Journal of Microwave Power and Electromagnetic Energy (JMPEE)

 

TITLE

A Cyclotron-Wave Rectifier for S-Band and X-Band [PDF]

AUTHORS

D. C. Watson, R. W. Grow and C. C. Johnson

1970

5

2

72-85

YEAR

VOLUME

ISSUE

PAGES

 

Abstract

A device for converting microwave power into either DC power or low-frequency AC power has been investigated both theoretically and experimentally. Rotational
energy is stored in an electron beam by a Cuccia coupler, then converted to longitudinal energy by interaction with a space-dependent DC magnetic field, and finally recovered as electric energy by a depressed collector. A simple kinematic analysis demonstrates that the Cuccia coupler can convert large amounts of microwave power into electron beam rotation. Limits on the electric field strength and asynchronism between signal frequency and cyclotron frequency are established for both classical and relativistic coupler operation. Efficiency analyses of the process of conversion from orbital energy to DC electric energy, both classical and relativistic, indicate that the efficiency exceeds 95 per cent for a particular range of operating conditions. As an AC power supply, the device responds to the modulating frequency of the signal. Theory predicts near-negligible harmonic distortion as well as flatness of frequency response from DC to about 1.0 MHz modulating frequency. Four tubes and a prototype (with "artificial" coupler) were tested experimentally. The first three tubes exhibited efficiencies up to 22 per cent, being hindered by reflection of electrons into the coupler. Certain design changes were tested on the prototype, where efficiencies from 36 per cent to 75 per cent were obtained. Incorporating these design changes into the fourth tube yielded measured efficiencies of up to 34 per cent, or when corrected to disregard unusually large cavity losses, up to 59 per cent. Experimental tests of the tube as an AC converter yielded excellent frequency response and about 20 per cent second-harmonic distortion. It is concluded that the theoretical foundation of efficiency predictions has thus far been based on too-optimistic assumptions.