Calculation of Start-Oscillation-Current for Lossy Gyrotron Traveling-Wave Tube (Gyro-TWT) Using Linear Traveling-Wave Tube (TWT) Parameter Conversions

Author(s)
Heather H. Song

ABSTRACT

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.

Cite this paper

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.

H. Song, "Calculation of Start-Oscillation-Current for Lossy Gyrotron Traveling-Wave Tube (Gyro-TWT) Using Linear Traveling-Wave Tube (TWT) Parameter Conversions,"

References

[1] H. H. Song, D. B. McDermott, Y. Hirata, L. R. Barnett, C. W. Domier, H. L. Hsu, T. H. Chang, W. C. Tsai, K. R. Chu and N. C. Luhmann Jr., “Theory and Experiment of a 94 GHz Gyrotron Traveling-Wave Amplifier,” Physics of Plasmas, Vol. 11, No. 5, 2004, pp. 2935-2941. doi:10.1063/1.1690764

[2] Q. S. Wang, D. B. McDermott and N. C. Luhmann Jr., “Demonstration of Marginal Stability Theory by a 200kW Second-Harmonic Gyro-TWT Amplifier,” Physical Review Letters, Vol. 75, No. 23, 1995, pp. 4322-4355. doi:10.1103/PhysRevLett.75.4322

[3] C. S. Kou, Q. S. Wang, D. B. McDermott, A. T. Lin, K. R. Chu and N. C. Luhmann Jr., “High-Power Harmonic GyroTWT’s—Part I: Linear Theory and Oscillation Study,” IEEE Transactions on Plasma Science, Vol. 20, No. 3, 1992, pp. 155-162. doi:10.1109/27.142815

[4] Y. Y. Lau, K. R. Chu, L. R. Barnett and V. L. Granatstein, “Gyrotron Traveling Wave Amplifier: I. Analysis of Oscillations,” International Journal of Infrared and Millimeter Waves, Vol. 2, No. 3, 1981, pp. 373-393. doi:10.1007/BF01007408

[5] W. C. Tsai, T. H. Chang, N. C. Chen, K. R. Chu, H. H. Song and N. C. Luhmann Jr., “Absolute Instabilities in a High-Order-Mode Gyrotron Traveling-Wave-Amplifier,” Physical Review E, Vol. 70, No. 5, 2004, Article ID: 056402. doi:10.1103/PhysRevE.70.056402

[6] R. W. Grow and D. R. Gunderson, “Starting Conditions for Backward-Wave Oscillators with Large Loss and Large Space Charge,” IEEE Transactions on Electron Devices, Vol. 17, No. 12, 1970, pp. 1032-1039. doi:10.1109/T-ED.1970.17123

[7] M. Caplan, “The Gyrotron: An Application of the Relativistic Bunching of Electrons to the Generation of Intense Millimeter Microwave Radiation,” Ph.D. Thesis, University of California, Los Angeles, 1986.

[8] A. S. Gilmour, “Principles of Traveling Wave Tubes,” Artech House Inc., Norwood, 1994, pp. 273-305.

[1] H. H. Song, D. B. McDermott, Y. Hirata, L. R. Barnett, C. W. Domier, H. L. Hsu, T. H. Chang, W. C. Tsai, K. R. Chu and N. C. Luhmann Jr., “Theory and Experiment of a 94 GHz Gyrotron Traveling-Wave Amplifier,” Physics of Plasmas, Vol. 11, No. 5, 2004, pp. 2935-2941. doi:10.1063/1.1690764

[2] Q. S. Wang, D. B. McDermott and N. C. Luhmann Jr., “Demonstration of Marginal Stability Theory by a 200kW Second-Harmonic Gyro-TWT Amplifier,” Physical Review Letters, Vol. 75, No. 23, 1995, pp. 4322-4355. doi:10.1103/PhysRevLett.75.4322

[3] C. S. Kou, Q. S. Wang, D. B. McDermott, A. T. Lin, K. R. Chu and N. C. Luhmann Jr., “High-Power Harmonic GyroTWT’s—Part I: Linear Theory and Oscillation Study,” IEEE Transactions on Plasma Science, Vol. 20, No. 3, 1992, pp. 155-162. doi:10.1109/27.142815

[4] Y. Y. Lau, K. R. Chu, L. R. Barnett and V. L. Granatstein, “Gyrotron Traveling Wave Amplifier: I. Analysis of Oscillations,” International Journal of Infrared and Millimeter Waves, Vol. 2, No. 3, 1981, pp. 373-393. doi:10.1007/BF01007408

[5] W. C. Tsai, T. H. Chang, N. C. Chen, K. R. Chu, H. H. Song and N. C. Luhmann Jr., “Absolute Instabilities in a High-Order-Mode Gyrotron Traveling-Wave-Amplifier,” Physical Review E, Vol. 70, No. 5, 2004, Article ID: 056402. doi:10.1103/PhysRevE.70.056402

[6] R. W. Grow and D. R. Gunderson, “Starting Conditions for Backward-Wave Oscillators with Large Loss and Large Space Charge,” IEEE Transactions on Electron Devices, Vol. 17, No. 12, 1970, pp. 1032-1039. doi:10.1109/T-ED.1970.17123

[7] M. Caplan, “The Gyrotron: An Application of the Relativistic Bunching of Electrons to the Generation of Intense Millimeter Microwave Radiation,” Ph.D. Thesis, University of California, Los Angeles, 1986.

[8] A. S. Gilmour, “Principles of Traveling Wave Tubes,” Artech House Inc., Norwood, 1994, pp. 273-305.