Computational Observation of Collisionless Damping of Langmuir Waves in Relativistic Plasmas*

Recent inertial confinement fusion experiments have generated underdense plasma conditions believed to be in the 10-20 keV regime. In this regime, Langmuir waves excited by laser light instabilities will have phase velocities for which a relativistic treatment is required. We conduct basic physics studies of such Langmuir waves using direct simulation of the relativistic Vlasov equations. Building on prior work, we address the significant computational cost associated with high-dimensional phase space approximation using high-order accurate numerical schemes as a means to reduce the cost required to deliver a given level of error in the computed solution. Fully conservative and minimally diffuse difference formulations of order four and six are used. Additionally, theoretical techniques indicate the existence of Langmuir waves with superluminal phase velocities in relativistic plasmas. The existence of these waves is investigated using simulations.

 

*This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344