Aspects of fundamental deuterium and second harmonic tritium heating in fusion plasmas

Summary form only given, as follows. This work examines fundamental deuterium and second harmonic tritium heating in ITER and TFTR. The fundamental heating scenario is (D)T in an ITER-like plasma with baseline parameters (R/sub major/=6 m; r/sub minor/=2.2 m; B/sub minor/=4.85 T; n/sub e/=9.0/spl times/10/sup 19/ m/sup -3/; T/sub e/=10-15 keV). The enhanced fusion reactivity resulting from the non-Maxwellian deuterium population (given by Stix´s quasi-linear formalism) has been evaluated numerically. The absorption and reflection coefficients for the fast wave are calculated using the full-wave code XWAVE. For ITER, we find that the presence of the (D-T) hybrid resonance can give rise to a substantial enhancement of the local a particle absorbed power density and significant reflection. When the hybrid resonance layer is moved to the magnetic axis, the single-pass alpha power absorption coefficient can reach up to 70% (with greatly reduced reflection) for parameters corresponding to an advanced ITER design. The behavior of the distribution function of the alphas has also been investigated using FPPRF, a bounce-averaged Fokker-Planck code. These results can be relevant to a possible alpha current drive scheme in ITER-class machines. The second harmonic tritium heating scenario is a D-T plasma with hot D and T beams, and small concentrations of He/sup 3/ and /spl alpha/. The plasma parameters have been chosen from TRANSP calculations of recent D-T runs in TFTR, and the analysis is carried out with SEMAL, a global full-wave code based on a finite-element method. We find that the absorption by fusion alphas can be significant for large parallel wave numbers.