Collisional damping of electron plasma waves, the primary damping for high phase velocity waves, is proportional to the electron-ion collision rate, nu(ei,th). Here, it is shown that the damping rate normalized to nu(ei,th) depends on the charge state, Z, on the magnitude of nu(ei,th) and the wave number k in contrast with the commonly used damping rate in plasma wave research. Only for weak collision rates in low-Z plasmas for which the electron self-collision rate is comparable to the electron-ion collision rate is the damping rate given by the commonly accepted value. The result presented here corrects the result presented in textbooks at least as early as 1973. The complete linear theory requires the inclusion of both electron-ion pitch-angle and electron-electron scattering, which itself contains contributions to both pitch-angle scattering and thermalization.
Fabrizio Carbone, Giovanni Maria Vanacore, Ivan Madan, Gabriele Berruto, Ido Kaminer, Simone Gargiulo, Luca Piazza, Francesco Barantani, Tom Theodorus Antonius Lummen
Andreas Osterwalder, Sean Dennis Steven Gordon, Junwen Zou, Silvia Tanteri