Beam modulation in double gap virtual cathode oscillator

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Electrical and Electronics Engineering, Turkey

Approval Date: 2018


Supervisor: ŞİMŞEK DEMİR


Vircator is a promising high power microwave device when its simplicity, frequency tunability, lack of external magnetic field source are considered. Vircator gains importance especially susceptibility testing to electromagnetic pulses of electronic equipments with its tunability. Apart from advantages, main bottleneck of the vircator is its low efficiency. Tunability and efficiency enhancement studies are still continued in literature. Double gap vircator draws attention due to its tunability, generation frequency stability and microwave radiation efficiency result from beam modulation. This thesis examines double gap vircator in terms of tunability under external signal injection, effect of both plungers and coupling window on output electromagnetic power. With signal injection, efficiency increase, due to earlier start time, is obtained and frequency locking behavior of vircator is observed. For the various configurations of plungers, theoretical cavity field distributions are analyzed and it is obtained that efficiency is maximized when field distribution on beam center is at maximum. Tuning procedure for double gap vircator is developed and its applicability for different AK gap distances and gap voltages are shown.