A quantitative analysis of the effect of ELMs on H-mode thermal energy confinement in DIII-D

Conference · Mon Jun 01 00:00:00 EDT 1992

OSTI ID:7113302

Schissel, D P; Osborne, T H; Carlstrom, T N ^[1]; Zohm, H ^[2]

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1. General Atomics, San Diego, CA (United States)
2. Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

The desire to reach ignition in future tokamaks the energy confinement time critical parameter. The most promising enhanced (over L-mode) confinement regime is the H-mode, discovered on ASDEX with neutral beam heating, and then confirmed with various auxiliary heating sources on numerous machines. The knowledge of how H-mode {tau}{sub E} depends on different parameters is of chemical importance to the performance predictions for next generation devices. Inter-machine H-mode total and thermal energy confinement ({tau}{sub th}) scalings, which are being utilized to predict ITER thermal energy confinement, have been created for discharges where the Edge Localized Mode (ELM) instability has not been present. Confinement scaling research hm concentrated on this ELM-free H-mode phase mostly owing to the difficulty of characterizing ELM behavior. To date, long pulse H-mode operation has only been achieved by utilizing ELMs to flush out unpurities and prevent radiative collapse of the discharge. Unfortunately, accompanying the ELMS is a decrease of the plasma stored energy due to the expulsion of particles near the edge of the discharge resulting in a reduction of the steep edge electron density gradient. In order to predict ITER's H-mode {tau}{sub th} in the presence of ELMS, an estimated 25% confinement degradation factor has been applied to the ELM-free predictions. Our work, summarized in this paper, indicates that this 25% reduction factor is too large and instead a value of approximately 15% would be more appropriate.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114
• OSTI ID: 7113302
• Report Number(s): GA-A-20942; CONF-920610-11; ON: DE92017704
• Resource Relation: Conference: 14. international conference on plasma and 19th EPS conference on controlled fusion and plasma physics, Innsbruck (Austria), 29 Jun - 3 Jul 1992
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DOUBLET-3 DEVICE
H-MODE PLASMA CONFINEMENT
EDGE LOCALIZED MODES
BEAM INJECTION HEATING
CONFINEMENT TIME
PLASMA INSTABILITY
CLOSED PLASMA DEVICES
CONFINEMENT
HEATING
INSTABILITY
PLASMA CONFINEMENT
PLASMA HEATING
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700310* - Plasma Confinement- (1992-)