Accession Number : ADA189151

Title :   Mode Priming in an Overmoded Gyrotron Oscillator.

Descriptive Note : Memorandum rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : McCurdy, Alan H ; Armstrong, Carter A

PDF Url : ADA189151

Report Date : 19 Oct 1987

Pagination or Media Count : 46

Abstract : Axial mode control in a gyrotron oscillator is accomplished by injection of an external signal into the oscillator. The mechanism by which the selection technique works is that of priming, where the injected signal is required only during the early stages of oscillation growth. Like phase priming, mode control can be obtained with an external mode than any other. It is found that the external signal can select a mode when the free gyrotron operation skips between modes from pulse to pulse. Also, in certain conditions, a single stable mode can be changed to a different mode by a priming signal. Finally a case is studied where a bistable system (two simultaneous modes) is reduced to a single mode because of the external signal. Mode control is used as a diagnostic to investigate the coupling of an external electromagnetic wave to the electron beam via electron cyclotron resonance absorption. Beam-wave coupling is studied as a function of the polarization of the input drive signal. It is found that the external electromagnetic signal couples best when launched as a right-hand circularly polarized wave. The theoretical ratio (55.2) of the coupling factors for the right- and left-hand electromagnetic waves is found to be consistent with the experimentally value within the uncertainties of the measurement.

Descriptors :   *GYROTRONS, *OSCILLATORS, *PUMPING(ELECTRONICS), *CHARGE TRANSFER, BISTABLE DEVICES, CIRCULAR, CONTROL, COUPLING(INTERACTION), CYCLOTRON RESONANCE, DRIVES, ELECTROMAGNETIC RADIATION, ELECTRON BEAMS, EXTERNAL, GROWTH(GENERAL), INPUT, OSCILLATION, POLARIZATION, PULSES, RATIOS, RESONANCE ABSORPTION, SELECTION, STABILITY, SYNCHRONISM, ELECTROMAGNETIC PULSES

Subject Categories : Electricity and Magnetism
      Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE