Absorption of lower hybrid waves by fast ions
Fast ions, due either to fusion reactions or to other heating methods, could absorb part of the LH wave power, thus limiting the current drive efficiency of the system. If this occurs in JET, and is detectable, the LH wave deposition profile could be studied by varying the ion cyclotron wave deposition profile, and so the absorption capability of fast ions could be analysed, for extrapolation to future devices. In order to develop a theoretical model of the power absorption, a Fokker-Planck 1-D model (in the velocity space) of the LH wave/ion interaction is considered, including both quasi-linear LH wave and ion cyclotron wave diffusion terms. This model is coupled to a deposition code for LH waves, to study the competition in the absorption between ions and electrons. The maximum absorption capability by the minority ions is found by varying the plasma parameters, the minority concentration and mass and the RF power levels. The quasi-linear Fokker-Planck model is discussed, and the deposition code is briefly described. Numerical results are presented and analysed.
Bibliographic Reference: Report: RT/NUCL/90/13 EN (1990) 11 pp.
Availability: Available from Servizio Studi e Documentazione, ENEA, Centro Ricerche Energia Frascati, C.P. 65-00044 Frascati, Roma (IT)
Record Number: 199210167 / Last updated on: 1994-12-02
Original language: en
Available languages: en