Numerical and experimental investigations of fusion-relevant beam-plasma instabilities

The growth and evolution of beam-plasma instabilities is of interest in a variety of fields of plasma physics. In fast-ignition inertial confinement fusion this instability may provide an additional ion heating mechanism. In this form of inertial confinement fusion, a deuterium-tritium fuel pellet is compressed by uniformly distributed intense laser radiation forming a high density plasma. A secondary short, high power laser pulse then interacts with the high density plasma, possibly via a conical gold insert, producing a highly relativistic electron beam that propagates through the plasma. During this propagation, the two-stream instability can occur. This instability takes the form of Langmuir waves which may parametrically decay to ion acoustic waves. These ion acoustic waves can then be damped by ion-ion collision providing a heating mechanism in addition to electron-ion collisions. To investigate this behaviour, numerical simulations have been conducted in a lower density and lower temperature regime utilising a two-dimensional particle-in-cell (PiC) code. The parameters used represent a laboratory experiment that is being designed and constructed to provide an experimental benchmark for the numerical predictions.