Design and characterization of supersonic nozzles for wide focus laser-plasma interactions.

In this work we optimize the contour of supersonic nozzles to produce long and stable gas jets suitable to be used in loose focus laser-plasma applications. The nozzle design method takes into account the inclusion of a boundary layer that increases the length of the usable gas jet. Two 8 mm supersonic nozzles were characterized, one with a Mach number of 3 and another with a Mach number of 6, using a Mach-Zehnder interferometer performed with a He:Ne 4 cm expanded laser beam. The experimental results confirm that the inclusion of the boundary layer produces an 8 mm constant longitudinal density profile for the nozzle with a Mach number of 6 (NM6) and a 4.5 mm constant longitudinal density profile for the nozzle with a Mach number of 3 (NM3).