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A thermal management concept providing high heat flux capability for High Power Microwave (HPM) source devices used in Directed Energy Weapon (DEW) Systems is presented. Obstacles to the practical application of DEW to aircraft require effective solutions to high heat flux thermal management. Our approach utilizes enhanced cooling mechanisms (subcooled nucleate flow-boiling) coupled with an optimized cooling channel geometry fully integrated within the HPM source device structure. The concept developed has demonstrated effective cooling for heat fluxes up to 900 W/cm2. The design and integration of our thermal management system with HPM source hardware is presented. In addition, experimental testing validating the thermal capability and demonstrating the overall operation of the HPM pulsed-power system is discussed.

Microstructural evolution of a Mo-10W-2Re-0.5HfC alloy was studied in the temperature range of 298 K to 2200 K. The typical characteristics of the microstructure were curly deformation bands, with nucleation at boundaries and subgrain coalescence. The recrystallization temperature of the Mo-10W-2Re-0.5HfC alloy was determined to be near 1950 K, which is comparable with 2125 K for W-4Re-0.35 HfC and 2000 K for W-0.35 HfC. Microhardness tests were performed before and after 1 hour of vacuum annealing and the results indicate that the mechanical strength of Mo-10W-2Re-0.5HfC is lower than that of W-4Re-0.35 HfC or W-0.35 HfC. X-ray diffraction and pole figures indicate that this particular alloy exhibits the primary texture (110) and secondary texture (112) which is normally observed in B.C.C. metals such as Molybdenum. The creep strengths of W-4Re-0.35HfC, TZM-Mo, and W-25Re-30Mo were evaluated and compared at the same stress level.