COLLISIONAL DAMPING OF TRANSVERSE WAVES IN A PLASMA

The Landau (Fokker-Planck) equation is used to calculate the temporal damping rate for the small amplitude, transverse electromagnetic mode (linearly polarized) for (a) no external fields, and (b) a uniform magnetic field. In (a) the damping rate is found by using a solution to the kinetic equation to evaluate the electron current. This damping may be recovered from the zero field limit of a previous result of Buti for the right circularly polarized mode after a correction is made in that result. In (b) a moment equation approach is used, and the heat flow tensor components are evaluated using a solution to the kinetic equation. The damping rate is ωI ≃ -1/2(2/π)1/2ωp3/ω 02 ln Λ/Λ [1 - λD 2k2ωp4/ω 02(ω02 - Ω 02) (2ω02 - Ω02) + 2λD2k 2ωp2/5(ω02 - Ω02)2 (5ω02 + Ω02 + 3/√2 (ω02 + Ω02))], where ω02 = c2k2 + ωp2. The damping in (b) depends on the magnetic field only in the thermal correction, and reduces to that in (a) when magnetic effects are negligible.