Vacuum windows for frequency-tunable high-power millimeter wave systems

H.-U. Nickel

doi:10.1117/12.2298347

14 December 1992 Vacuum windows for frequency-tunable high-power millimeter wave systems

H.-U. Nickel

Proceedings Volume 1929, 17th International Conference on Infrared and Millimeter Waves; 19296E (1992) https://doi.org/10.1117/12.2298347
Event: 17th International Conference on Infrared and Millimeter Waves, 1992, Pasadena, CA, United States

Abstract

Electron cyclotron wave (ECW) systems for future fusion experiments will require frequency-tunable high-power sources such as step-tunable gyrotrons, cyclotron autoresonance masers, or free electron masers. Their use would allow a selective local heat deposition and current drive in the plasma without using mechanically steerable antenna mirrors inside the vacuum chamber. Since the bandwidth of conventional single-disk or double-disk windows is rather low, it is necessary to develop special broadband windows that are able to withstand the high power level (> 0.5 MW) required in ECW-systems. Fig. 1 gives an impression of the frequency dependence of the power reflection coefficient of typical gyrotron windows (SDW, DDW) used for 140 GHz and of a proposed broadband window (BBW). SDW corresponds to a single disk window of polycrystalline (p.c.) BN and DDW to a double disk window of sapphire which is face cooled by a low loss dielectric coolant (FC 75). BBW indicates a simple broadband window as described below.

Citation Download Citation

H.-U. Nickel "Vacuum windows for frequency-tunable high-power millimeter wave systems", Proc. SPIE 1929, 17th International Conference on Infrared and Millimeter Waves, 19296E (14 December 1992); https://doi.org/10.1117/12.2298347

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