Shock wave velocity diagnostics plays a crucial role in multiple fields, including high energy density physics and inertial confinement fusion. The planarity of two-dimensional velocity fields not only carries information about the driver source uniformity but also reflects the microscopic inhomogeneity within the carrier material structure. Therefore, two-dimensional quasi-continuous diagnosis of velocity fields is of significant importance. Currently, the most mature technology is one-dimensional line VISAR; however, the lack of spatial directional information prevents it from measuring wavefront planarity. Traditional two-dimensional VISAR employs gated CCD for recording, which is limited by its working principle to achieve only single-frame imaging, making continuous wavefront measurement impossible and failing to meet experimental requirements. Our team has proposed a CUP-VISAR technology based on Compressed Ultrafast Photography (CUP), capable of capturing the temporal evolution of two-dimensional velocity fields. In previous work, we completed the validation of the overall technical route through dynamic experiments, successfully integrated the ultrafast compression module with the Any-Reflecting-Surface Velocity Interferometer, obtained encoded compressed fringe patterns, and decoded up to 32 frames of time-resolved interference images.
This year, we completed the development and upgrade of the complete instrument hardware and software, including the compressed imaging optical path hardware, probe laser, streak camera, and data processing algorithms. Multi-frame high-temporal-resolution CUP-VISAR experiments were conducted on the Shenguang 10KJ laser facility to verify the overall instrument performance. We obtained shock wave two-dimensional velocity field diagnostic data with a maximum temporal resolution of 2 ps and up to 55 frames. The one-dimensional fringe evolution history extracted from CUP-VISAR results shows a velocity error of less than 2% compared with the corresponding diagnostic region of one-dimensional VISAR.
 

Shock wave diagnostics, Compressed ultrafast imaging (CUP), Two-dimensional shock wave velocity field