An Extended Theoretical Method Used for Design of Sheet Beam Electron Gun

An extended theoretical method based on Pierce theory is investigated in this paper to provide a reliably support and direct approaches for the design of the general sheet beam electron gun. First, the general characteristics of the sheet beam electron gun are discussed by dividing the gun into three investigation parts, and the design curves are derived theoretically, which are quite different from the curves for circular beam gun. The valid range of curvature radius ratio of cathode to anode R-c/R-a for sheet beam gun is achieved as 1.879 < R-c/R-a < 2.79 with the compression factor M of 1.879 < M < 30, which can make the sheet beam gun more stable and reliable. Then, the theoretical design method based on the design curves for sheet beam gun is deduced, and the reconstruction of anode aperture and the correction of cylindrical aberration are considered thoroughly, which may improve the design method more accurate and practical. Based on the theoretical calculation and parameters analysis, two types of sheet beam gun models with different M of 4 and 10 are constructed and simulated by the 3- D software, respectively, with the same beam voltage of 22 kV, a beam current of 3.50 A, and the beam cross section of 6 mmx0.24 mm. The results achieve the good agreement and verification with the theoretical expectation for the both the two sheet beam gun.