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Development of NSTX Particle Control Techniques.

DE2004828583

Publication Date	2004
Personal Author	Kugel, H. W.; Maingi, R.; Bell, M.
Page Count	22
Abstract	The National Spherical Torus Experiment (NSTX) High Harmonic Fast Wave (HHFW) current-drive discharges will require density control for acceptable efficiency. In NSTX, this involves primarily controlling impurity influxes and recycling. We have compared boronization on hot and cold surfaces, varying helium glow discharge conditioning (HeGDC) durations, helium discharge cleaning, brief daily boronization, and between discharge boronization to reduce and control spontaneous density rises. Access to Ohmic H-modes was enabled by boronization on hot surfaces, however, the duration of the effectiveness of hot and cold boronization was comparable. A 15 minute HeGDC between discharges was needed for reproducible L-H transitions. Helium discharge conditioning yielded slower density rises than 15 minutes of HeGDC.
Keywords	Tokamak devices Particles Plasma confinement Cleaning Efficiency Electric currents Glow discharges Harmonics Helium Performance Recycling National Spherical Torus Experiment(NSTX)
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Princeton Univ., NJ. Plasma Physics Lab.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200513

Development of NSTX Particle Control Techniques.

Development of NSTX Particle Control Techniques.
DE2004828583

Publication Date	2004
Personal Author	Kugel, H. W.; Maingi, R.; Bell, M.
Page Count	22
Abstract	The National Spherical Torus Experiment (NSTX) High Harmonic Fast Wave (HHFW) current-drive discharges will require density control for acceptable efficiency. In NSTX, this involves primarily controlling impurity influxes and recycling. We have compared boronization on hot and cold surfaces, varying helium glow discharge conditioning (HeGDC) durations, helium discharge cleaning, brief daily boronization, and between discharge boronization to reduce and control spontaneous density rises. Access to Ohmic H-modes was enabled by boronization on hot surfaces, however, the duration of the effectiveness of hot and cold boronization was comparable. A 15 minute HeGDC between discharges was needed for reproducible L-H transitions. Helium discharge conditioning yielded slower density rises than 15 minutes of HeGDC.
Keywords	Tokamak devices Particles Plasma confinement Cleaning Efficiency Electric currents Glow discharges Harmonics Helium Performance Recycling National Spherical Torus Experiment(NSTX)
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Princeton Univ., NJ. Plasma Physics Lab.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200513