HIGH-POWER MICROWAVE TEST FACILITY BASED ON DOUBLE-ANODE RELATIVISTIC TETRODE (DART) OSCILLATORS

High-power microwave (HPM) sources used for testing systems and components at high peak-powers and high energy fluences at the Phillips Laboratory HPM test facility, Kirtland Air Force Base, NM are described. Peak powers of up to 400 MW are radiated using a 150 ns, 650-kV pulse-power device to drive a class of microwave tubes termed double anode relativistic tetrode (DART) oscillators. Single-shot power densities and energy fluences exceeding 100 kW/cm2 and 10 mJ/cm2, respectively, over a frequency band from 650 MHz to 3.5 GHz, are available for testing objects with cross-sections of up to 2000 cm2. The axially extracted DART is a field emission space-charge driven oscillator which utilizes a wide bandpass, high efficiency (approximately 70%) TM01 to TE11 waveguide mode converter. The DART class of devices is particularly useful for facility testing because they 1) provide pencil beam output at high exposure levels; 2) are fully tunable over approximately 25% bandwidth; and 3) are compatible with a wide variety of low cost horns which provide various antenna gains. A 1-MW L-band magnetron provides power densities and energy fluences exceeding 500 W/cm2 and 2 mJ/cm2 for mu-s pulse lengths at repetition rates to 120 Hz. The RF test environment is characterized using redundant in-situ and free-field RF diagnostics and a VAX-based data acquisition and archival system. Facility capability for both single shot and repetitive testing is presented.