Impurity Induced Neutralization of MeV Energy Protons in JET Plasmas
A neutral particle analyzer (NPA) was deployed for measurement of distribution function of MeV energy protons driven by high power ion cyclotron resonance frequency heating of deuterium plasmas in the hydrogen minority scheme (D(H) ICRF heating). Unexpectedly, efficient neutralizing of MeV energy protons was observed in the plasma center, without recourse to injection of a beam of atoms to provide charge donors for charge-exchange (CX) neutralization reactions. This paper presents a model elucidating the role of carbon and beryllium, the main impurities in JET plasmas, in this process and establishes charge exchange between hydrogen-like ions of the impurities and protons as the main neutralization process. A model calculation for deducing the proton energy distribution function f(Ep) from measured hydrogen flux is described. Uncertainties in cross-sections and their effect on the inferred f(Ep) are examined.
Bibliographic Reference: Report: JET-P(95)47 (1995) 46pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199610330 / Last updated on: 1996-03-29
Original language: en
Available languages: en