Analytical Theory of Multi-Stage Gyro-Amplifiers

submitted to IEEE ICOPS’99, June 20-24, 1999, Monterey, CA Analytical Theory of Multi-Stage Gyro-Amplifiers G.S. Nusinovich University of Maryland, College Park, Md 20742-3511 and B. Levush Naval Research Laboratory, Washington, DC 20375-5000 Nowadays there is an active development of high-power, largebandwidth, high-gain gyro-amplifiers for various applications. Design of such amplifiers is usually based on using numerous computer codes. Operation of amplifiers, however, depends on a large number of parameters. Therefore, a more or less complete optimization of all parameters requires a lot of computer time. A search in this multidimensional parameter space can be done much faster when some basic dependences of the device operation on parameters are known. Such dependences can be found when a simplified (semi-) analytical theory of the device is developed. In recent years there has been significant progress in the development of a simplified theory describing the operation of stagger-tuned, multi-cavity, single-beam and multi-beam gyroklystrons [1,2], gyrotwystrons with multi-stage prebunching [3,4] and two-stage gyro-traveling-wave-tubes [5]. In some cases the analytical approach was developed for describing not only the small-signal operation of the device but also the saturation effects occurring in the large-signal operation. In the present paper we plan to provide an overview of these theoretical studies, summarize the results, and discuss their applicability to real tubes. This work is sponsored by the Naval Research Laboratory and by the DoD MURI program on High Power Microwaves. [1] G. S. Nusinovich, B. G. Danly, and B. Levush, Phys. Plasmas 4, 469 (1997). [2] G. S. Nusinovich, B. Levush, and B. G. Danly,IEEE Trans. Plasma Sci. 26, 475 (1998). [3] G. S. Nusinovich, W. Chen, and V. K. Tripathi, IEEE Trans. Plasma Sci. 26, 468 (1998). [4] W. Chen, G. S. Nusinovich, and V. L. Granatstein, IEEE Trans. Plasma Sci. Special Issue on CRMs and Gyrotrons (to be published). [5] G. S. Nusinovich and M. Walter, “Linear Theory of a Two-Stage GyroTWT,” (Contributed papers at ICOPS-99).