Reflex-triode geometry of the virtual cathode oscillator



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Texas Tech University


An eight-stage four-hundred kilovolt Marx generator, in connection with a 60 nanosecond pulse-forming line, is constructed and utilized as a pulsed source to power a triode version of the Virtual Cathode Oscillator (Vircator). Eight . I uF capacitors, charged to 50kV each, are switched in series by dry-air pressurized spark gaps. The energy from the bank charges a 23 ohm oil transmission line, breaking a peaking gap when the maximum voltage is reached, delivering a 60 ns-400kV pulse to the diode. The design of the "Reflex-Triode" geometry Vircator is based upon claims of high efficiency by Didenko et al.[l] A previously constructed TTU Vircator includes a unique E-beam source, the "brush" cathode; in which a circular array of pins is used as an explosive field emission source to produce relatively high beam currents. The anode consists of a round wire mesh through which the E-beam passes, generating a dense cloud of negative charge known as a "Virtual Cathode." This initial phase of testing is composed of basic operation of the entire system and baseline output power and efficiency measurements.