Initial ALT-I pump limiter studies on TEXOR
The ALT-I pump limiter has been used to control the fueling and recycling characteristics of TEXTOR during stable, reproducible tokamak discharges. The module has been operated in three modes: (1) Normal Limiter, with no particle collection, (2) Particle Scoop, with a maximum approx. 2 x 10/sup -3/ torr pressure rise in the 700 liter unpumped collection chamber, and (3) Pump Limiter, with up to approx. 10,000 1/s pumping speed and particle removal rates of up to 6 x 10/sup 20//s. In a comparison of operation in modes (1) and (3) using identical gas fueling programs, the total core electron number decreased by as much as 50%. The effective TEXTOR particle confinement time, tau/sub p/* = tau/sub p//(1-R), was decreased by a similar ratio. Within the throat region, during typical operation, electron densities and temperatures were 6 x 10/sup 11/ to 2 x 10/sup 12//cm/sup 3/ and 15 to 30 eV. These conditions are representative of an operating regime in which there is high reionization of neutrals, but no change in incoming plasma parameters in the throat region. Energetic particles near the deflector plate were observed. During a gradual insertion of TiC-coated ALT-I beyond the stainless steel TEXTOR main limiters, the density of Ti in the plasma increased to a level similar to those of Cr and Fe. The gas injection fueling efficiency while puffing hydrogen directly into the plasma at the pump limiter tangency point was measured to be > 0.9. These results are discussed in conjunction with measurements of particle flows within ALT-I and other plasma diagnostics to characterize pump limiter operation on TEXTOR.
- Research Organization:
- Sandia National Labs., Livermore, CA (USA); Sandia National Labs., Albuquerque, NM (USA); California Univ., Los Angeles (USA); Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.); Association Euratom-Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 7092328
- Report Number(s):
- SAND-84-1350C; CONF-840520-15; ON: DE84014005
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700209* -- Fusion Power Plant Technology-- Component Development & Materials Testing
ALLOYS
CARBIDES
CARBON COMPOUNDS
CHROMIUM ALLOYS
CLOSED PLASMA DEVICES
CONFINEMENT
CORROSION RESISTANT ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
LIMITERS
PERFORMANCE
PLASMA CONFINEMENT
STAINLESS STEELS
STEELS
TEXTOR TOKAMAK
THERMONUCLEAR DEVICES
TITANIUM CARBIDES
TITANIUM COMPOUNDS
TOKAMAK DEVICES
TRANSITION ELEMENT COMPOUNDS
VACUUM SYSTEMS