Changes in tokamak plasma properties during impurity injection

Journal Article · Thu Apr 01 00:00:00 EST 1982 · J. Vac. Sci. Technol.; (United States)

DOI:https://doi.org/10.1116/1.571526· OSTI ID:5572654

Cohen, S; Cecchi, J; Daughney, C; Davis, S; Dimock, D; Efthimion, P; Finkenthal, M; Fonck, R; Hinnov, E; Hulse, R; Johnson, D; Manos, D; McNeill, D; Medley, S; Meservey, E; Mueller, D; Schivell, J; Silver, E; Suckewer, S; Timberlake, J ; Von Goeler, S

Certain applications of laser blow-off impurity injection, such as ion temperature measurement and spectral line identification, may require the ratio of injected ions-to-plasma electron density to exceed 0.001. To achieve these concentrations we have relied on injection of micron-sized clusters as well as monatomic species. In these cases the injected impurity can no longer be regarded as a nonperturbing trace sourced at the plasma edge. We therefore have studied the variation of plasma parameters in PLT and PDX as a function of the amount of injected impurities, the species mix, and the type of impurity. We find that for ohmically-heated plasmas, impurity injection can increase n-bar/sub e/ more than 4 x 10/sup 12/ cm/sup -3/ without causing disruptions. During Ge-injection experiments where ..delta..n/sub e//n/sub e/ approx.0.05, T/sub e/ initially rises approx.5% on axis and decreases approx.20% at the edge. The plasma current drops 1--3 % and the loop voltage and radiated power both double. Varying the amount of injected impurities changes the peaking and decay times of both high and low impurity charge states by 10--50 %. Analysis of this in terms of altered temperature profiles, impurity penetration profiles and impurity transport is presented. These studies suggest criteria for performing nonperturbing transport experiments.

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• DOE Contract Number: AL02-76-CH0-3073
• OSTI ID: 5572654
• Journal Information: J. Vac. Sci. Technol.; (United States), Vol. 20:4
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
PDX DEVICES
ELECTRON DENSITY
ELECTRON TEMPERATURE
IMPURITIES
ION BEAM INJECTION
PLASMA DENSITY
SPATIAL DISTRIBUTION
TEMPERATURE DISTRIBUTION
PLT DEVICES
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
GERMANIUM
JOULE HEATING
SCANDIUM
X-RAY SPECTRA
BEAM INJECTION
CURRENTS
DISTRIBUTION
DIVERTORS
ELECTRIC HEATING
ELEMENTS
HEATING
METALS
PLASMA HEATING
RESISTANCE HEATING
SPECTRA
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
TRANSITION ELEMENTS
700102* - Fusion Energy- Plasma Research- Diagnostics
700101 - Fusion Energy- Plasma Research- Confinement
Heating
& Production