Direct-current photocathode ultrafast electron gun with immersed electrostatic lens

Abstract

The invention provides a rear-mounted direct-current photocathode ultrafast electronic gun with an immersed electrostatic lens. The rear-mounted direct-current photocathode ultrafast electronic gun comprises a cathode, an anode and an electrostatic lens electrode determined by an electric field and a particle simulation program, and a ceramic disc, a fine ceramic column, an electrostatic lens electrode ceramic support and an electron gun support which are suitable for rear mounting. and the cathode comprises a hollow cylinder, a circular top surface and an arc-shaped connecting surface. The anode comprises two smooth discs and a cylindrical protrusion on the back side, and a through hole is formed in the center of the anode. The electrostatic lens electrode comprises a circular top surface, a cylindrical side surface and an arc-shaped connecting surface, and a through hole is formed in the center. A cylindrical protrusion is arranged in the center of the circular top face, and the topannular face of the protrusion is chamfered. The electronic gun support is of a double-disc connecting structure, a top disc is connected with the fine ceramic column and the ceramic disc, the cathodeis fixed to the ceramic disc, and the anode is placed in a groove in the top disc. The electrostatic lens electrode is fixed on the ceramic support, and the ceramic support is fixed on a disc at thebottom of the support.

Description

technical field [0001] The invention belongs to the field of ultrafast electron diffraction, and in particular relates to a DC photocathode ultrafast electron gun with a submerged electrostatic lens and rear-mounted installation. Background technique [0002] In biology, chemistry, materials, information science, etc., the most critical primary mechanism often occurs at the molecular or sub-molecular structural level, and the time is often in the picosecond to femtosecond range, and the ultrafast detection of the picosecond to femtosecond process usually requires With the help of ultrashort-pulse lasers. Ultrafast electron diffraction (UED) is a technology that uses ultrashort pulse laser to achieve time-resolved pumping and detection. The principle is to use a spectroscopic device to divide the ultrashort pulse laser into two beams, one beam is used to excite the cathode of the electron gun to generate probe electrons, and the other beam induces the reaction area, and the ...

AI Technical Summary

Problems solved by technology

From the perspective of avoiding discharge, the farther the bracket is from the cathode, the better, but this will cause the electron gun to be too bulky

[0004] Due to the existence of electron space repulsion, the electron pulse of the probe will be broadened in the process of drifting to the sample, and the radial radius will increase, resulting in a decrease in the spatial resolution of the electron pulse.

The magnetic lens can focus the electron pulse, but it will cause the electrons in it to rotate perpendicular to the direction of propagation, resulting in a helical path, which is not conducive to the related applications of the "shadow method" and "schlieren method" in ultrafast electron diffraction technology

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