Optimisation of a laser-plasma soft X-ray source excited in a pulsed xenon jet

A 'clean' (debris-free) pulsed soft X-ray (12.5–25 nm) source excited by nanosecond neodymium laser pulses in a pulsed xenon jet was optimised. The source efficiency in the λ < 15 nm range is improved due to the weakening of photoabsorption in the peripheral regions of the gas jet in going over to the supersonic regime of xenon gas flow into vacuum, as well as due to the laser beam focusing onto the plateau edge in the radial gas density profile nearest to the observer. The source efficiency at 13.5 nm is 0.22% into a solid angle of 2π sr into a 0.5 nm band.