A device and method for evaluating photoelectron emission performance of photocathode materials

Abstract

The invention discloses an apparatus for evaluating the photoelectron emissivity of a photocathode material, and an evaluation method thereof. The evaluation apparatus includes a vacuum cavity, a vacuum pumping system, a vacuum degree measurement system, a photocathode assembly, a power supply system, an optoelectronic imaging system, a data acquisition system, a laser excitation system and a focusing mirror. The focusing mirror is arranged in the vacuum cavity, the focus of the focusing mirror is positioned on the surface of the photocathode material, the incidence position of a laser beam is adjusted to realize the continuous change of the incidence angle of laser and change the wavelength and polarization of the laser, and all parameters of the photoelectron emission characteristic can be obtained through in situ measurement. The method omits a series of tedious steps of frequent adjustment of the laser optical path outside the vacuum cavity in a discrete angle incidence laser excitation mode, can change the incidence angle only through changing the incidence position of the laser beam, and overcomes the discontinuous problem of angle caused by the discrete angle incidence.

Description

technical field [0001] The invention relates to performance evaluation of photocathode materials, in particular to a device for evaluating the photoelectron emission performance of photocathode materials and an evaluation method thereof. Background technique [0002] Photocathode material is a kind of material with photoelectric effect, which can produce photoelectron emission under laser beam excitation, mainly including copper, magnesium, niobium and other metals, gallium arsenide, gallium nitride and other semiconductors and antimony-cesium, cesium-tellurium, Sodium-potassium-antimony and other binary or multi-element alkali metals. The photoelectron emission properties of photocathode materials mainly include quantum efficiency, total emission beam current, angular distribution of emitted electrons, energy dispersion of electrons, brightness and thermal emittance, etc. [0003] The photocathode is one of the core components of photomultiplier tubes, electron accelerator...

AI Technical Summary

Problems solved by technology

[0005] However, since the photoelectron emission performance evaluation of photocathode materials needs to be carried out in ultra-high vacuum, controlling the continuous change of laser angle in ultra-high vacuum is a technical problem that has never been solved.

The existing technology for controlling the laser angle is limited to opening multiple light-transmitting flanges with different angles on the wall of the vacuum chamber, so the angle change of the incident light is limited and the angle values ​​are discrete values, so it cannot meet the needs of continuous different angles. Requirements for parameter measurement under laser incident angle

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