Fusion Science and Technology / Volume 65 / Number 1 / January 2014 / Pages 10-21
Lecture / dx.doi.org/10.13182/FST13-634
Irreversible energy and momentum transfer from waves to particles for tokamak confinement, heating, and control is based on Landau and cyclotron resonances. Above a stochasticity threshold, these interactions can be viewed as a random walk in energy (action) space within the random phase approximation. We present and discuss the quasi-linear theory describing this random walk with a particular emphasis on the interplay between the dynamical picture (electromagnetic forces) and the statistical description (photons emission/absorption). Landau and cyclotron absorptions in tokamaks are thus derived, and the classical theory of current generation in tokamaks is presented in local and nonlocal regimes.