Title :
Switching of circular waveguide H11 mode by plasma of gas microwave discharge
Author :
Artemenko, Sergey N. ; Avgustinovich, Vladimir A. ; Gorev, Stanislav A. ; Igumnov, Vladislav S. ; Novikov, Sergey A. ; Yushkov, Yurii G.
Author_Institution :
Tomsk Polytech. Univ., Tomsk, Russia
Abstract :
The report presents the results of experimental study of switching the H11 mode by gaseous discharge plasma formed in microwave switches made of S-band circular waveguides. The objective of the study was switching executed by a microwave discharge inside a quartz tube located in the polarization plane of the switched wave in a regular waveguide or switching arm of the waveguide H-tee. The main conditions of the effective switching of H11 mode in the waveguide capable to transmit the higher E01 mode as well were determined by model experiments at low power level by imitating a plasma channel by a section of thin wire inserted into the discharge area. The portions of total power in transmitted, reflected and dissipated waves during the switching process in nitrogen, argon and argon and SF6 mixture was also estimated during the experiments run at high power level. The switching was realized inside the tube under insulating gas pressure of ~10-760 Tor and with transmission of microwave pulse with pulse power 2 MW and pulse width of 3mcs along the switch. It was found out that the switching process is more effective during first 10-20 ns. In particular it was determined that during this time the working mode power may be amplified by the plasma of microwave discharge. Therefore the assumption about the possible overestimation of the active microwave pulse compressor amplification with plasma gas discharge switches was formulated. The first data concerning switching of H11 mode in the regular waveguide with the diameter close to the critical diameter for H01 and E11 modes, switching in the H-ee made of such waveguides and switching in the transmitting type cavity which is cut off for the upper resonant modes were obtained. The influence of mode coupling and weak reflections forming resonant cavities inside the waveguide on the switching process were noticed. Operation of working prototypes of S-- and active pulse microwave compressors demonstrated that the use of plasma microwave switches with the H11 mode of circular waveguide allowed producing steady nanosecond microwave pulses with the pulse power of up to 1 GW, pulse repetition frequency of up to 100 Hz and when the power losses were about 1...2 dB.
Keywords :
circular waveguides; discharges (electric); microwave switches; polarisation; E01 mode; S-band circular waveguide; SF6 mixture; circular waveguide H11 mode; gas microwave discharge plasma; insulating gas pressure; microwave pulse compressor amplification; microwave switch; plasma channel; plasma gas discharge switch; polarization plane; power 2 MW; quartz tube; resonant cavity; resonant mode; wave dissipation; waveguide H-tee; Discharges (electric); Electron tubes; Fault location; Microwave amplifiers; Plasmas; Switches;
Conference_Titel :
Plasma Sciences (ICOPS), 2015 IEEE International Conference on
Conference_Location :
Antalya
DOI :
10.1109/PLASMA.2015.7179959