MODELING OF THE CONTINUUM X-RAY-SPECTRA PRODUCED BY ANISOTROPIC ELECTRON DISTRIBUTIONS IN TOKAMAK PLASMAS UNDER LHCD CONDITIONS

The continuum x-ray spectrum resolved in angle due to the axisymmetric anisotropic electron velocity distribution F(upsilon) produced during lower hybrid current drive (LHCD) in tokamak plasmas is modelled. The radiative processes considered are the electron-ion (e-i) and electro n-electron (e-e) bremsstrahlung, and the direct radiative recombinatio n (DRR) averaged over the velocity distribution F(upsilon) predicted b y the one-dimensional Fokker-Planck model. The relativistic cross sect ions for the e-i and e-e bremsstrahlung in the Born approximation and corrected by the respective Elwert factors are used in the computation . Since the DRR becomes negligible relative to the bremsstrahlung in t he relativistic domain under LHCD conditions, the non-relativistic cro ss section for DRR in the dipole approximation is used for simplicity and analytical expressions cast into real form are given to evaluate t he hypergeometric series solution of the form function for all shells and levels nl. The mathematical expressions are also given to obtain t he total number of photons in a detector looking through a plasma colu mn for a two-aperture system and sample calculations for LHCD conditio ns on the Tokamak de Varennes, are presented.