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Title: Improvement of JT-60U Negative Ion Source Performance

Abstract

The negative ion neutral beam system now operating on JT-60U was the first application of negative ion technology to the production of beams of high current and power for conversion to neutral beams, and has successfully demonstrated the feasibility of negative ion beam heating systems for ITER and future tokamak reactors [1, 2]. It also demonstrated significant electron heating[3] and high current drive efficiency in JT-60U[4]. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. We have explored the physical mechanisms responsible for these processes, and implemented solutions for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and nonuniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roug hly a third, and permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density, and in coping with the sensitivity of the cesium in the ion sources to oxidation by tiny air or water leaks, and themore » cathode operation is being altered.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Princeton Plasma Physics Lab., Princeton, NJ (US)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
768650
Report Number(s):
PPPL-3507
TRN: US0005775
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Conference
Resource Relation:
Conference: 18th International Atomic Energy Agency's (IAEA) Fusion Energy Conference (FEC-2000), Sorrento (IT), 10/04/2000--10/10/2000; Other Information: PBD: 15 Nov 2000
Country of Publication:
United States
Language:
English
Subject:
29 ENERGY PLANNING, POLICY AND ECONOMY; BEAM EXTRACTION; BEAM INJECTION; CURRENT DENSITY; IAEA; ION SOURCES; NUCLEAR ENERGY; PERFORMANCE; THERMONUCLEAR REACTORS

Citation Formats

L.R. Grisham, M. Kuriyama, M. Kawai, T. Itoh, N. Umeda, and JT-60U Team. Improvement of JT-60U Negative Ion Source Performance. United States: N. p., 2000. Web.
L.R. Grisham, M. Kuriyama, M. Kawai, T. Itoh, N. Umeda, & JT-60U Team. Improvement of JT-60U Negative Ion Source Performance. United States.
L.R. Grisham, M. Kuriyama, M. Kawai, T. Itoh, N. Umeda, and JT-60U Team. Wed . "Improvement of JT-60U Negative Ion Source Performance". United States. https://www.osti.gov/servlets/purl/768650.
@article{osti_768650,
title = {Improvement of JT-60U Negative Ion Source Performance},
author = {L.R. Grisham and M. Kuriyama and M. Kawai and T. Itoh and N. Umeda and JT-60U Team},
abstractNote = {The negative ion neutral beam system now operating on JT-60U was the first application of negative ion technology to the production of beams of high current and power for conversion to neutral beams, and has successfully demonstrated the feasibility of negative ion beam heating systems for ITER and future tokamak reactors [1, 2]. It also demonstrated significant electron heating[3] and high current drive efficiency in JT-60U[4]. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. We have explored the physical mechanisms responsible for these processes, and implemented solutions for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and nonuniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roug hly a third, and permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density, and in coping with the sensitivity of the cesium in the ion sources to oxidation by tiny air or water leaks, and the cathode operation is being altered.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Nov 15 00:00:00 EST 2000},
month = {Wed Nov 15 00:00:00 EST 2000}
}

Conference:
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