The Anomalous Currents In The Front Foils of the JET Lost Alpha Diagnostic KA-2

Cecil, F. E. ; Kiptily, V. ; Salmi, A. ; Horton, A. ; Fullard, K. ; Murari, A. ; Darrow, D. ; Hill, K.

关键词: ALPHA PARTICLES;    APERTURES;    CHARGE EXCHANGE;    DEUTERIUM;    FARADAY CUPS;    GOLD;    NICKEL;    PHOTOEMISSION;    PLASMA;    SIMULATION Alpha ParticlesTokamaks;   

DOI  :  10.2172/1013256
RP-ID  :  PPPL-4620
PID  :  OSTI ID: 1013256
Others  :  TRN: US1102955

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

We have examined the observed currents in the front foils of the JET Faraday cup lost alpha particle diagnostic KA-2. In particular, we have sought to understand the currents during Ohmic plasmas for which the ion flux at the detectors was initially assumed to be negligible. We have considered two sources of this current: plasma ions both deuterium and impurity in the vicinity of the detector including charge exchange neutrals and photoemission from scattered UV radiation. Based upon modeling and empirical observation, the latter source appears most likely and, moreover, seems to be applicable to the currents in the front foil during ELMy H-mode plasmas. A very thin gold or nickel foil attached to the present detector aperture is proposed as a solution to this problem, and realistic calculations of expected fluxes of lost energetic neutral beam ions during TF ripple experiments are presented as justification of this proposed solution.