Characteristic of vircator output at various A-K gap distances with diode perveance

Summary form only given, as follows. The purposes of this research are to investigate (1) the relationship A-K gap distance and area with perveance characteristics of diode in vacuum, (2) the relationship A-K gap distance with microwave output frequency and power. At the vacuum the pressure of 10-5 Torr are employed, it was found that the diode geometrical characteristics for various A-K gap distance and area. At vacuum regime, we measured diode current and voltage by using a B-dot probe and and a C-dot probe respectively. From this, we could get the experimental diode perveance equation. The perveance are experimentally found to scale as p=4.78/spl times/10/sup -7//d/sup 1.49/ (d:A-K gap distance) when the cathode diameter are about 3 cm When the cathode diameter is to be more smaller than 3 cm, the diode perveance scaling law is to be approach p/spl prop/d/sup 1/. The other case, the cathode diameter is to be more longer than 3 cm, the perveance is to be approach p/spl prop/d/sup 2/. From this results, we could calculate the A-K gap distance variation by sheath plasma expansion on the cathode and anode surface. We could applied the empirical preveance to the Vircator system. When electron beam is generated from the diode, sheath plasma on a electrodes expand with each other. This plasma expansion control the electron beam current density that is generated from the diode. It was found that the diode A-K gap distance have an effect on the current density and microwave output.