Investigation of millimeter-wave band magnetron dispersion characteristics

Considered in this paper is the influence of electrode temperature on dispersion characteristics of millimeter-wave band magnetron. Cavity resonators without straps were used in millimeter-wave band magnetrons. In this case such systems have resonance equation as is shown below (1) Y-r + Y-n = 0, (1) where Y-r - cavity impedance, Y-n - interaction space impedance. The impedance of both interaction space and cavity has been defined in [1]. Dispersion characteristics of millimeter-wave band magnetron have been investigated. Calculation results are shown in Fig 1, 2. The electrodes investigation devices have changed geometrical dimensions by (2) for anode, high and width slot cavity and (3) for secondary cathode. R-z = R-z(1 + Delta t) (2) R-K = R-K .(1 + Delta t)/pi (3) where Delta - temperature expansion factor. This factor is different to anode and cathode. They have been determined separately. Dispersion characteristics of millimeter-wave band magnetron are presented in Fig 3, 4 for the case when temperature of both electrodes' is equal similar to 27 degrees C (curve 1), for the case when cathode and anode temperature is increased up to similar to 100 degrees C (curve 2) and for the case when anode temperature is increased up to similar to 100 degrees C, and cathode temperature is increased up to similar to 600 degrees C (curve 3). Using this method calculated accuracy has been achieved no more 5% compared with experimental results. Separation of magnetron oscillation were changed from 5 to 14% for different millimeter-wave band devices when the secondary cathode temperature has been changed from 27 degrees C to 250 degrees C.