SIMULATION OF THE EXCITATION OF COAXIAL MODES BY AN ICRH ANTENNA ON A LABORATORY MODEL
The predominant type of edge radiation involves the excitation of coaxial modes between the Tokamak wall and the plasma edge which is seen by these modes as a slightly leaky metallic wall. In order to study the coaxial mode radiation of ICRH launching systems the plasma can be replaced quite accurately by a metal cylinder. In this paper we report results of measurements on a laboratory model of coaxial geometry in which the excitation of coaxial modes by a conventional strip line ICRH antenna is studied. It is experimentally shown that the electrostatic shield is very effective in suppressing the axisymmetric (or TEM) coaxial modes. The use of side limiters around the unshielded antenna or its placement in a wall indentation decreases the TEM coaxial radiation in agreement with theoretical expectations. For higher order coaxial modes (TE waves) no detailed investigation has yet been made ; their order of magnitude seems not to be significantly affected by the use of an electrostatic shield, of side limiters or of the wall indentation.
Bibliographic Reference: 4TH INTERNATIONAL SYMPOSIUM ON HEATING IN TOROIDAL PLASMAS, ROMA (ITALY), MARCH 21-28, 1984 VOL. I, PP. 331- 338 1478 P., VOL. I AND VOL. II, 1984 WRITE TO MONOTYPIA FRANCHI, ST. LUCIA + VIALE UMBRIA NO. 28, 06012 CITTA DI CASTELLO, PERUGIA (ITALY), USD 6
Record Number: 1989124025400 / Last updated on: 1987-01-01
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