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Title: Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX

Abstract

Experiments have been performed in the National Spherical Torus Experiment (NSTX) to inject high harmonic fast wave (HHFW) power early during the plasma current ramp-up in an attempt to reduce the current penetration rate to raise the central safety factor during the flattop phase of the discharge. To date, up to 2 MW of HHFW power has been coupled to deuterium plasmas as early as t = 50 ms using the slowest interstrap phasing of k|| approximately equals 14 m(superscript)-1 (nf = 24). Antenna-plasma gap scans have been performed and find that for small gaps (5-8 cm), electron heating is observed with relatively small density rises and modest reductions in current penetration rate. For somewhat larger gaps (10-12 cm), weak electron heating is observed but with a spontaneous density rise at the plasma edge similar to that observed in NSTX H-modes. In the larger gap configuration, EFIT code reconstructions (without MSE [motional Stark effect]) find that resistive flux consumption is reduced as much as 30%, the internal inductance is maintained below 0.6 at 1 MA into the flattop, q(0) is increased significantly, and the MHD stability character of the discharges is strongly modified.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Princeton Plasma Physics Lab., NJ (US)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
784550
Report Number(s):
PPPL-3564
TRN: US0106115
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 18 May 2001
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; NSTX DEVICE; BEAM INJECTION; SAFETY ENGINEERING; DEUTERIUM; ELECTRONS; HEATING; INDUCTANCE; PLASMA DENSITY; MAGNETOHYDRODYNAMICS

Citation Formats

Mendard, J.E., LeBlanc, Wilson, J.R., Sabbagh, S.A., Stutman, D., and and Swain, D.W.. Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX. United States: N. p., 2001. Web. doi:10.2172/784550.
Mendard, J.E., LeBlanc, Wilson, J.R., Sabbagh, S.A., Stutman, D., & and Swain, D.W.. Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX. United States. doi:10.2172/784550.
Mendard, J.E., LeBlanc, Wilson, J.R., Sabbagh, S.A., Stutman, D., and and Swain, D.W.. Fri . "Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX". United States. doi:10.2172/784550. https://www.osti.gov/servlets/purl/784550.
@article{osti_784550,
title = {Profile Modifications Resulting from Early High-harmonic Fast Wave heating in NSTX},
author = {Mendard, J.E. and LeBlanc, Wilson, J.R. and Sabbagh, S.A. and Stutman, D. and and Swain, D.W.},
abstractNote = {Experiments have been performed in the National Spherical Torus Experiment (NSTX) to inject high harmonic fast wave (HHFW) power early during the plasma current ramp-up in an attempt to reduce the current penetration rate to raise the central safety factor during the flattop phase of the discharge. To date, up to 2 MW of HHFW power has been coupled to deuterium plasmas as early as t = 50 ms using the slowest interstrap phasing of k|| approximately equals 14 m(superscript)-1 (nf = 24). Antenna-plasma gap scans have been performed and find that for small gaps (5-8 cm), electron heating is observed with relatively small density rises and modest reductions in current penetration rate. For somewhat larger gaps (10-12 cm), weak electron heating is observed but with a spontaneous density rise at the plasma edge similar to that observed in NSTX H-modes. In the larger gap configuration, EFIT code reconstructions (without MSE [motional Stark effect]) find that resistive flux consumption is reduced as much as 30%, the internal inductance is maintained below 0.6 at 1 MA into the flattop, q(0) is increased significantly, and the MHD stability character of the discharges is strongly modified.},
doi = {10.2172/784550},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri May 18 00:00:00 EDT 2001},
month = {Fri May 18 00:00:00 EDT 2001}
}

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