Author(s)

Heather H. Song

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The 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.

Start-Oscillation-Current; Gyro-TWT; TWT; Lossy; Stable; Competing Mode

H. Song, "Calculation of Start-Oscillation-Current for Lossy Gyrotron Traveling-Wave Tube (Gyro-TWT) Using Linear Traveling-Wave Tube (TWT) Parameter Conversions," Journal of Electromagnetic Analysis and Applications, Vol. 5 No. 1, 2013, pp. 1-4. doi: 10.4236/jemaa.2013.51001.