Charles Karney: Publication 20/85, Karney(1979e)

C. F. F. Karney.
Stochastic ion heating by a lower hybrid wave: II.
Phys. Fluids, 22(11):2188–2209, November 1979.
E-print: arXiv:physics/0501034 (Mirror).
Princeton Univ. Rept. PPPL-1528 (Apr. 1979) 68 pp.
Reprint: pf79d
DOI: 10.1063/1.862512
BibTeX Entry

The motion of an ion in a coherent lower hybrid wave (characterized by |k_||| << |k_⊥| and ω >> Ω_i ) in a tokamak plasma is studied. For ions satisfying v_⊥ > ω/k_⊥, the Lorentz force law for the ions is reduced to a set of difference equations which give the Larmor radius and phase of an ion on one cyclotron orbit in terms of these quantities a cyclotron period earlier. From these difference equations an earlier result [Phys. Fluids 21, 1584–1599 (1978)] that above a certain wave amplitude the ion motion is stochastic, is readily obtained. The stochasticity threshold is given a simple physical interpretation. In addition, the difference equations are used to derive a diffusion equation governing the heating of the ions above the stochasticity threshold. By including the effects of collisions, the heating rate for the bulk ions is obtained.