Mode Competition Effect on Frequency Locking of a Multimode Gyrotron by a Monochromatic External Signal

Design of master oscillator for frequency locking of a complex of megawatt level microwave sources

“…Preliminary calculations show that the locking regime is more favorable as compared with the regime of "free" generation for suppression of spurious modes, to realize operation point with highest efficiency (hard excitation regime zone), increase operating beam current and radiation power. 11,13 In the locking operation regime, voltage and current fluctuations in the high-power (megawatt level) gyrotron influence weekly the phase and radiation frequency. The frequency tuning of the external signal, at which the locking regime is retained, and the corresponding tuning of the radiation frequency, are several times wider than the width of the frequency tuning in a "free-running" gyrotron.…”

“…In such case, the order of operating mode grows up and the spectrum density of potentially excited modes within the cyclotron resonance band increases. This aggravates the problem of mode competition considerably and makes it difficult to reach the operating point, which corresponds to the regime of maximum gyrotron efficiency, at the “electron beam current – magnetic field of the solenoid” plane of parameters . Within this scenario, one can achieve selective excitation of the operating mode in the region of maximum efficiency values by using the method of oscillator frequency locking by an external highly stable source, which is well known in the oscillation theory .…”

“…Within this scenario, one can achieve selective excitation of the operating mode in the region of maximum efficiency values by using the method of oscillator frequency locking by an external highly stable source, which is well known in the oscillation theory . Recent theoretical works show that this approach makes it technically possible to increase the efficiency of megawatt devices by about 1.5 times.…”

“…Preliminary calculations show that the locking regime is more favorable as compared with the regime of “free” generation for suppression of spurious modes, to realize operation point with highest efficiency (hard excitation regime zone), increase operating beam current and radiation power . In the locking operation regime, voltage and current fluctuations in the high‐power (megawatt level) gyrotron influence weekly the phase and radiation frequency.…”

“…This aggravates the problem of mode competition considerably 10 and makes it difficult to reach the operating point, which corresponds to the regime of maximum gyrotron efficiency, at the "electron beam currentmagnetic field of the solenoid" plane of parameters. 11 Within this scenario, one can achieve selective excitation of the operating mode in the region of maximum efficiency values by using the method of oscillator frequency locking by an external highly stable source, which is well known in the oscillation theory. 12 Recent theoretical works 11,13 show that this approach makes it technically possible to increase the efficiency of megawatt devices by about 1.5 times.…”