Cyclotron wave amplifiers at microwave and millimeter wave frequencies

Summary form only given, as follows. Cyclotron wave parametric, and cyclotron wave electrostatic amplifiers were developed in Russia and the United States in the late 50´s and early 50´s. The application was for input amplifiers in the receivers of radar and communication systems. While work in the west was abandoned in favor of solid state, it continued in Russia; these are important components of many Russian military and civilian systems. Advantages include low noise temperature, high degree of linearity, receiver protection and very fast recovery time after a microwave overload. The basis of the device is the parametric amplification of the fast cyclotron wave on an electron beam. The beam is cooled in one of two ways to achieve low noise temperature. Recently, a summary of the theory and behavior of these devices have appeared in the United States. They have been developed only at microwave frequencies as high as 35 GHz. To go to higher frequencies means still higher magnetic fields, which is difficult to do with permanent magnets. An alternative is to operate at harmonics of the cyclotron frequency. The theory of cyclotron wave amplifiers at harmonics of the cyclotron frequency has recently been worked out.