Two-stream instability in plasma klystron

Summary form only given. Researchers at the Air Force Research Laboratory´s (AFRL) Directed Energy Directorate have reproduced previous numerical simulations1 of a plasma wakefield klystron. This device was designed to produce electron beam bunching by exciting oscillations in a background plasma, as opposed to the more standard use of an RF structure for this purpose. Using AFRL´s state-of-the-art computer simulation software package, the Improved Concurrent Electromagnetic Particle In Cell (ICEPIC) code, we obtained results similar to the previous work, and may have obtained given additional insight into the cause of the observed behavior. As opposed to wakefield oscillation, ICEPIC simulations indicate that the two stream plasma instability is a much better candidate for causing the device´s simulated behavior. Trends in the simulations agree with expectations from two stream instability theory, and thresholds where the instability grows in simulation qualitatively agree with theoretical predictions. Such thresholds would not be present if the wakefield oscillations were the source of the device´s behavior.