THE ASDEX 100 KEV NEUTRAL LITHIUM BEAM DIAGNOSTIC GUN
The neutral lithium beam gun intended for measurement of the poloidal magnetic field and of the density gradient in the scrape-off layer of ASDEX is described, and test results over a beam energy range of 27 - 100 keV are presented. In the gun, lithium ions are extracted from a solid emitter (beta-Eucryptite) in a Pierce-type configuration, accelerated and focused in a two-tube immersion lens, and neutralized in a charge-exchange cell using sodium.It is found that to produce a particular beam width a certain ratio must be maintained between the extraction and total beam voltages, this relationship depending in turn on the emitter-extractor separation. The principal features which distinguish the ASDEX gun from that employed on W7a are the greater compactness - all the active elements, i.e. emitter, extractor, lens, deflection plates and neutralizer, are contained within 57 cm - and the vacuum vessel, which simultaneously serves as the magnetic shielding.
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY) MENTIONING REPORT IPP III/85, 25 P., 10 FIG., 1983
Record Number: 1989122040400 / Last updated on: 1987-01-01
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