  Shocks in supersonic flows offer both a high-density and sharp density
gradients that can be used, for instance,for gradient injection in laser-plasma
accelerators. We report on a parametric study of oblique shocks created by
inserting a straight axisymmetric section at the end of a supersonic "de Laval"
nozzle. The impact of different parameters such as throat diameter and straight
section length is studied through computational fluid dynamics (CFD)
simulations. Experimental characterizations of a shocked nozzle are compared to
CFD simulations and found to be in good agreement. We then introduce a newly
designed asymmetric shocked gas jet, where the straight section is only present
on one lateral side of the nozzle, thus providing a gas profile that can be
used for density transition injection. In this case, full-3D fluid simulations
and experimental measurements are compared and show excellent agreement.
