Probe for in situ measurement of work function in correlation with cesium dynamics suitable for ion source applications

This paper deals with the development of a vacuum compatible probe for in situ measurement (PRISM) of work function and cesium dynamics on a surface under ion source relevant vacuum conditions. The work function estimation is based on the measurement of the onset of the photoelectric signal after laser irradiation on the caesiated surface of the probe. Moreover, the PRISM is uniquely designed such that it can operate as a surface ionisation probe also for the measurement of cesium flux. In addition, cesium coverage on the same surface can be estimated using infrared imaging.