Demonstration of a high brightness injection-seeded soft x-ray laser amplifier using a dense plasma*

There is a great interest in the generation of high brightness beams of soft x-ray light. We have conducted a table-top experiment in which we have demonstrated the generation of an intense soft x-ray laser beam by saturated amplification of high harmonic seed pulses in a dense transient collisional soft x-ray laser plasma amplifier created by heating a solid titanium target. Amplification of the seed pulses in the 32.6 nm line of Ne-like Ti generates laser pulses of sub-picosecond duration that are measured to approach full spatial coherence. The peak spectral brightness is estimated to be $\sim $ 2$\times $10$^{26}$ photons/( s mm$^{2}$ mrad$^{2}$ 0.01{\%} bandwidth). The scheme is scalable to produce extremely bright lasers at very short wavelength with full temporal and spatial coherence for applications.