Plasma bombardments in the diode in Ka-band coaxial transit-time oscillator

• Main Authors: Lili Song, Juntao He, Ankun Li, Longzhou Yu
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2018-03-01
• Series: AIP Advances
• Online Access: http://dx.doi.org/10.1063/1.5019396

Plasma is a non-ignorable factor in a high power generator. In this paper, plasma bombardments in the diode region are found in experiment on a Ka-band transit-time oscillator. Microcosmic and energy dispersive analysis has been done first on the plasma spots. Based on the Carbon contents in different areas of the diode, a physical model describing the progress of the plasma from appearance to expansion is built. Subsequently, simulations on the plasma expansion have been done with particle-in-cell code calculation. The result agrees well with the model proposed above. Finally, a special structure is adopted in the improved Ka-band coaxial TTO to suppress or even avoid the plasma Bombardment. The study is of significance to generators for long-pulsed and repetition operation.