Discrete kinetic eigenmode spectra of electron plasma oscillations in weakly collisional plasma: A numerical study

It has been demonstrated that in the presence of weak collisions, described by the Lenard-Bernstein (LB) collision operator, the Landau-damped solutions become true eigenmodes of the system and constitute a complete set [C.-S. Ng et al., Phys. Rev. Lett. 83, 1974 (1999) and C. S. Ng et al., Phys. Rev. Lett. 96, 065002 (2004)]. We present numerical results from an Eulerian Vlasov code that incorporates the Lenard-Bernstein collision operator [A. Lenard and I. B. Bernstein, Phys. Rev. 112, 1456 (1958)]. The effect of collisions on the numerical recursion phenomenon seen in Vlasov codes is discussed. The code is benchmarked against exact linear eigenmode solutions in the presence of weak collisions, and a spectrum of Landau-damped solutions is determined within the limits of numerical resolution. Tests of the orthogonality and the completeness relation are presented. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789882]