Accession Number:

ADA230382

Title:

Mode Selection by Priming in an Over moded Electron Cyclotron Master

Descriptive Note:

Final rept. 25 Sep 1989-24 Sep 1990,

Corporate Author:

UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF ELECTRICAL ENGINEERING

Personal Author(s):

Report Date:

1990-09-24

Pagination or Media Count:

57.0

Abstract:

It has been found that an externally injected signal can strongly influence the steady-state electromagnetic mode in which a pulsed electron cyclotron maser ECM operates. A careful experimental examination reveals that the process by which this occurs is similar to the oscillator phase priming noted previously in magnetron work. It is found here that the degree of mode control depends on the injected signal power level relative to the ECM noise power level, frequency, and time of application. Mode control is obtained at power level relative to the ECM noise power level, frequency, and time of application. Mode control is obtained at power levels nearly four orders of magnitude below that of the steady-state ECM output power and over frequency bandwidths several times that of the cavity resonance band. The optimum input signal is a circularly polarized wave, co-rotating with the electron cyclotron motion. The experimental results are compared with a quasilinear coupled-mode theory. The theory is used to provide analytic predictions of the temporal mode evolution through third order coupling. The comparison with experiment indicates that higher order terms are non-negligible in some regimes of operation. However, this model suitably predicts ECM steady state operation over much of the operating parameter space and gives a qualitative understanding of the role of the external signal and pre-oscillation noise in the mode selection process. Mode priming may enable stable and efficient single-mode operation of the ECM and other overmoded sources of coherent radiation.

Subject Categories:

  • Lasers and Masers
  • Particle Accelerators

Distribution Statement:

APPROVED FOR PUBLIC RELEASE