Narrow band X-ray emission in the water-window spectral region from a laser heated gold copper mix-<Emphasis Type="Italic">Z</Emphasis> plasma

A laser plasma X-ray source of narrow spectral range in the water-window region, is reported using a 50–50 (atomic fraction) mixture of gold-copper mix-Z planar target. Plasma was produced using the second harmonic beam of an Nd:glass laser focused to an intensity ～10¹³ W/cm² on the target. The spectrum of the plasma radiation transmitted through a free-standing 0.4 μm aluminium/0.9 μm vanadium X-ray filter foil was measured to lie in the narrow-band of 24–26 Å. This provides a debris-free X-ray dose of 2–3 mJ/sr which can be used for single shot X-ray imaging of live biological samples.