will be installed for the new cryomodules. The beam transport system’s capability will be doubled by strongly leveraging existing hardware (without incurring significant saturation) but must be enhanced with some replacement magnets, new power supplies, one new recirculation arc, and a beamline to the new Hall. Critical Decision 1 was approved by DOE for this project in February 2006. Technical status for the accelerator systems including R&D will be presented as well as the status of the 12 GeV Upgrade Project as a whole.
|
|
|
||
| MOP025 | Study on High-Current Multi-Bunch Beam Acceleration for KEKB Injector Linac | klystron, linac, beam-loading, simulation | 91 | ||
|
The KEKB injector linac is usually operated to accelerate only two 10 nC electron bunches to generate positron, since more bunch cannot be equalized the beam energy using the conventional pulse compressor (SLED) and the simple phase modulation. The aim of this study is to find how to accelerate more bunches without any modification of high power RF distribution. One way is that a part of the acceleration units is used to compensate the beam energy difference. On the other hand, the recent electron linac is designed for the multi-bunch operation by compensating the beam loading. And this beam loading compensation method is usually realized by combining the output power of two or more klystrons. However our linac system consists of one 50 MW klystron in one acceleration unit, and eight klystrons are driven by a 100kW klystron. Another way to realize the multi-bunch acceleration in our linac is using the amplitude modulation of the klystron. This is realized using the I-Q modulation of the low level RF considering the non-linear characteristics of the total amplification system including klystrons. Further we developed a FPGA board with 100 MHz DACs and ADCs to realize this.
|
|
|
||
| MOP028 | Creation of Peaks in the Energy Spectrum of Laser-Produced Ions by Phase Rotation | laser, proton, target, ion | 97 | ||
|
Efficient acceleration of ions with use of very high electromagnetic field created by a high power laser has been paid attention because of its attainable very high acceleration gradient. Its intensity, however, has exponentially decreases according to the increase of its energy, which causes essential difficulty for its real application. For the quality improvement of laser-produced ions in their energy spreads, a scheme to apply an additional RF electric field synchronous to the pulse laser, called “Phase Rotation”,* has been applied to the ions produced from the thin foil target 3 and 5 mm, in thickness by irradiation of focused Ti:Sapphire laser with the wave length of 800 nm after optimization of the ion production process with use of real time observation of ion energy by TOF measurement.** Energy peaks with the spread of 7 % have been created in the energy spectrum at the positions depending on the relative phase between the pulse laser and the RF electric field. Possible application of “Phase Rotated” laser-produced ion beam is also to be discussed.
|
* A. Noda et al., Laser Physics, Vol. 16, No.4, pp.647-653(2006). |
|
||
| MOP030 | An Upgrade to NSCL to Produce Intense Beams of Exotic Nuclei | cyclotron, linac, ion, injection | 103 | ||
|
A substantially less costly alternative to the Rare Isotope Accelerator (RIA) project has been developed at Michigan State University (MSU). By upgrading the existing facility at the National Superconducting Cyclotron Laboratory (NSCL), it will be possible to produce stable beams of heavy ions at energies of greater than 180 MeV/u with beam power in excess of >80 kW. The upgrade will utilize a cyclotron injector and superconducting driver linac at a base frequency of 80.5 MHz. Radioactive ion beams will be produced in a high-power target via particle fragmentation. A charge-stripping foil and multiple-charge-state acceleration will be used for the heavier ions. The 9 MeV/u injector will include an ECR source, a bunching system, and the existing K1200 superconducting cyclotron with axial injection. The superconducting driver linac will largely follow that proposed by MSU for RIA, using cavities already designed, prototyped, and demonstrated for RIA. The existing A1900 Fragmentation Separator and experimental areas will be used, along with a new gas stopper and reacceleration system.
|
|
|
||
| MOP042 | Performance of Alternating-Phase-Focused IH-DTL | linac, ion, rfq, heavy-ion | 136 | ||
|
Tumor therapy using HIMAC has been performed at NIRS since June 1994. With the successful clinical results over more than ten years, a number of projects to construct these complexes have been proposed over the world. Since existing heavy-ion linacs are large in size, the development of compact linacs would play a key role in designing compact and cost-effective complexes. Therefore, we designed a compact injector system consisting of RFQ and Interdigital H-mode DTL (IH-DTL) having the frequency of 200 MHz. For the beam focusing of IH-DTL, the method of Alternating-Phase-Focusing (APF) was employed. By using APF, no focusing element in the cavity, such as quadrupole magnets, is needed. Having employed APF IH-DTL, the injector system is compact; the total length of two linacs is less than 6m. The injector system can accelerate carbon ions up to 4.0 AMeV. The construction and installation of RFQ and APF IH-DTL has completed, and the beam tests were performed. We succeeded to accelerate carbon ions with satisfactory beam intensity and emittances. The design and performance of RFQ and APF IH-DTL will be presented.
|
|
|
||
| MOP043 | Upgrade of 1-MeV Heavy Ion ISR RFQ Accelerator | ion, rfq, ion-source, simulation | 139 | ||
|
The upgrade of 1 MeV ISR RFQ accelerator has been launched for exploring the possibilities of a few mA heavy ion beam acceleration and its applications on the material science, biological irradiation and RFQ-AMS carbon chronology. A new ECR ion source with extracting voltage of 22kV, and the LEBT matching section have been redesigned and tested to increase the injection beam current and to realize the beam matching. The experimental tests for the different operating parameters have been compared to the simulations by self developed code RFQDYN. The preliminary results will be presented in this paper.
|
|
|
||
| TUP030 | RF Cavity Performance and RF Infrastructure for the ISAC-II Superconducting Linac | linac, controls, coupling, power-supply | 309 | ||
|
The ISAC-II superconducting linac is presently being commissioned. Twenty cavities have been prepared and characterized in single cavity tests before mounting in the on-line cryomodules. The cavities are specified to operate at a challenging peak surface field of 30MV to supply an accelerating voltage of 1.1MV/cavity. The cavity bandwidth of ±20Hz is achieved by overcoupling while a mechanical tuner actively maintains the cavity frequency within this bandwidth. An overview of the rf systems will be given. We will describe the early operating experience and compare the cavity on-line performance with the single cavity characterizations.
|
|
|
||
| TUP031 | Beam Dynamics Studies on the ISAC-II Superconducting Linac | linac, emittance, bunching, diagnostics | 312 | ||
|
The ISAC-II superconducting linac is presently in the beam commissioning phase. The linac lattice consists of modules of four quarter wave cavities and one superconducting solenoid. Beam steerers between cryomodules compensate for steering effects due to misalignments in the solenoids. Beam dynamics aspects of linac commissioning will be highlighted.
|
|
|
||
| TUP032 | Comparison of SNS Superconducting Cavity Calibration Methods | SNS, beam-loading, controls, pick-up | 315 | ||
|
Three different methods have been used to calibrate the SNS superconducting cavity RF field amplitude. Two are beam based and the other strictly RF based. One beam based method uses time-of-flight signature matching (phase scan method), and the other uses the beam-cavity interaction itself (drifting beam method). Both of these methods can be used to precisely calibrate the pickup probe of a SC cavity and determine the synchronous phase. The initial comparisons of the beam based techniques at SNS did not achieve the desired precision of 1% due to the influence of calibration errors, noise and coherent interfaces in the system. To date the beam-based SC cavity pickup probe calibrations agree within approximately 4%, comparable to the conventional RF calibrations.
|
|
|
||
| TUP034 | Development of a Superconducting RF Module for Acceleration of Protons and Deuterons at Very Low Energy | vacuum, proton, alignment, linac | 321 | ||
|
A prototype superconducting accelerating module housing six 176 MHz half wave resonators and three superconducting solenoids is currently under production at Accel as part of a 40 MeV linear accelerator at the Soreq NRC. The module will accelerate protons and deuterons from energy of 1.5 MeV/u up to 6.5 MeV. The design is based on a peak electric field gradient of 25 MV/m and maximum 10 W of power dissipation in the helium bath by each cavity. Main design considerations of the cavities, solenoids, tuners and couplers as well as for the module especially in view of assembly and alignment will be presented. First cold cavity test results obtained in Accel’s new cold RF test facility will be presented. Prototypes of the tuner, helium vessel, solenoids and the couplers are under construction and partly under test.
|
|
|
||
| TUP081 | Impact of a RF Frequency Change on the Longitudinal Beam Dynamics | linac, emittance, focusing, ion | 447 | ||
|
A frequency jump in a high-intensity linac could have some impact on the longitudinal beam dynamics and could therefore introduce some filamentation and even some beam loss if the transition is not done properly. This point is especially important when comparisons of cavity performances are performed. We show in this paper two techniques in order to render transparent for the beam such frequency jump. A few examples which show the efficiency of the two techniques are given.
|
|
|
||
| TUP090 | Advances of NPK LUTS Contraband Detection System | rfq, proton, linac, radiation | 472 | ||
|
Principle and project of NPK LUTS contraband detection technological complex (CDTC) was presented by authors at EPAC 2002. This paper reviews researches connected with 433 MHz ion linacs creation for the last four years. Main part is description of designing and testing of RFQ and APF resonators. State of affairs of other CDTC system is described briefly.
|
|
|
||
| WE2001 | Neutralized Drift Compression Experiments (NDCX) | plasma, ion, simulation, vacuum | 492 | ||
|
Intense ion beams offer an attractive approach to heating dense matter uniformly to extreme conditions, because their energy deposition is nearly classical and volumetric. Simultaneous transverse and longitudinal beam compression, in a neutralizing plasma medium, along with rapid beam acceleration, are being studied as a means of generating such beams, which will be used for warm dense matter (WDM), high energy density physics (HEDP), and fusion studies. Recently completed experiments on radial and longitudinal compression demonstrated significant enhancements in beam intensity. In parallel with beam compression studies, a new accelerator concept, the Pulse Line Ion Accelerator (PLIA), potentially offers cost-effective high-gradient ion beam acceleration at high line charge density. We report experimental results on beam neutralization, neutralized focusing, neutralized drift compression from a series of experiments. We also report energy gain and beam bunching in the first beam dynamics validation experiments exploring the PLIA.
|
|
|
||
| TH1003 | Initial Commissioning Results from the ISAC-II SC Linac | linac, emittance, ion, heavy-ion | 521 | ||
|
TRIUMF has installed 20MV of superconducting heavy ion linac as part of the first phase of the ISAC-II project. The linac consists of five cryomodules each with four 106MHz quarter wave cavities and one superconducting solenoid. The cavities and ancillaries operate cw with a demonstrated peak surface field exceeding 30MV/m at 7W rf cavity power. The solenoid produces fields up to 9T. In an initial beam test with a single module cavity performance exceeded design by over 20%. The full linac was installed by early 2006 with full linac beam commissioning tests starting in April 2006. The linac hardware will be described and the commissioning tests and results will be summarized.
|
|
|
||
| THP017 | Magnet Hysteresis Control at LANSCE | power-supply, quadrupole, linac, controls | 601 | ||
|
We have investigated the effects of magnet hysteresis in various beamlines at LANSCE (Los Alamos Neutron Science Center) and have developed procedures to control the effects. Particular challenges are presented by sets of magnets with parallel boosting and bucking windings on the same yoke powered by two families of supplies and by magnets whose fields are routinely reversed for different operating modes. The results of the procedures are more rapid recovery from power-off conditions and rapid switching between operating modes, with minimized re-tuning. The latter improvement has been beneficial in controlling a beam instability that has adverse effects on the users’ experiments.
|
|
|
||
| THP022 | Status of RF Sources in Super-Conducting RF Test Facility (STF) at KEK | klystron, superconducting-RF, controls, linac | 613 | ||
|
Super-conducting rf test facility (STF) has been progessing in KEK since 2005. In this paper, we describe the current status of rf sources in STF. STF rf sources comprise of a long pulse modulator with bouncer circuit, a pulse transformer, an L-band 5MW klystron, power distribution system and low level rf system. We have completed the construction of the first rf system and have been testing for the system evaluation and for the coupler test of the super-conducting cavity. We have a schedule to feed a power to the cryomodule with 8 super-conducting cavities in December of 2006. We also describe the plan of the second rf sources of STF.
|
|
|
||
| THP037 | Wide-Range Frequency Compensation by Coaxial Ball-Screw Tuner | resonance, linear-collider, booster, monitoring | 658 | ||
|
Low-loss 9-cell 1.3GHz cavities are studied at KEK aiming at a high-gradient operation for the International Linear Collider. One of the most important issues to realize such a high gradient in a pulsed operation of super-conducting cavities is the issue of how to compensate the Lorentz detuning. The Lorentz detuning of the cavity amounts to 3kHz at 45MV/m acceleration field. None of the tuners to date have achieved this range. A coaxial ball-screw tuner was designed and proved to reach this level in the room temperature operation. The performance at liquid Nitrogen temperature is also studied. From these results, we try to evaluate the feasibility of the operation at 2K.
|
|
|
||
| THP038 | Normal Conducting High-Gradient Studies at KEK | linear-collider, collider, extraction, vacuum | 661 | ||
|
Normal-conducting high field studies have been pursued at XTF, a high power X-band RF facility of KEK developed for linear collider. Three traveling-wave structures developed for X-band linear collider were studied in high field of more than 70MV/m level. High-field characteristic such as field emission properties and trip rate, etc. are studied carefully as the processing proceeds. Operation at 50MV/m level was found very stable while breakdowns happened once an hour or so at more than 70MV/m, indicating the approach to some critical point. This characteristics is discussed in conjunction with various author’s trials to make a scaling law of severe breakdowns among power, pulse width and so on. Further basic studies on field/power limitation or robustness against breakdowns in various materials are planned using narrowed waveguide configuration. Unique features related to this study is also described.
|
|
|
||
| THP049 | LANSCE DTL Longitudinal Field Measurements at High Power | insertion, resonance, linac, proton | 691 | ||
|
Shifts in proton beam tuning were observed in the DTL portion of the Los Alamos Neutron Science Center (LANSCE) Accelerator corresponding with cooling system obstructions during the 2003 operational cycle. A diagnostic system was developed to measure longitudinal field changes at the operational field levels to confirm the source of the tune shifts and track the effectiveness of cooling system repairs. This paper describes the diagnostic system and the results of field distribution measurements at high RF power in the accelerating structures.
|
|
|
||
| THP064 | Tuning a CW 4-Rod RFQ | rfq, resonance, pick-up, vacuum | 728 | ||
|
A 4-Rod RFQ has been built, which operates cw and will accelerate 5mA D beams up to 3 MeV. The length of the structure is 3.8 m, the power consumption as high as 250 kW. The tuning of a 4-Rod RFQ with 30 rf-cells at the frequency of 175 MHz is difficult, so procedures have been developed, to facilitate this work. The properties of the RFQ accelerator, the tuning procedure and the status of the project will be discussed.
|
|
|
||
| THP077 | A High-Gradient Test of a 30-GHz Copper Accelerating Structure | electron, linac, pick-up, vacuum | 761 | ||
|
The CLIC study is investigating a number of different materials at different frequencies in order to find ways to increase achievable accelerating gradient and to understand what are the important parameters for high-gradient operation. So far a series of rf tests have been made with a set of identical-geometry 30 GHz and X-band structures in copper, tungsten and molybdenum. A new test of a 30 GHz copper accelerating structure has been completed in CTF3 with pulse lengths up to 100 ns. The new results are presented and compared to the previous structures to determine dependencies of quantities such accelerating gradient, material, frequency, pulse length, power flow, conditioning rate, breakdown rate and surface damage.
|
|
|
||
| THP079 | High-Power Test of a 57-MHz CW RFQ | rfq, vacuum, pick-up, linac | 767 | ||
|
High power heavy-ion drivers require a CW low-frequency RFQ for initial acceleration. The technique of high-temperature furnace brazed OFE copper cavities has proven to be very reliable for the production of high-quality CW accelerating structures. By appropriate choice of the resonant structure for the RIA driver RFQ we have achieved moderate transverse dimensions of the cavity and high quality accelerating-focusing fields required for simultaneous acceleration of multiple charge state ion beams. In our application the RFQ must provide stable operation over a wide range of RF power levels. To demonstrate the technology and high-power operation we have built an engineering prototype of one-segment of the 57-MHz RFQ structure [1]. The RFQ is designed as a 100% OFE copper structure and fabricated with a two-step furnace brazing process. The brazing process was successful and the cavity was shown to be vacuum tight. The errors in the tip-to-tip distances of the vanes average less than 50 microns. The RF measurements show excellent electrical properties of the resonator with a measured unloaded Q equal to 95% of the simulated value. Currently high-power tests are being performed.
|
*J. W. Rathke et al., Preliminary Engineering Design of A 57.5 MHz CW RFQ for the RIA Driver LINAC. Proc. of the LINAC-2002, p. 467. |
|
||
| THP085 | Transportation of the DTL/SDTL for the J-PARC | alignment, target, linac, focusing | 782 | ||
|
Three DTL tanks and 32 SDTL tanks for the Japan Proton Accelerator Research Complex (J-PARC) were assembled at KEK site. After the assembling, the aging of the DTL1 and 12 SDTL tanks and the beam acceleration test for the DTL1 was done. And then all the DTL and SDTL tanks have to be transported form KEK to JAEA. The distance is about 95km and special air suspension trailer is used. To confirm the effect to the accuracy of the drift tube alignment, we measured the displacement of the drift tube positions before and after the transportation by using a hot model tank. As a result of the test, the displacement of the drift tubes by the transportation was less than 0.02mm which meets our requirements. Based on this result, all the DTL and SDTL tanks were transported form KEK to JAEA. In this paper, the transportation results of the hot model tank and the DTL/SDTL tanks are described.
|
|
|
||
| THP087 | Status of C-band Accelerating Section Development at the KEKB Injector Linac | linac, klystron, impedance, positron | 788 | ||
|
This paper reports on C-band accelerating section development for future energy upgrade of the KEKB injector linac. Target field gradient is 42 MV/m, that is twice of the present S-band sections in the linac. Until now, we have developed four 1m-long sections based on a half-scale design of the S-band section with improvements in coupler cavity shape and in fabrication method. And the fifth accelerating section is in fabrication now. The four sections have already installed in the beam line of the linac. Together with a unit of C-band rf source (50 MW klystron, pulse modulator, rf-pulse compressor) installed in the linac, we will perform an operation test of a model C-band accelerator module that has almost same configuration as a design module in the upgrade. Results of the long-term operation test and beam acceleration study will be described. And present status of development of the fifth accelerating section will also be given.
|
|
|