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Title: Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

Abstract

R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated asmore » 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Japan Atomic Energy Agency, 801-1 Mukouyama, Naka-shi, Ibaraki 311-0193 Japan (Japan)
Publication Date:
OSTI Identifier:
22391438
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1655; Journal Issue: 1; Conference: NIBS 2014: 4. International Symposium on Negative Ions, Beams and Sources, Garching (Germany), 6-10 Oct 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATION; ACCELERATORS; BEAM CURRENTS; BEAM INJECTION HEATING; CATIONS; ELECTROMAGNETIC PULSES; ELECTRON EMISSION; ENERGY DENSITY; HEATING LOAD; HYDROGEN IONS 1 MINUS; ION BEAMS; ITER TOKAMAK; JAEA; KEV RANGE; MEV RANGE; NEUTRAL ATOM BEAM INJECTION; POWER DENSITY; TEST FACILITIES

Citation Formats

Umeda, N., E-mail: umeda.naotaka@jaea.go.jp, Kojima, A., Kashiwagi, M., Tobari, H., Hiratsuka, J., Watanabe, K., Dairaku, M., Yamanaka, H., and Hanada, M. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER. United States: N. p., 2015. Web. doi:10.1063/1.4916458.
Umeda, N., E-mail: umeda.naotaka@jaea.go.jp, Kojima, A., Kashiwagi, M., Tobari, H., Hiratsuka, J., Watanabe, K., Dairaku, M., Yamanaka, H., & Hanada, M. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER. United States. https://doi.org/10.1063/1.4916458
Umeda, N., E-mail: umeda.naotaka@jaea.go.jp, Kojima, A., Kashiwagi, M., Tobari, H., Hiratsuka, J., Watanabe, K., Dairaku, M., Yamanaka, H., and Hanada, M. 2015. "Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER". United States. https://doi.org/10.1063/1.4916458.
@article{osti_22391438,
title = {Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER},
author = {Umeda, N., E-mail: umeda.naotaka@jaea.go.jp and Kojima, A. and Kashiwagi, M. and Tobari, H. and Hiratsuka, J. and Watanabe, K. and Dairaku, M. and Yamanaka, H. and Hanada, M.},
abstractNote = {R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.},
doi = {10.1063/1.4916458},
url = {https://www.osti.gov/biblio/22391438}, journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1655,
place = {United States},
year = {Wed Apr 08 00:00:00 EDT 2015},
month = {Wed Apr 08 00:00:00 EDT 2015}
}