Experimental verification plan for a 70% efficient relativistic magnetron with diffraction output (MDO)

It was demonstrated via MAGIC [1] simulations that a relativistic magnetron with axial diffractive output (MDO) could operate at 70% efficiency [2]. In order to experimentally verify this, UNM´s PULSERAD PI-110 electron beam accelerator was modified to provide a 350 kV, 30 ns flat-top pulse with <;4 ns rise time [3]. The MDO was characterized with a B-field scan at this voltage, where 6, 4, and 2 cavities are used to excite the downstream microwaves modes to be radiated. Behavior was predicted for a variety of cathode endcaps used to suppress the downstream drift of electrons; these endcaps include spherical, spherical dielectric coated, spherical magnetic, spherical magnetic dielectric coated, and conical. A diagnostic plan was made in order to capture power and microwave pulse shape/length for several potentially co-existing radiated modes using a calorimeter and microwave diagnostics, as well as measuring the microwave diode´s voltage and current waveforms via D-dot and Rogowski probes. Finally, a pulsed insulating electromagnet system was recently finished.