Smith-purcell, Effects In Photonic Crystal Particle Simulation

Smith-Purcell free electron laser is a very important branch of free electron laser. This paper thoroughly analyzes the Smith-Purcell effect of photonic crystal, the defect location relationship between free electron and photonic crystal, the defect size optimization of photonic crystal and the emitter parameter of the free electron emitted by the emitting electrode, thus comes to some research achievements with great reference value through imitation in the established model.Based on Smith-Purcell free-electron laser theory, this paper firstly discusses the features of a new type of free electron laser, especial the Smith-Purcell effect of photonic crystal, then it comprehensively studies the Smith-Purcell radiation of photonic crystal with defects through the particle simulation method. It further studies the free electron lasers with trihedral reflectors separately made up of photonic crystal and spherical mirror and plane mirror. The 20 x 7 photonic crystal is studied according to the particle simulation method. It discusses the influences of photonic crystals, with defects respectively on the surface, at the bottom and in the interior, on Smith-Purcell radiation. The research shows that (a) when electron flies over the surface of photonic crystal and produces Smith-Purcell radiation, the influences of defects at different locations on the same layer with the same size change regularly, which means the frequency output of the crystal gradually increases when it moves away from the electron emitting point, but the output frequency is always smaller than the output frequency of the crystal with defects is always less than that of crystal with complete structure; (b) the influences of defects at the same position on different layers with the same size change irregularly, and the defect at some certain positions make the output frequency increase; (c) with the defects on the surface of the photonic crystal enlarged and deepened, the consistency of the Bz equipotential line gradually lowers and the intensity of radiation gradually decreases; (e) with the defects on the surface of the photonic crystal enlarged and deepened, the output frequency gradually increases, which is opposite to the situation when the defect is on the surface. Thus we can try to obtain larger output frequency through making larger defect in the photonic crystal. The peak power, the frequency output and average power output of the spherical mirror trihedral reflector set with different output angles is measured with the particle simulation method. According to the research, supposing the output angle is 45 degree, the peak power becomes stable within 20ns under the selected parameter condition; the average power output graph is well-distributed, which means that said peak power output is the best one within three kinds of angles.Besides, this paper further discusses the condition of plane mirror trihedral reflector under the same assumption. It shows that the peak power becomes stable within 20ns when the output angle is 60 degree; the average power output graph is well-distributed, which means that said peak power output is the best one within three kinds of angles.Comparing those two results, the plane mirror trihedral reflector is slightly better than the spherical mirror trihedral reflector separately on the aspects of the peak power, the frequency output and average power output.