| Paper |
Title |
Page |
| TUPLS104 |
Matching of High Intensity Ion Beams to an RFQ: Comparison of PARMTEQ and IGUN Simulations
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1741 |
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- R. Becker, R.A. Jameson
IAP, Frankfurt-am-Main
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The classical way of matching an ion source to the low energy accelerator RFQ generally is performed by adjusting the matching optics of the LEBT to provide the rms ellipse twiss parameter requirements of the RFQ shaper section. By matching to the rms parameters (the equivalent rms beam method) the actual shape of the distribution plays a smaller role according to F. Sacherer. In many cases, however, the matching optics are creating not only aberrations to the ion beam but also a very non-elliptical shape of the emittance figure, and a more exact match may be required. As a way out, an ion extraction program (IGUN) has been modified to also take into account the rf-focusing of non-modulated RFQ vanes in the shaper section. This makes it feasible to use this program for the simulation from the ion source plasma until the beginning of modulation inside the RFQ, and it can also handle dc fields in the injection region of the RFQ. In order to demonstrate the differences of both approaches we apply them to well defined experimentally proved designs of RFQ shaper sections.
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| THPCH015 |
Matched and Equipartitioned Method for High-intensity RFQ Accelerators
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2814 |
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- X.Q. Yan, J.-E. Chen, J.X. Fang, Z.Y. Guo, Y.R. Lu
PKU/IHIP, Beijing
- R.A. Jameson
LANL, Los Alamos, New Mexico
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Maintaining beam envelope match, avoiding structure resonances, and using an equilibrium (equipartitioned) energy balance within the beam are the primary methods for preventing emittance growth and halo formation in high current linacs. A design strategy that requires the RFQ accelerator to be matched and equipartitioned over most of its length will produces very robust designs under a wide variety of conditions, the beam with proper energy balance is also inherently stable against resonances near the operation point. Based on this strategy, a new dynamics method is proposed to avoid the envelope mismatch and energy imbalance between different degrees of freedom. The beam sizes are well confined to match the accelerating channel in this method, to minimize the emittance growth and the related beam loss. Following the method, a RFQ design code named MATCHDESIGN has been written at Peking University. A test design of 50mA proton RFQ operating at 350 MHz was given to prove this method and it resulted in a good dynamics design.
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| TUPLS095 |
Recent Progress about DPIS
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0 |
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- M. Okamura, R.A. Jameson
RIKEN, Saitama
- T. Kanesue
Kyushu University, Hakozaki
- H. Kashiwagi
JAEA/ARTC, Gunma-ken
- A. Kondrashev
ITEP, Moscow
- K. Sakakibara
RLNR, Tokyo
- A. Schempp
IAP, Frankfurt-am-Main
- J. Tamura
TIT, Yokohama
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We have focused on high brightness of induced plasma in Laser Ion Source (LIS) to provide intense highly charged ions efficiently. To take the advantage of the intrinsic density of the laser plasma, Direct Plasma Injection Scheme (DPIS) has been developed. The induced laser plasma has initial expanding velocity and can be delivered directly to the RFQ. Extraction electrodes and focusing devices in LEBT are not needed. Since 2004, a newly designed RFQ has been used to verify the capability of the new ion production scheme. We succeeded to accelerate 60 m A of Carbon beam and 60 mA of Aluminium beam. We have also tried to understand plasma properties of various species by measuring charge states distributions and time structures, and are now ready to accelerate heavier species. Currently Silver 15+ beam is planned to be accelerated. In the conference, design strategies and detailed techniques for the DPIS will be described based on the measured plasma properties of various elements and new findings obtained from recent acceleration experiments. The durability and the reproducibility will be also explained.
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