Chaotic instabilities and density profiles in a crossed-field electron vacuum device

Crossed-field electron vacuum devices are resonant devices. When properly tuned, they operate at a single frequency and have an average background distribution. Thus one can use the cold-fluid equations and a Fourier decomposition to separate the physical quantites into a background (DC) mode and a pump (RF) mode. We have improved our previous calculations on these devices and can now understand how the background plasma density varies and evolves as the RF wave travels down the slow-wave structure. We study the evolution of an RF pump wave through the device and find that in general, chaotic (period-2) instabilities can occur if the device is too long. We also present results for the high magnetic field case, (typical CFA/magnetron regime), for the moderate magnetic field case (ultra-low noise regime), and discuss how these solutions correspond to device operation. Lastly, we discuss our results and point out future work in need of study.