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Title: Measurements of Beam Ion Loss from the Compact Helical System

Abstract

Beam ion loss from the Compact Helical System (CHS) has been measured with a scintillator-type probe. The total loss to the probe, and the pitch angle and gyroradius distributions of that loss, have been measured as various plasma parameters were scanned. Three classes of beam ion loss were observed at the probe position: passing ions with pitch angles within 10o of those of transition orbits, ions on transition orbits, and ions on trapped orbits, typically 15o or more from transition orbits. Some orbit calculations in this geometry have been performed in order to understand the characteristics of the loss. Simulation of the detector signal based upon the following of orbits from realistic beam deposition profiles is not able to reproduce the pitch angle distribution of the losses measured. Consequently it is inferred that internal plasma processes, whether magnetohydrodynamic modes, radial electric fields, or plasma turbulence, move previously confined beam ions to transition orbits, resulting in their loss.

Authors:
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
973204
Report Number(s):
PPPL-4500
TRN: US1001908
DOE Contract Number:  
DE-ACO2-09CH11466
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DEPOSITION; DISTRIBUTION; ELECTRIC FIELDS; GEOMETRY; INCLINATION; MAGNETOHYDRODYNAMICS; PLASMA; PROBES; SIMULATION; TURBULENCE; Helical Devices, Stellarators CHS, Neutral Beams

Citation Formats

D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan. Measurements of Beam Ion Loss from the Compact Helical System. United States: N. p., 2010. Web. doi:10.2172/973204.
D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan. Measurements of Beam Ion Loss from the Compact Helical System. United States. doi:10.2172/973204.
D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan. Wed . "Measurements of Beam Ion Loss from the Compact Helical System". United States. doi:10.2172/973204. https://www.osti.gov/servlets/purl/973204.
@article{osti_973204,
title = {Measurements of Beam Ion Loss from the Compact Helical System},
author = {D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan},
abstractNote = {Beam ion loss from the Compact Helical System (CHS) has been measured with a scintillator-type probe. The total loss to the probe, and the pitch angle and gyroradius distributions of that loss, have been measured as various plasma parameters were scanned. Three classes of beam ion loss were observed at the probe position: passing ions with pitch angles within 10o of those of transition orbits, ions on transition orbits, and ions on trapped orbits, typically 15o or more from transition orbits. Some orbit calculations in this geometry have been performed in order to understand the characteristics of the loss. Simulation of the detector signal based upon the following of orbits from realistic beam deposition profiles is not able to reproduce the pitch angle distribution of the losses measured. Consequently it is inferred that internal plasma processes, whether magnetohydrodynamic modes, radial electric fields, or plasma turbulence, move previously confined beam ions to transition orbits, resulting in their loss.},
doi = {10.2172/973204},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {2}
}