Design of Phase Correction Mirror System Based on Gaussian Field Propagation Theory

Gaussian field is a very important spatial distribution form of electromagnetic field. Gaussian field has a narrow beam in space, and the field intensity has a finite width distribution in space, which makes the Gaussian field can be used in gyrotron output structure. In this paper, some propagation characteristics of Gaussian field are analyzed, including beam waist radius, divergence angle, wavefront and curvature radius of wavefront. Based on the Gaussian field propagation theory, the phase correction of five Gaussian fields with different parameters is studied in this paper. A numerical model including two phase correction mirrors is established to correct the phase of incident field. The purpose of thses mirrors is to eliminate the astigmatism and ellipticity of the incident Gaussian field, compensate the phase of the Gaussian field on the correction mirror, and obtain the ideal Gaussian beam on the ouput window. After correcting, the vector correlation coefficient between the output Gaussian field and the ideal Gaussian beams are above 99.1%.