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HIGH AVERAGE-POWER R-F WINDOW STUDY
SPERRY GYROSCOPE CO GREAT NECK N Y
Efforts were made to develop a high average-power r-f window. A study of dielectric window materials revealed that the best are the dense, sintered alumina ceramics and single-crystal synthetic sapphire. Sapphire is the most resistant to damage by electronic bombardment. Beryllia has a slightly higher dielectric loss factor, lower flexural strength, and higher porosity than the best sintered alumina. Dielectric liquids were investigated as possible internal coolants. Tests of experimental window structures at a frequency of 8.35 kmc and a power level of 10 kw produced plots of the temperature rise of each of eight points on the exterior surface. The results proved that thin windows are much more efficient than thick windows, and that the sapphire disc window develops the least heat of all types tested. A high-power ring resonator was constructed for testing windows at higher power levels than are available from tubes. The highest power achieved was 110 kw, and was limited by breakdown at the tuners rather than at the test windows. Author