多碱阴极光电发射机理研究

通过比较有Cs-Sb表面层多碱阴极和未有Cs-Sb表面层多碱阴极的荧光谱,发现有Cs-Sb表面层多碱阴极的荧光谱峰值波长向短波方向“蓝移”以及荧光峰增强的现象.这一现象表明在多碱阴极Na2KSb基层上制作Cs-Sb表面层之后,不仅多碱阴极的逸出功降低,而且 Na2KSb基层的结构也发生了变化.这意味着在相同功率和相同频率入射光照射下,经过表面Cs-Sb处理的Na2KSb基层能够产生更多的跃迁电子并且跃迁能级更高,逸出表面的机率更大,获得的阴极灵敏度更高.这表明Cs-Sb表面层既具有表面效应,又具有体效应.要进一步提高多碱阴极的灵敏度,除进一步降低多碱阴极的逸出功外,还需进一步提高Na2KSb基层的性能,使相同功率和频率的入射光能产生更多的跃迁电子,并且跃迁的能级更高,这就需要进一步改进工艺,提高Na2KSb材料的性能.

Photoemission Mechanism of Multi-alkali Cathode

Fluorescent spectra between multi-alkali cathode with Cs-Sb surface layer and without Cs-Sb surface layer were compared.It was found that phenomena of peak wavelength of the fluorescent spectrum shifted to shorter wavelength and intensity of fluorescent spectrum became stronger for the multi- alkali cathode with Cs-Sb surface layer.This phenomenon shows that in the condition of a multi-alkali cathode with Cs-Sb surface layer,the surface work function of multi-alkali cathode is reduced,and Na2KSb structure is changed.This means that in the conditions of the same frequencies and the same incident power irradiation,Na2KSb with Cs-Sb surface layer can be excited more transition electrons and obtain higher transition energy levels.So they are able to escape the multi- alkali cathode surface more easily and have higher probability to access the vacuum .This will lead to higher cathode sensitivity and shows that the Cs-Sb surface layer has a surface effect and physical effects.To further increase the sensitivity of multi-alkali cathode,it is needs to improve the performance of Na2KSb layer in addition to further reduce surface work function of the multi-alkali cathode,so that the same power and frequency of incident light can produce more transition electrons and higher energy transition levels,which needs to further process improvements to make Na2KSb material better.