Simulation of a Pulsed 4.7 MW L-Band Crossed-Field Amplifier

Abstract

It is critical to have a standard reference model for crossed-field amplifiers (CFAs) for the research community. We use the TechX 3-D particle-in-cell (PIC) code TechX to model the Stellant Systems L-4953 CFA. This CFA is a pulsed, reentrant, backward wave device with a thermionic cathode operating in the space-charge limited regime. The basic operating parameters are: peak output power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {out}}^{\text {peak}}\approx 5 \text {MW}$ </tex-math></inline-formula> , gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${G}\approx 11.2 \text {dB}$ </tex-math></inline-formula> , pulse duration <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}_{\text {pulse}}={1.8} \mu \text {s}$ </tex-math></inline-formula> , pulse rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{\text {pulse}}={360} \text {Hz}$ </tex-math></inline-formula> , duty cycle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {Du}={0.06}8\%$ </tex-math></inline-formula> , and a frequency bandwidth from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}={1.28} \text {to} {1.35} \text {GHz}$ </tex-math></inline-formula> . This work will present device dimensions, the dc and radio frequency (RF) connection assemblies, and characterize the device performance. Simulations in VSim are used to determine the gain, bandwidth, and transmission characteristics. With the specified anode current of 98 A, a stable 3-electron spoke operation is observed with the simulated gain matching the device within 1 dB. The simulation model is directly compared with supplied device data from 13 devices and accurately predicts the operating voltages within 3% and output power within 10% except for an outlier at 1.28 GHz.