Collisional damping of Langmuir waves in one-dimensional plasma simulations

The collisional damping of long wavelength Langmuir waves in a one-dimensional particle code plasma simulation is investigated in detail. In particular, it is shown that this damping varies as (n lambda D)-1, is generally independent of wave number, and most importantly, can be reduced significantly by judicious suppression of short wave-length ion fluctuations. All these results prove to be in good quantitative agreement with classical inverse bremsstrahlung theory, if appropriately modified to one dimension. Additionally, simulations showing anomalously large decay rates for thermal Langmuir wave auto-correlation functions are presented. Finally, the equilibrium rate for ion fluctuations is touched upon.