Development Of A Phase-Controlled Magnetron Experiment Using A Modulated Electron Source

Abstract

Our group is developing a phase-controlled magnetron using electron current injection locking. Our prior 2D simulation work [1] using the PIC code Vsim has shown phase-locking of a rising sun magnetron by modulating the electron injection to control formation of the electron spokes. We are building a magnetron experiment that uses the 10-cavity, L3 Communications, CWM-75KW cooker magnetron. Our experiment will operate at lower power $(\sim 1$ kW) and low current (150 mA) with an operating frequency around 909 MHz. The experiment will operate in pulsed mode with $\mathrm {a}10 \mu \mathrm {s}$ pulse width to reduce the demand on the electron source of Gated Field Emission Arrays (GFEAs). The modulated current will be provided by GFEAs [2] that have demonstrated current densities of 100 A/cm 2 at a gate to emitter bias of <75V, but the experiment will require <200 mA/cm 2 and a modulated gate bias of <30V using a DC offset. The experiment will utilize a 10-sided faceted cathode constructed of a lower temperature co-fired ceramic (LTCC) that uses electron hop funnels to protect the GFEAs. The cathode structure fabrication, GFEA implementation, drive electronics, and drive scheme will all be presented along with preliminary experimental results of the GFEA operation in the magnetron system.