Wave Mode Actuator Theoretical And Experimental Study

At present, there are two ways, radial output and horizontal output, in the gyrotron. Mode converters are currently used to convert the interaction mode, which is usually a high order gallery mode (TEmn, TMmn, m>>1, n-1,2), into the Gauss mode in compact systems like in-vehicle system. If not caught early, errors in design and processing of the mode converter are costly. Consequently, in order to provide the source of cold test, mode generator is needed to generate these high order modes. In this case, the theoretical and experimental study is done in the paper.There are two main methods of designing mode generator, one is perturbation of radius or axis in waveguide, through which mode conversion is achieved; the other is quasi-optical conversion. Since recent gyrotrons are operated in high-order TE mode, the generator based on the perturbation of radius or axis in waveguide will be very long and have undesirable modes, which is not convenient. Based on theoretical equation and boundary conditions, three-section coaxial cavity which generates TE62 mode is designed with program in Matlab. With the simulation of HFSS, coaxial TE62 mode is got. On the basis of this, three TE62 mode generators of circular waveguide are designed, that is, mode converter of rectangular waveguide TE10-circular waveguide TE62, TE62 mode generator based on the theory of partial wave and quasi-optical TE62 mode generator. Meanwhile, each model is simulated and optimized in FEKO, and mode purity is also analyzed with program in Matlab. The TE62 mode purity obtained with the above three generators is 90.05%,93.22%and 96.1%, respectively. Obviously, the purity of TE62 obtained by quasi-optical TE62 mode generator is quite high, meeting the practical requirements.The experimental study for 3mm bandwidth quasi-optical mode generator is carried out. This experiment is done with the existing testing system. Experimental data is kept in the computer and analyzed after the experiment, at the same time, the power distribution of the beam is also given. The experiment show that the testing result is consistent with theory.