Compact Mode Converter System for the Cold Test of Assembled Gyrotrons

A microwave system is described which allows testing of the quasi-optical mode converter in a gyrotron, which is completely assembled except for the attachment of the electron gun. Test results are presented for a TE_6,2,1 gyrotron, and a similar design for a TE_28,7,1 gyrotron is shown.     

Long-pulse and CW tests of a 110-GHz gyrotron with an internal,quasi-optical converter

A high-power gyrotron, employing an internal converter that produces a Gaussian-like output mode, has been designed and tested. The tube employed a TE_22.6.1-mode interaction cavity that was designed for operation at a frequency of 110 GHz. An internal converter, consisting of an advanced launcher design and four mirrors, produced a Gaussian mode that had a relatively uniform profile at the tube output window to minimize the peak power density. Tests on the tube resulted in output power levels of 680, 530, and 350 kW for pulse durations of 0.5, 2.0, and 10.0 s, respectively. Measurements of the temperature of the output window were made during the long-pulse tests. Output power levels of 1 MW were achieved under short-pulse (1 ms) operation and the tube was operated at CW power levels in excess of 100 kW     

Design and emission uniformity studies of a 1.5-MW gyrotron electron gun

We present the design and initial operation of a 96-kV 40-A magnetron injection gun for a 1.5-MW 110-GHz gyrotron. A critical parameter for the successful application of this electron gun is the uniformity of electron emission. The current-voltage curve of emission, at a series of temperatures, is measured. Analysis indicates that the work function of the emitter is 1.6 eV with a (total) spread of 0.07 /spl plusmn/ 0.01 eV. Measurement of the azimuthal emission uniformity with a rotating probe indicates that the work function variation around the azimuth, the global spread, is 0.04 /spl plusmn/ 0.02 eV. The spread due to local (microscopic scale) work function variations is then calculated to be 0.06 /spl plusmn/ 0.02 eV. Temperature variation can be ruled out as the cause of the observed emission nonuniformity.