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We discuss recent advances in high repetition rate table-top soft x-ray lasers that allow the generation of laser beams in the 25–100 eV photon energy region with peak spectral brightness that surpasses by several orders of magnitude that of undulators in third generation synchrotrons, enabling new applications. These advances include the demonstration of 5 Hz repetition rate table-top soft x-ray lasers that operate in the gain-saturation regime to produce intense beams at wavelengths ranging from 13.2 to 32.6 nm, and the observation of lasing at wavelengths down to 10.9 nm. The results were obtained by collisional electron impact excitation of highly ionized atoms in dense plasmas efficiently heated with picosecond optical laser pulses of only 1 J energy. Further improvement in the brightness of these compact sources was obtained seeding the soft x-ray amplifiers with high harmonic pulses. We have demonstrated the saturated amplification of high harmonic seed pulses in a dense transient collisional soft x-ray laser amplifier medium created by heating a solid titanium target. Amplification of the seed pulses in the 32.6 nm line of Ne-like Ti generated laser pulses of sub-picosecond duration that were measured to approach full spatial coherence. The scheme is scalable to produce extremely bright lasers at very short wavelength with full temporal and spatial coherence. These new compact lasers are allowing the implementation of a variety of table-top experiments with intense soft x-ray laser light. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We discuss very recent advances in high repetition rate soft x-ray lasers resulting from the use of two different types of hot dense plasmas: fast capillary discharges and laser-created plasmas. We have demonstrated a new high repetition rate 46.9 nm capillary discharge laser that fits onto the surface area of a small desk and that operates at a relatively low voltage, therefore not requiring a Marx generator. Laser pulses with an energy of ∼ 13 μJ are generated at repetition rates up to 12 Hz. About (2–3)×104 laser shots can be generated with a single capillary. This new type of portable laser is an easily accessible source of intense short wavelength laser light for applications. We also discuss the demonstration of 5 Hz repetition rate table-top soft x-ray lasers producing microwatt average powers at wavelengths ranging from 13.2 to 33 nm. The results were obtained by collisional electron excitation of Ni-like and Ne-like ions in plasmas efficiently heated with a picosecond optical laser pulse impinging at grazing incidence onto a pre-created plasma. Efficient deposition of the pump beam into the gain region allows for the excitation of soft x-ray lasers in this wavelength range with a short pulse pump energy of only 1 J. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]