Development of a high-spatial-resolution schlieren measurement system for observing shock waves in laser wakefield accelerator target

Laser wakefield acceleration is promising for compact electron acceleration by offering an ultra-high electric field. However, producing stable, high-quality electron beams remains challenging, particularly in the shock-injection regime where most of the instabilities arise during the injection stage. This indicates a strong sensitivity of beam quality to the shock front structure and its position relative to the laser focal position. A Schlieren imaging system is developed with ∼1μm spatial resolution to directly visualize the shock structure and quantify its position stability. By reducing the fluctuation of the shock position from 9.9 to 4.3 μm, the electron beam pointing stability has been improved by an order of magnitude.