Based on CHIPIC platform and the ionization physics mechanism between electron and gas, a full three-dimensional particle-in-cell/Monte Carlo (PIC/MCC) code is developed with the MCC ionized collision module. The simulations of a relativistic backward wave oscillator with helium gas are used to verify the code. The results show that the gas can enhance the current, peak power and pulse length, but too much gas leads to the reductions of peak power and pulse length.

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Two models (Ta and Nanbu) of Coulomb collisions are compared theoretically, and the difference in scatter angle between Ta model and Nanbu model is analyzed particularly. The model of Coulomb collisions between electrons in the code which is developed already with Ta model is rebuilded with Nanbu model. Then, the codes with Ta model and Nanbu model are used for simulating electron energy distribution in JAEA 10 A respectively. The results of simulation are compared with the experimental results, showing that the electron energy distribution is closer to Maxwell distribution with Coulomb collisions and the Nanbu model is more accurate than the Ta model.

In order to break the limitation of gyrotron emission producing the ideal electron beam in the traditional gyrotron numerical simulation, this paper on the basis of theoretical analysis of structural parameters for the 94 GHz double-anode magnetron injection electron gun, by optimizing the grid plot of conformal FDTD algorithm, obtains the high-performance electron beam of the horizontal and vertical velocity ratio of 1.42 and the maximum velocity spread of 5.92%, By using the optimized electron gun to replace the traditional gy rotron emission in the numerical simulation of the gyrotron system and using the four-process parallel MPI in computation, we finally obtain a TE03 mode, 94 GHz, the average output power of about 40 kW, with on efficiency of 10.5% for the high-performance gyrotron oscillating tube.

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