Abstract

The recently reported saturation¹ of the 109-nm Auger laser in xenon III² utilized a newly developed, oblique incidence, traveling-wave laser-produced plasma geometry. This geometry allows excitation of a variable gain length while maintaining constant pump laser intensity on target and soft x-ray conversion efficiency. Distribution of the soft x-ray pump flux over an increased length is desirable in photoionization-pumped lasers because of the pump flux, density, and gain limitations imposed by the free electrons created in the pumping process. The assumption that the gain will be highest at some optimum pump flux leads to simple scaling laws for the total small signal gain and transverse dimensions of the laser as its length is changed. The gain per unit pump energy, the brightness of the output beam, and the Fresnel number of the laser should all improve with increased length. We discuss experiments to verify these scaling laws, where we increase the length of the laser simply by increasing the angle of incidence of the pump beam. In addition, we expect to discuss the effects of varying intensity, wave-length, pulse length, and a prepulse on soft x-ray conversion efficiency and laser operation. These studies lead to a better understanding of the factors important in the design of useful photoionization lasers.

© 1988 Optical Society of America