Design and initial operation of lost fast-ion probe based on thin Faraday films in CHS

摘要

The purpose of this work is to measure lost fast ions as an ion current so as to make quantitative argument on flux of fast-ion loss possible. We have designed and constructed a lost fast-ion probe based on combination of thin Faraday films and small rectangular apertures, called FLIP, for the Compact Helical System. The current generated by escaping fast ions has been successfully measured with the FLIP in neutral-beam-heated plasmas. The FLIP detected increased flux of escaping fast ions while fast-ion-driven magnetohydrodynamics instabilities appear.