Abstract
The potential for use of inner-shell vacancies produced by photoionization for creation of an x-ray laser is discussed. A detailed numerical model of the physical processes involved is described and applied to sulfur, one of the most favorable materials for production of x-ray lasing at energies substantially greater than 1 keV. At solid density an x-ray pumping power of 1.7×1016 W/cm2 is required with a rise time of less than 5 fsec, while at very low densities the rise-time requirement relaxes to about 50 fsec. The difficulties of meeting these requirements with current technology are discussed briefly.