Efficient Carbon Cleaning of Soft X-ray Optical Elements at NSRRC

Abstract Carbon contamination on optics is observed at our soft X-ray beamlines. UV/ozone cleaning technique is used to eliminate the carbon contaminations at National Synchrotron Radiation Research Center (NSRRC). In the past, a mercury lamp was utilised as the light source of UV/ozone cleaning technique. Due to its larger divergence, the lamp must be placed close to the target optics. That is a time-consuming and high-risk task because of the tight space in the mirror chamber. Recently, two carbon cleaning systems were developed in NSRRC. The first one is to use an excimer laser as the light source and the second one is to use a deuterium lamp in conjunction with a collimator. The experimental results show that the former solution is more efficient than the latter. Besides, the process of carbon cleaning can be significantly simplified. The best cleaning rate of the excimer laser is 5.7 nm/hr at a distance of 1000 mm from the light source to the sample.