Research On Adjustment And Testing Technologies Of Magnetron Frequency-locking And Phase-Locking Structure

As a compact and efficient microwave source device,magnetron has been used in many fields.In order to obtain higher output power,efficiency and array application,a microwave power source system which combines several magnetrons in some way can be considered.In this thesis,a 10-vane 2.45 GHz microwave oven magnetron is focused and study the design of frequency-and phase-locking structure of the magnetron,as well as the mechanism of mutual coupling locking between the two magnetrons.The design of the frequency-and phase-locking structure is based on a double-ridged waveguide impedance converter,and the frequency-locking of a single magnetron is compared with two injection methods.Simulations were also performed to analyze the effect of the locking structure connecting different positions of the cavity on the magnetron.It is concluded that the magnetron has the best performance（output power3.21k W,anode current 0.96A,electronic efficiency 79.65%）when it is connected to the cavity No.3 of the magnetron.In addition,the effect of different sizes of the locking structure on the working conditions of the magnetron is investigated.The gap width d has a strong influence on the output frequency and the extent of coupling to the locking structure side,while the size S,as well as the length of the structure,have a large impact on the output power P_o2at the coupling end.The former is positively correlated with P_o2,and the latter is negatively correlated with P_o2.The mutual coupling locking is studied for the two cases of identical and different magnetrons.If the two tubes are identical,the simulation results show that when the length of the structure l_g is 43mm,the frequency is locked at 2.450 GHz,the phase difference is locked to 0,but their output power is unbalanced.When l_g is set to 1/2 and the whole wavelength,namely 86mm and 172mm,the frequency of the two tubes is locked at 2.454 and 2.452GHz,and the phase difference is locked toπand 0.At this point,the output power of the two tubes is not different,the distribution is more balanced,and the overall efficiency of the system can be maintained at about 80%.In the presence of a frequency difference between the two magnetrons,it has been shown that a similar interlocking state can again be reached after adjusting l_g.Before and after interlocking,the output power of each magnetron is 4.47k W and the anode current is 1.52A,resulting in an efficiency of approximately 70%.After locking,the total output power of the two tubes can be close to 7k W,and the efficiency increases from 70%for a single tube to about 80%overall.Finally,a model based on interlocking two magnetrons has been studied to adjust the locking structure.A possible adjustment structure is given and verified by simulations.It is shown that the working conditions of the two magnons system can be adjusted by this adjustment structure.