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| MO1003 | Commissioning of the J-PARC Linac | linac, rfq, klystron, ion-source | 6 | ||
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rt in December, 2006. All the components have been installed in the linac tunnel and the klystron gallery, respectively. The preparation for the beam commissioning is under way as scheduled, except for the air-pressure control system, which delayed the powering of the cavities by one month. If no more serious trouble, the beam commissioning will start on schedule. The J-PARC linac comprises the 3-MeV, 324-MHz RFQ linac, the 50-MeV DTL, and the 181-MeV SDTL and the 400-MeV, 972-MHz ACS. It is unique by making use of many newly developed or invented accelerator technologies.
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| MOP005 | Beam Dynamics for Intense L-band Electron Linac | electron, linac, bunching, simulation | 37 | ||
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We are now developing an intense L-band electron linac with a traveling-wave accelerating structure for irradiation applications. It is capable to produce 10 MeV electron beams of 30 kW by a pulsed klystron of 25 MW with a 60 kW average power. Bunching and accelerating cavities operated with 2π/3 mode at 1.3 GHz are designed by the SUPERFISH code. Focusing solenoids are designed by the POISSON code. Using electromagnetic field configurations obtained by these codes, a simulational study on the beam dynamics is conducted by the PARMELA code. As results, the beam envelope supports a transmission efficiency over 91% with the E-gun current of 1.6 A.
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| MOP017 | 4GLS Beam-Break-Up Investigations | linac, recirculation, simulation, quadrupole | 67 | ||
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Beam Break Up (BBU) thresholds have been studied as part of the Linac focusing scheme for the proposed 4GLS accelerator. A graded gradient focusing scheme, with a triplet of quadrupoles between each of the modules within the Linac has been chosen. These quadrupoles are set-up in a defocusing – focusing – defocusing format with strengths of -1/2k, k, -1/2k. This value of k was altered and the BBU thresholds for the machine calculated using various BBU codes. Alternate cavity designs have also been investigated using CST’s Microwave Studio to see how the effects of higher order modes (HOMs) can be minimised whilst maintaining fundamental field flatness across theaccelerating cells. The number of cells/unit length and cell-to-cell geometries have also been parameterised and the corresponding BBU thresholds presented as a function of cavity geometry, with the intention of providing an optimum solution for 4GLS.
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| MOP045 | Performance of SNS Front End and Warm Linac | linac, beam-losses, SNS, emittance | 145 | ||
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The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. With the completion of beam commissioning, the accelerator complex began operation in June 2006. Injector and warm linac performance results will be presented including transverse emittance evolution along the linac, longitudinal bunch profile measurements at the beginning and end of the linac, and the results of a beam loss study.
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| TUP046 | Experimental Studies of Electrostatic and Solenoidal Focusing of Low-Energy, Heavy-Ion ECRIS Beams at the NSCL/MSU | emittance, dipole, ion, injection | 352 | ||
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Replacement of the focusing solenoids between both ECR Ion Sources and the beam analysis dipoles with electrostatic triplets has resulted in a large increase in net accelerator output. 2D emittance scans explain some but not all of this increase. Further improvement is anticipated with a new optical device consisting of an electrostatic quadrupole doublet-octupole-doublet-magnetic sextupole arrangement, which has been built and is being tested in place of a triplet. Motivations and results of measurements and operating experience are discussed.
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| TUP048 | Beam-Loading Effect in the Normal-Conducting ILC Positron Source Pre-Accelerator | positron, beam-loading, linac, linear-collider | 355 | ||
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Significant positron bunch charge (several nC) in the ILC Positron Source results in high pulse beam loading for normal-conducting accelerating structures in Positron Pre-Accelerator (PPA). Time interval between bunches (~ 300 ns) is not negligibly small in comparison with accelerating structure time constant (rise time for Standing Wave (SW) or filling time for Traveling Wave (TW) options). As the result, beam loading effect has particularities both from stored energy acceleration regime and continuous beam loading one. Taking into account particular PPA beam structure, beam loading effect is estimated for the present ILC base line parameters, both for SW and TW PPA options. Possible solutions for beam loading compensation are discussed.
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| TUP069 | Design of 132MeV DTL for CSNS | SNS, simulation, linac, vacuum | 412 | ||
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A description is given to the drift-tube-linac (DTL) of the Beijing Spallation Neutron Source (BSNS). The DTL accelerate a 3MeV, 30mA H- beam from the RFQ to the LRBT. Tank body and drift tube configuration design using the SUPERFISH code has enabled efficient optimization of the effective shunt impedance and avoided high surface field. Accelerating cells design and particle tracking were made by using PARMILA code. Special emphasis is given to the transverse focusing system design, which was compared with two usual schemes, constant phase focusing and equipartitioning focusing. Details of beam dynamics analysis will be presented in this paper.
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| TUP072 | Beam Dynamics Studies of the 8-GeV Superconducting H- Linac | linac, simulation, beam-losses, rfq | 420 | ||
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A 8-GeV H-minus linac has been proposed to enhance the accelerator complex at Fermilab as a high-intensity neutrino source.* The linac is based on 430 independently phased superconducting cavities. The front-end of the linac (up to 420 MeV) operating at 325 MHz is based on RIA-type multi-spoke cavities. The rest of the linac (from 420 MeV to 8 GeV) uses ILC-type elliptical cavities. We have performed large scale end-to-end beam dynamics simulations of the driver linac using the code TRACK** including all sources of machine errors and detailed beam loss analysis. The results of these simulations will be presented and discussed.
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* G. W. Foster and J. A. MacLachlan, Proceedings of LINAC-2002, p.826. |
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| TUP075 | Automatic Transverse and Longitudinal Tuning of Single and Multiple Charge State Ion Beams | linac, beam-losses, emittance, simulation | 429 | ||
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Extensive end-to-end beam dynamics simulations of the RIA driver linac using the code TRACK and including all sources of machine errors and detailed beam loss analysis* showed that the losses could be significantly reduced for a fine-tuned linac. For this purpose we have developed an automatic longitudinal tuning proceedure for multiple charge state heavy-ion beams.** For a complete tuning tool, we have recently developed an automatic transverse tuning proceedure to produce smooth transverse beam dynamics by minimizing the RMS beam sizes after each focusing period. We have also extended the automatic longitudinal proceedure to produce smooth longitudinal beam dynamics for single and multiple charge state ion beams. In addition to improving an existing tune, this powerful automatic beam tuning tool can be used to retune the linac and restore the beam after one or more elements failures and to develop new tunes for ion beams with different Q/A ratios. After presenting the method, the results from some applications will be presented and discussed.
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* P. Ostroumov, V. Assev and B. Mustapha, Phys. Rev. ST-AB 7 (2004) 090101 |
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| TUP076 | First TRACK Simulations of the SNS Linac | linac, simulation, SNS, lattice | 432 | ||
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In an effort to benchmark the code TRACK* against the recent commissionnig data from the SNS linac, we started updating the code TRACK to support SNS-type elements like DTL's and CCL's. 2D electric field tables were computed using SUPERFISH and 3D magnetic fields from PMQ's were calculated using EMS-Studio. A special DTL routine was implemented and successfully tested. The first results of TRACK simulations using a realistic beam will be presented. A comparison with the code PARMILA will also be presented and discussed.
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* "TRACK: The New Beam Dynamics code", V. N. Aseev et al, in Proceedings |
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| TUP077 | Transverse Beam Matching and Correction Procedures in INR Linac | linac, quadrupole, controls, simulation | 435 | ||
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An interactive procedure for the transverse beam matching and correction has been developed and implemented in several areas of INR Linac. The profile measurements are used for determination of the main transverse beam parameters. These data are applied for calculation the dipole correction currents and quadrupole gradients to transport the beam with minimum sizes and off axis displacements. The user friendly interface and graphics support has been developed for data treatment and beam behavior presentation. The proposed algorithm of beam matching, beam steering and data treatment is discussed. Some experimental and simulation results for different INR Linac operation modes are presented.
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| TUP081 | Impact of a RF Frequency Change on the Longitudinal Beam Dynamics | linac, emittance, acceleration, ion | 447 | ||
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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.
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| THP057 | Design of Normal Conducting 325-MHz Crossbar H-Type Resonators at Femirlab | linac, lattice, vacuum, impedance | 710 | ||
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The warm section of the proposed High Intensity Neutrino Source at Fermilab is designed to accelerate H- ions and protons from 2.5 MeV to 10 MeV (β=0.0744 to β=0.1422). After the ion source, the beam will travel through a radio frequency quadrupole, a medium energy beam transport (two buncher cavities and a chopper) and finally 16 normal-conducting resonators, all separated by superconducting solenoids in individual cryostats. Over 10 MeV the design uses superconducting resonators and solenoids in common cryomodules. In this paper the electromagnetic design and optimization of all the 325 MHz Crossbar H-type normal-conducting resonators is presented. The mechanical design, performance and fabrication of the first prototype (β=0.0744) is presented in detail. The design of the prototype for the input coupler that will be used in the resonators is included.
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| THP085 | Transportation of the DTL/SDTL for the J-PARC | acceleration, alignment, target, linac | 782 | ||
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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.
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