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A quasilinear operator for wave–particle interactions in the electron cyclotron range is derived using the cold plasma dispersion relation. The finite width of the beam implies a broadening of the resonance layer in the velocity space which allows the use of a numerically efficient treatment of the operator. The specific case of a pure heating injected at the outer mid-plane is then treated. It allows to treat the beam propagation and absorption easily, simplifying the implementation of the source term in the gyrokinetic code. This specific case is implemented in the gyrokinetic particle-in-cell code ORB5 using a Langevin approach. The derivation and verification of the source operator are presented. [ABSTRACT FROM AUTHOR]

Suprathermal electron dynamics in real and momentum spaces plays an important role in the physics of electron cyclotron current drive (ECCD), in particular for predicting the wave driven current. In the TCV tokamak, a hard x-ray spectroscopy system equipped with digital pulse detection enables detailed studies of the creation and relaxation of suprathermal electrons. The time evolution of hard x-ray spatial profiles and energy spectra is observed utilizing a minimally perturbative ECCD modulation technique. Time-dependent Fokker-Planck modeling combined with a hard x-ray synthetic diagnostic is used to interpret experimental results and test various suprathermal electron transport models. The comparison suggests a dependency of the radial transport on the EC wave power. [ABSTRACT FROM AUTHOR]