ICEPIC simulation of a strapped non-relativistic high-power CW UHF magnetron with a helical cathode operating in the explosive electron emission mode

The commercial, off-the-shelf (COTS) industrial heating magnetrons are the most powerful non-relativistic Microwave Vacuum Electronic Devices (MVED) operating in the upper part of the UHF band (800-1000 MHz). There are limitations imposed on the magnetron operation by the thermionic cathodes operating in the thermal electron emission mode. Among the most severe limitations are (i) the time the magnetron takes to be ready to operate when necessary (the warm-up time), and (ii) the inability to increase the current without damage in an effort to produce greater microwave power. Recently, the High Power Microwave Division of the Air Force Research Laboratory, Directed Energy Directorate (AFRL/RDH) initiated the project, “Non-thermionic cathode for high power, long pulse, and long lifetime magnetrons.” The project aims at developing a “compact electron emitting cathode capable of re-placing the conventional thermionic source without changing the microwave source operation and eliminating the heater for the thermionic cathode.” This paper presents results of PIC simulations of a strapped non-relativistic UHF magnetron with geometrical and operational parameters similar to those of the high-power industrial heating 915 MHz magnetron, and a helical cathode operating in the explosive electron emission mode producing the maximum available i.e. “space-charge-limited” (SCL) current.