Effects of the spectral broadening of lower hybrid waves on current drive efficiency in tokamaks
Full current drive operation has been achieved on ASDEX for different ohmic target plasmas, by means of 2.45 GHz lower hybrid waves. Variations of the current drive efficiency up to 50% have been observed, which correlate with the spectral broadening of the pump wave as detected by an electromagnetic probe. Either parametric decay instabilities at the plasma edge or scattering of the lower hybrid waves could be responsible for these effects. The results can be explained within the approximations of available current drive theory with a simple model which assumes that the same process that lead to the frequency broadening also causes a modification of the launched n(parallel) spectrum.
Bibliographic Reference: Report: RT/NUCL/90/10 EN (1990) 12 pp.
Availability: Available from Servizio Studi e Documentazione, ENEA, Centro Ricerche Energia Frascati, C.P. 65-00044 Frascati, Roma (IT)
Record Number: 199210152 / Last updated on: 1994-12-02
Original language: en
Available languages: en