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Title: Acceleration of 500 keV Negative Ion Beams By Tuning Vacuum Insulation Distance On JT-60 Negative Ion Source

Abstract

Acceleration of a 500 keV beam up to 2.8 A has been achieved on a JT-60U negative ion source with a three-stage accelerator by overcoming low voltage holding which is one of the critical issues for realization of the JT-60SA ion source. In order to improve the voltage holding, preliminary voltage holding tests with small-size grids with uniform and locally intense electric fields were carried out, and suggested that the voltage holding was degraded by both the size and local electric field effects. Therefore, the local electric field was reduced by tuning gap lengths between the large size grids and grid support structures of the accelerator. Moreover, a beam radiation shield which limited extension of the minimum gap length was also optimized so as to reduce the local electric field while maintaining the shielding effect. These modifications were based on the experiment results, and significantly increased the voltage holding from <150 kV/stage for the original configuration to 200 kV/stage. These techniques for improvement of voltage holding should also be applicable to other large ion sources accelerators such as those for ITER.

Authors:
; ; ; ; ; ; ; ;  [1]; ;  [2];  [3]
  1. Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193 (Japan)
  2. Saitama University, Saitama, Saitama-ken, 338-8570 (Japan)
  3. Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States)
Publication Date:
OSTI Identifier:
21611692
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1390; Journal Issue: 1; Conference: 2. international symposium on negative ions, beams and sources, Takayama City (Japan), 16-19 Nov 2010; Other Information: DOI: 10.1063/1.3637418; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATORS; ANIONS; ELECTRIC FIELDS; ELECTRIC POTENTIAL; ION BEAMS; ION SOURCES; ITER TOKAMAK; JT-60 TOKAMAK; JT-60U TOKAMAK; KEV RANGE; BEAMS; CHARGED PARTICLES; CLOSED PLASMA DEVICES; ENERGY RANGE; IONS; THERMONUCLEAR DEVICES; THERMONUCLEAR REACTORS; TOKAMAK DEVICES; TOKAMAK TYPE REACTORS

Citation Formats

Kojima, A., Hanada, M., Tanaka, Y., Taniguchi, M., Kashiwagi, M., Inoue, T., Umeda, N., Watanabe, K., Tobari, H., Kobayashi, S., Yamano, Y., and Grisham, L. R. Acceleration of 500 keV Negative Ion Beams By Tuning Vacuum Insulation Distance On JT-60 Negative Ion Source. United States: N. p., 2011. Web. doi:10.1063/1.3637418.
Kojima, A., Hanada, M., Tanaka, Y., Taniguchi, M., Kashiwagi, M., Inoue, T., Umeda, N., Watanabe, K., Tobari, H., Kobayashi, S., Yamano, Y., & Grisham, L. R. Acceleration of 500 keV Negative Ion Beams By Tuning Vacuum Insulation Distance On JT-60 Negative Ion Source. United States. doi:10.1063/1.3637418.
Kojima, A., Hanada, M., Tanaka, Y., Taniguchi, M., Kashiwagi, M., Inoue, T., Umeda, N., Watanabe, K., Tobari, H., Kobayashi, S., Yamano, Y., and Grisham, L. R. Mon . "Acceleration of 500 keV Negative Ion Beams By Tuning Vacuum Insulation Distance On JT-60 Negative Ion Source". United States. doi:10.1063/1.3637418.
@article{osti_21611692,
title = {Acceleration of 500 keV Negative Ion Beams By Tuning Vacuum Insulation Distance On JT-60 Negative Ion Source},
author = {Kojima, A. and Hanada, M. and Tanaka, Y. and Taniguchi, M. and Kashiwagi, M. and Inoue, T. and Umeda, N. and Watanabe, K. and Tobari, H. and Kobayashi, S. and Yamano, Y. and Grisham, L. R.},
abstractNote = {Acceleration of a 500 keV beam up to 2.8 A has been achieved on a JT-60U negative ion source with a three-stage accelerator by overcoming low voltage holding which is one of the critical issues for realization of the JT-60SA ion source. In order to improve the voltage holding, preliminary voltage holding tests with small-size grids with uniform and locally intense electric fields were carried out, and suggested that the voltage holding was degraded by both the size and local electric field effects. Therefore, the local electric field was reduced by tuning gap lengths between the large size grids and grid support structures of the accelerator. Moreover, a beam radiation shield which limited extension of the minimum gap length was also optimized so as to reduce the local electric field while maintaining the shielding effect. These modifications were based on the experiment results, and significantly increased the voltage holding from <150 kV/stage for the original configuration to 200 kV/stage. These techniques for improvement of voltage holding should also be applicable to other large ion sources accelerators such as those for ITER.},
doi = {10.1063/1.3637418},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1390,
place = {United States},
year = {Mon Sep 26 00:00:00 EDT 2011},
month = {Mon Sep 26 00:00:00 EDT 2011}
}