Oscillation starting condition of a K-band oversized backward wave oscillator (BWO) is investigated experimentally. Periodically corrugated slow-wave structure (SWS) is used, which is designed for K-band operation in a weakly relativistic region, i.e. 30-80 kV. The beam current is in the range of 50- 00 A. It is shown experimentally that there exists a critical beam energy (starting energy) for the meaningful radiation. The starting energy is more critical than the starting current in the oversized BWO. It decreases by increasing the SWS length. Above the starting energy, the output owers up to about 100 kW are obtained. The typical frequency observed is about 23 GHz. Nonaxisymmetric hybrid HE11 mode as well as axisymmetric TM01 mode is observed. The operation mode is able to be controlled by the SWS length and the magnetic field strength.
雑誌名
Progress in plasma theory and understanding of fusion plasmas : Proceedings of 13th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion (ITC-13), December 9-12, 2003, Toki-city, Japan
ページ
703 - 706
発行年
2004-12
出版者
The Japan Society of Plasma Science and Nuclear Fusion Research