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Abstract

To increase the RF power throughput to a plasma the secondary electron emission on the waveguide walls and subsequent electron multiplication which cause multipactor breakdown effect must be reduced. The most radical method of solving this problem seems to be the use of metals or coatings with secondary emission yield less than unity. Surface treatment like cleaning or baking can reduce arcing and gas desorption in the waveguide and, as result, the secondary electron yield will be lowered too. We investigated the boundaries of the multipactor region at relatively high frequencies and the energy range of the primary electrons impacting onto the waveguide wall necessary for the suppression of the multipactor discharges. These conditions are estimated theoretically and established experimentally for two kinds of coatings (graphite, TiC) on AISI 304 stainless steel. A study is made of the deactivation of the waveguide walls for the FT coupling structure with the aim of reducing the secondary emission coefficient without affecting the quality of the system.

Additional information

Authors: FRANCONI E ENEA, CENTRO RICERCHE ENERGIA FRASCATI, ROMA (ITALY), ENEA, CENTRO RICERCHE ENERGIA FRASCATI, ROMA (ITALY)
Bibliographic Reference: 4TH INTERNATIONAL SYMPOSIUM ON HEATING IN TOROIDAL PLASMAS, ROMA (ITALY), MARCH 21-28, 1984 VOL. II, PP. 1201-1207 1478 P., VOL. I AND VOL. II, 1984 WRITE TO MONOTYPIA FRANCHI, ST. LUCIA - VIALE UMBRIA NO. 28, 06012 CITTA DI CASTELLO, PERUGIA (ITALY), PRI
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