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Title: High current carbon beam production with direct plasma injection scheme

Abstract

We have been studying a new heavy-ion production technique called 'direct plasma injection scheme', DPIS, since 2000. A new radio frequency quadrupole (RFQ) designed especially for the DPIS was commissioned in 2004 and very intense carbon beam was successfully obtained, reaching more than 60 mA accelerated current from the RFQ. Most of the contents of the accelerated beam was carbon 4+ as verified by beam analysis.

Authors:
; ; ; ; ; ; ;  [1];  [2];  [2];  [2];  [2]
  1. RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
20779055
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2170045; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM PRODUCTION; CARBON; CURRENTS; HEAVY IONS; ION BEAMS; ION SOURCES; PLASMA; QUADRUPOLE LINACS

Citation Formats

Okamura, Masahiro, Kashiwagi, Hirotsugu, Sakakibara, Kazuhiko, Takano, Jumpei, Hattori, Toshiyuki, Hayashizaki, Noriyosu, Jameson, Robert A., Yamamoto, Kazuo, Japan Atomic Energy Agency, 1233 Watanuki cho, Takasaki-shi, Gunma 370-1292, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8550, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, and National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555. High current carbon beam production with direct plasma injection scheme. United States: N. p., 2006. Web. doi:10.1063/1.2170045.
Okamura, Masahiro, Kashiwagi, Hirotsugu, Sakakibara, Kazuhiko, Takano, Jumpei, Hattori, Toshiyuki, Hayashizaki, Noriyosu, Jameson, Robert A., Yamamoto, Kazuo, Japan Atomic Energy Agency, 1233 Watanuki cho, Takasaki-shi, Gunma 370-1292, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8550, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, & National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555. High current carbon beam production with direct plasma injection scheme. United States. doi:10.1063/1.2170045.
Okamura, Masahiro, Kashiwagi, Hirotsugu, Sakakibara, Kazuhiko, Takano, Jumpei, Hattori, Toshiyuki, Hayashizaki, Noriyosu, Jameson, Robert A., Yamamoto, Kazuo, Japan Atomic Energy Agency, 1233 Watanuki cho, Takasaki-shi, Gunma 370-1292, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8550, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, and National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555. Wed . "High current carbon beam production with direct plasma injection scheme". United States. doi:10.1063/1.2170045.
@article{osti_20779055,
title = {High current carbon beam production with direct plasma injection scheme},
author = {Okamura, Masahiro and Kashiwagi, Hirotsugu and Sakakibara, Kazuhiko and Takano, Jumpei and Hattori, Toshiyuki and Hayashizaki, Noriyosu and Jameson, Robert A. and Yamamoto, Kazuo and Japan Atomic Energy Agency, 1233 Watanuki cho, Takasaki-shi, Gunma 370-1292 and Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8550 and RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 and National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555},
abstractNote = {We have been studying a new heavy-ion production technique called 'direct plasma injection scheme', DPIS, since 2000. A new radio frequency quadrupole (RFQ) designed especially for the DPIS was commissioned in 2004 and very intense carbon beam was successfully obtained, reaching more than 60 mA accelerated current from the RFQ. Most of the contents of the accelerated beam was carbon 4+ as verified by beam analysis.},
doi = {10.1063/1.2170045},
journal = {Review of Scientific Instruments},
number = 3,
volume = 77,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ionmore » current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C{sup 6+} beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.« less
  • Acceleration of a 17 mA, 100 keV/u C{sup 6+} ion beam has been successfully achieved with an radio frequency quadrupole (RFQ) linac by means of 'direct injection scheme'. The C{sup 6+} beam produced by a laser ion source with a Nd:YAG laser was injected to the high current RFQ linac. It has been experimentally proved that the fully stripped carbon ion beam with a current more than 10 mA was accelerated by the RFQ linac.
  • In direct plasma injection scheme, the relation between the ion current from a laser ion source and the accelerated beam current by a radio-frequency quadrupole (RFQ) linac was studied by a series of the following analyses. First, ion current at beam extraction was calculated from measured plasma parameters using a scaling law. Second, the beam emittance at the entrance of acceleration electrode region was evaluated by the simulation of the ion extraction out of the ion source plasma using the result of the first calculation. Last, the accelerated beam current could be reproduced by the simulation of beam acceleration usingmore » the results of the second. The second calculation revealed the time variation in the injected beam parameter to the RFQ linac. Then it was proved that the time structure of the accelerated beam was different from that of the injection beam because the degree of the matching between the injected beam emittance and the RFQ acceptance varied with time.« less
  • Direct plasma injection scheme (DPIS) is a recently developed idea about beam injection into a radio frequency quadrupole (RFQ) linac to obtain high current pulsed heavy ion beam. Since a laser ion source is directly connected to an RFQ linac, a low energy beam transport is not needed. An ion beam is extracted at the edge of the cavity. We shifted the extraction position in the RFQ cavity to improve the beam loss problem due to beam diverging before arriving at the entrance of the RFQ electrode region. In this scheme, ion beam is extracted at the entrance of themore » RFQ electrode region and the extracted beam is immediately captured by a rf quadrupole electric field. A plasma electrode is inserted in the accelerator resonant cavity. It is required to avoid serious effect on the acceleration characteristics of the RFQ linac. The rf properties were measured using a network analyzer to verify the effect. The shifts of resonant frequency were negligibly small by inserting the electrode. The measurements of the electric field distribution along the beam axis in the RFQ linac showed that the plasma electrode had little effect on it. The result of beam acceleration experiment showed that the beam current was increased by about 20%. It was confirmed that the beam loss was reduced by this scheme.« less
  • We developed a laser ion source using a direct plasma injection scheme (DPIS) as an injection system for a two-beam type radio frequency quadrupole (RFQ) linac with an interdigital-H (IH) type cavity. The laser ion source in the DPIS is directly connected to the RFQ cavity without the low energy beam transport system. We achieved a high current C{sup 2+} beam above 60 mA per beam channel from the ion source. The beam will be injected to the two-beam type IH-RFQ linac, and the linac will generate a beam current of approximately 44 mA per beam channel.