Effect of nozzle curvature on supersonic gas jets used in laser–plasma acceleration

Supersonic gas jets produced by converging–diverging nozzles are commonly used as targets for laser–plasma acceleration (LPA) experiments. A major point of interest these is the density at region interaction where laser ionizes plume to create a plasma, providing structure. Tuning profiles this crucial LPA optimization. “flat-top” profile desired line control propagation and high-energy electron acceleration, while short high-density often preferred lower-energy tightly focused interactions. particular design parameter curvature nozzle's diverging section. We examine three nozzle designs with different curvatures: concave “bell,” straight conical, convex “trumpet” nozzles. demonstrate that mm-scale axisymmetric that, distances from exit, significantly impacts shock formation resulting jet field and, therefore, an essential in design. show bell able produce regions higher densities. find trumpet nozzle, similar nozzles, can flat-top if optimized correctly flatter cost slightly wider edges. An optimization procedure derived compared process. present results computational fluid dynamics simulations performed program ANSYS Fluent verify them experimentally using neutral interferometry.