PLASMA EDGE PHYSICS WITH SILICONIZATION IN TEXTOR

Citation
U. Samm et al., PLASMA EDGE PHYSICS WITH SILICONIZATION IN TEXTOR, Journal of nuclear materials, 222, 1995, pp. 25-35
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Nuclear Sciences & Tecnology","Mining & Mineral Processing","Material Science
ISSN journal
0022-3115
Volume
222
Year of publication
1995
Pages
25 - 35
Database
ISI
SICI code
0022-3115(1995)222:<25:PEPWSI>2.0.ZU;2-X
Abstract
By using silicon as a material for wall coatings significant improveme nts in the tokamak performance have been obtained. These include the l owest oxygen level ever achieved in TEXTOR, an improved density limit and an enhanced energy confinement also at high central electron densi ties. The present paper gives a survey on the plasma properties under siliconized wall conditions with special emphasis on plasma edge physi cs. The impurity fluxes released from the limiter have been determined as a function of various parameters. An outstanding property of silic on as an impurity in the plasma is its strong influence on plasma edge parameters caused by line radiation. A high radiation level of up to 70% of the input power (1.5 MW) has been achieved, limited by the mech anisms which are responsible for the release of silicon. To describe a nd understand these processes at the plasma edge Od- and 1d-models are used to simulate the highly nonlinear system. The properties are comp ared to plasmas in a boronized machine. Silicon and neon are compared with respect to radiation characteristics and transport to the centre. Remarkable differences in the penetration depths and central densitie s are reported.