With the advent of high-intensity, subpicosecond laser systems, great progress has been made in the development of ultrafast x-ray sources, ranging from the ultraviolet (XUV) to the hard x-ray spectral region. High-order harmonic generation (HHG), using high-energy, femtosecond laser pulses, has proved to be a convenient way of generating coherent radiation in the soft-x-ray and ultraviolet spectral region. Recently, x-ray sources based on emission from high-density, laser-produced plasma's have been reported. These x-rays are incoherent but have high brightness as a result of the small size, short lifetime and high temperature of the radiating plasma.

H.G. Muller , H.G. Muller , M.V. Fedorov

Constantinescu, R. C., Muller, H. G., Muller, H. G., Schins, J. M., Breger, P., Agostini, P., … Mysyrowicz, A. (1996). A collinear setup for optical/x-ray cross correlation measurements based on laser-assisted Auger decay. In H. G. Muller, H. G. Muller, & M. V. Fedorov (Eds.), Super-Intense Laser-Atom Physics IV : Proceedings of the NATO Advanced Research Workshop on Super-Intense Laser-Atom Physics (SILAP IV), Moscow, Russia, August 5-9, 1995 (pp. 371–380).