<title>Applications and source development for high-repetition-rate x-ray lasers</title>

Abstract

Many applications in material science, chemistry, and atomic physics require an x-ray source that has a repetition rate of 1 Hz to a few kHz. In these fields, a very wide range of photon energies is of interest. One application is time-resolved surface photoelectron spectroscopy and microscopy where low energy (< 1{mu}J) pulses are required to avoid space charge effects but high-repetition rates ({approx} kHz) provide the high average power which is needed to obtain the desired resolution. In pump-probe experiments, it is desirable to have the repetition rate of the x-ray source be comparable to the repetition rate of the corresponding IR, optical, or UV laser. We show that the very high-repetition rate of synchrotrons (1--1000 MHz) results in an inefficient use of x rays for these types of experiments and that a kHz repetition rate x-ray laser would be an excellent source for many experiments. For some applications, a slower repetition rate of order 1 Hz is adequate provide the energy per pulse is larger ({approx}1 mJ). For example, in photoelectron spectroscopy of free clusters, an x-ray laser can provide the required large number of nearly monoenergetic photons during the short time the clusters can be probed inmore » each formation cycle. In the context of source development, we discuss conventional collisional x-ray laser schemes with mJ output pulses that can operate at Hz repetition rates using a high average power driving laser. The near term prospects for high-repetition rate x-ray lasing for photon energies below 100 eV are very good with higher energy capabilities expected in the future. In addition, prospects of table-top size x-ray lasers with kHz repetition rates are presented.« less