A SMALL-SIGNAL ANALYSIS OF THE ELECTRON CYCLOTRON BACKWARD-WAVE OSCILLATOR
STANFORD UNIV CA MICROWAVE LAB
Pagination or Media Count:
A small signal analysis is presented of the electron cyclotron BWO. The method used is the normal-mode expansion type of analysis. The electromagnetic field existing in the circuit in the presence of RF current is expanded as a double infinite series of normal modes, out of which only one mode is in approximate dc synchronism with the beam and contributes to cumulative interaction. The RF current is computed from the equation of electron motion under the dc and RF fields. Combination of the circuit equation with the RF current equation leads to the solution of the propagation constants of the waves. This contains 6 roots 2 of them, being very far from synchronism, are not considered for the normal operation of this tube. The remaining 4 consist of 3 backward waves and 1 forward circuit wave of the 3 backward waves, 2 are recognized as being originated from the backward fast cyclotron wave, and 1 is from the backward circuit wave. Start-oscillation conditions can be calculated from a knowledge of these propagation constants.
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