Emission of microwave and millimeter wavelength radiation during hollow cathode discharge operation of the back lighted thyratron

Abstract

Experimental observation of pulsed radiation ranging from ∼20 GHz to above 100 GHz during the hollow cathode discharge phase of operation of a back-lighted thyratron is reported. The discharge is operated with 120 mTorr Ar gas at 20 kV initial voltage. Pulsed radiation was observed for ∼50 ns, and an electron beam with energy of ∼20 keV was also observed. The observations are correlated with plasma processes predicted in recent computer simulations. The sudden turn-off of the radiation is believed to be a result of plasma expansion and sheath contraction inside the hollow cathode region. A method for varying the pulse length is discussed.

Pseudospark-based electron beam and Cherenkov maser experiments

“…In the experiment, there was no external input seed signal from an external microwave radiation source. The microwave emission from the PS discharge acted as the input signal to the amplifier, i.e., the input signal to the Cherenkov maser was generated by the pseudospark discharge itself and was consistent with experiments conducted by Liou et al 14 and Ramaswamy et al, 15 who observed a similar broadband low-power microwave signal from a pseudospark discharge. As shown in Fig.…”

“…These results demonstrated that the maser magnification grew from the emission from the PS discharge itself. 14,15 The frequency range of the microwave radiation from the Cherenkov maser amplifier was measured by applying different cylindrical cutoff filters in the waveguide and comparing this signal with a signal from a nonfiltered reference detector. Using this method, both the Cherenkov maser output and the emission from the PS discharge were analyzed.…”

“…5,6 It is therefore potentially very attractive as an electron beam source for high power generators of electromagnetic radiation, such as free-electron lasers ͑FELs͒, 7 cyclotron autoresonance masers ͑CARMs͒, 8 and Cherenkov masers. [9][10][11][12][13] While there has been a great deal of experimental investigation of the pseudospark discharge characteristics and the microwave radiation accompanying the passage of its electron beam through a low pressure gas, 14,15 the experiment reported here is different in that the pseudospark-sourced electron beam has for the first time been applied in a freeelectron maser device. 16 This experiment involved a Cherenkov maser amplifier driven by an electron beam of 10 A, 70-80 keV, and diameter 3 mm from an 8-gap pseudospark discharge system.…”

Generation and application of pseudospark-sourced electron beams

“…The HCP beam was initially applied in a Cherenkov maser interaction with the background seed signal that was generated from the PS discharge itself [11,12]. The schematic setup of the initial PS-based Cherenkov maser experiment is shown in figure 4.…”

Pseudospark Experiments: Cherenkov Interaction and Electron Beam Post-Acceleration

“…Another interesting result was the discovery that the small background signal was always present even without the guide B-field or dielectric lining in the waveguide. These results demonstrated that the microwave radiation grew from the background seed signal, which seemed to be from the PS discharge itself [9], [10].…”