Modelling of the interaction of energetic ions with lower hybrid waves on JET

Ion tail up to several MeV are generated and confined in the Jet plasma during Ion Cyclotron Heating (ICRH) experiments. When injecting Lower Hybrid Radiofrequency (LHRF) power at 3.7 GHz, such ions interact with LH waves limiting the current drive efficiency of the LH system. To study this problem a 1-D model (in the velocity space) for the wave-ions interaction has been developed which includes, besides the collisional diffusion and drag, the quasilinear LH and ICRF diffusion terms. To calculate the competition in the absorption between electrons and ions this model has been coupled to a deposition code for LH waves. In sec. 1 the 1-D model and the deposition code are presented. Sec. 2 is devoted to the discussion of the numerical results. Then conclusion follow. (author) 7 refs., 4 figs