1 December 1990 Tunable 35-200GHz gyrotron
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Proceedings Volume 1514, 15th International Conference on Infrared and Millimeter Waves; 15146A (1990) https://doi.org/10.1117/12.2301636
Event: 15th International Conference on Infrared and Millimeter Waves, 1990, Orlando, FL, United States
Abstract
The extended frequency tuning range of the Strathclyde University gyrotron will be demonstrated. The gyrotron consisted of a field-immersed, field emission cold cathode and a shaped anode cavity. The cavity was oversized with an ill-defined boundary at one end. This system could therefore support the oscillation of a very large number of TEpqs modes. The maser was thus highly tunable via differential mode excitation. A heterodyne technique was used to demonstrate the maser oscillation in the Ka-band (26.5-40GHz) , with the maser oscillating at 35GHz in the TE01 mode. Previous to this, a quasi-optical diffraction grating spectrometer was used to show the maser was oscillating under different conditions respectively, single and multi-mode in the W-band (75-110GHz) and multimode in the G-band(140-220GHz). To control the output beam a quasioptical mode converter has been successfully developed. This converts various TEpq modes into a Gaussian beam. Studying the output of the maser, the mm-wave pulse has been shown to consist of a -100ns envelope containing -2ns pulses spaced -5ns apart. Although this behaviour may have several explanations, some of the most recent code simulations predict this behaviour as a result of mode beating in the complex transient start-up of the maser oscillation. With this gyrotron supporting not only many transverse modes but also several longitudinal modes, such beating is a likely consequence.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. N. Spark, S. N. Spark, } "Tunable 35-200GHz gyrotron", Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 15146A (1 December 1990); doi: 10.1117/12.2301636; https://doi.org/10.1117/12.2301636
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