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Title: Ion beam reflection in a 180/sup 0/ bending magnet system

Abstract

Several kinds of bending magnet systems are used in present neutral beam injectors. In these systems the fringe magnetic field due to finite dimensions of the bending magnet plays an important role in the ion beam deflection. The power deposition profile on the ion dump surface is strongly influenced by the exit angles of the reflected ions with respect to the magnet boundary. However, it is not easy to predict the exit angles of the ions because both focusing and defocusing forces act on these ions during their reflections, and hence it is difficult to predict whether the power density on the ion dump surface increases or decreases. In order to investigate the effect of the fringe magnetic field on beam reflection in a 180/sup 0/ bending magnet system, we calculate power deposition profiles on the ion dump surface by applying a Monte Carlo technique. The computational results show that the power deposition profile is very sensitive to change of the magnetic field strength. When the magnetic field strength increases by 5%, for example, the maximum power density shows an increase of 80%. We also compare the calculated power deposition profile with the experimentally measured profile. The measured profiles aremore » in good agreement with the calculated ones without considering the beam expansion due to a space-charge effect of the reflecting ions.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Institute of Plasma Physics, Nagoya University, Nagoya 464-01, Japan
OSTI Identifier:
6793196
Alternate Identifier(s):
OSTI ID: 6793196
Resource Type:
Journal Article
Journal Name:
Rev. Sci. Instrum.; (United States)
Additional Journal Information:
Journal Volume: 59:10
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BEAM BENDING MAGNETS; BEAM OPTICS; DESIGN; ION BEAMS; NEUTRAL BEAM SOURCES; REFLECTION; BEAMS; ELECTRICAL EQUIPMENT; ELECTROMAGNETS; EQUIPMENT; MAGNETS 700202* -- Fusion Power Plant Technology-- Magnet Coils & Fields; 700205 -- Fusion Power Plant Technology-- Fuel, Heating, & Injection Systems

Citation Formats

Sakurai, K., Oka, Y., Kaneko, O., and Kuroda, T. Ion beam reflection in a 180/sup 0/ bending magnet system. United States: N. p., 1988. Web. doi:10.1063/1.1139980.
Sakurai, K., Oka, Y., Kaneko, O., & Kuroda, T. Ion beam reflection in a 180/sup 0/ bending magnet system. United States. doi:10.1063/1.1139980.
Sakurai, K., Oka, Y., Kaneko, O., and Kuroda, T. Sat . "Ion beam reflection in a 180/sup 0/ bending magnet system". United States. doi:10.1063/1.1139980.
@article{osti_6793196,
title = {Ion beam reflection in a 180/sup 0/ bending magnet system},
author = {Sakurai, K. and Oka, Y. and Kaneko, O. and Kuroda, T.},
abstractNote = {Several kinds of bending magnet systems are used in present neutral beam injectors. In these systems the fringe magnetic field due to finite dimensions of the bending magnet plays an important role in the ion beam deflection. The power deposition profile on the ion dump surface is strongly influenced by the exit angles of the reflected ions with respect to the magnet boundary. However, it is not easy to predict the exit angles of the ions because both focusing and defocusing forces act on these ions during their reflections, and hence it is difficult to predict whether the power density on the ion dump surface increases or decreases. In order to investigate the effect of the fringe magnetic field on beam reflection in a 180/sup 0/ bending magnet system, we calculate power deposition profiles on the ion dump surface by applying a Monte Carlo technique. The computational results show that the power deposition profile is very sensitive to change of the magnetic field strength. When the magnetic field strength increases by 5%, for example, the maximum power density shows an increase of 80%. We also compare the calculated power deposition profile with the experimentally measured profile. The measured profiles are in good agreement with the calculated ones without considering the beam expansion due to a space-charge effect of the reflecting ions.},
doi = {10.1063/1.1139980},
journal = {Rev. Sci. Instrum.; (United States)},
number = ,
volume = 59:10,
place = {United States},
year = {1988},
month = {10}
}