Focal spot diagnostic of pulsed planar anticathode accelerator with compressed streak imaging.

Abstract

The spatial-temporal distribution of the focal spot is a key characteristic for evaluating a pulsed accelerator. However, the small number of frames and the low frame frequency limit the accurate analysis of the focal spot evolution process in a single shot. Compressed ultrafast photography (CUP) has recently demonstrated the ability of capturing 980 frames at 7 × 10¹³ fps with a single camera snapshot. In this paper, we demonstrate the utilization of compressed sensing for focal spot diagnostic of a pulsed planar anticathode accelerator called "Chenguang". In particular, our system incorporates a large-format streak camera, an ICCD camera and a PIN detector. The traditional pinhole imaging method is discarded for its low X-ray projection efficiency. Instead, a scintillator is placed close to the anticathode and converts the X-ray focal spot image to visible light image directly. Different reconstruction strategies, including the deep prior denoising algorithm, have been tried to verify the accuracy of the reconstruction results with each other. The two-dimensional time series images of the focal spot of "Chenguang" in strongly-pinched and weakly-pinched modes are observed for the first time. The detailed evolution process of the X-ray focal spot is revealed.