A FORCED GAS-COOLED SINGLE-DISK WINDOW USING SILICON-NITRIDE COMPOSITE FOR HIGH-POWER CW MILLIMETER WAVES

Silicon nitride composite as a candidate of a window material for high power CW (Continuous Wave) millimeter-waves was high power tested esp ecially with a surface cooling by impinging gas nitrogen jets on the s ingle-disk surface. Gas-cooling dramatically suppressed the temperatur e of the window disk even with gas flow rate of around 100 l/min. With gas cooling of 4651/min., 130kW CW power of HE11 mode could be transm itted through the silicon nitride window with a diameter of 88.9mm. Th e peak window temperature was completely saturated on 123.6 degrees C. Without gas-cooling it did not saturate and reached 323 degrees C dur ing 30 seconds pulse. A possibility of 1MW CW single disk Brewster win dows with a forced gas-cooling is discussed, resulting in convinced pr ospects of the windows with realistic size and thickness.