start-oscillation-current of a gyro-TWT (gyrotron traveling-wave tube)
determines the stable operating current level of the device. The amplifier is
susceptible to oscillations when the operating current level is higher than the
start-oscillation current. There are several ways of calculating the
start-oscillation current, including using the linear and nonlinear theory of a
gyro-TWT. In this paper, a simple way of determining the start-oscillation
current of lossy gyro-TWT is introduced. The linear TWT parameters that include
the effects of synchronism, loss, and gain, were converted to gyro-TWT
parameters to calculate the start-oscillation-current. The dependence on
magnetic field, loss, and beam alpha was investigated. Calculations were
carried out for a V-band gyro-TWT for both operating and competing modes. The
proposed method of calculating the start-oscillation current provides a simple
and fast way to estimate the oscillation conditions and can be used for the
design process of a gyro-TWT.
Cite this paper
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