The development of soft x-ray lasers in IAMS

An optical-field-ionization soft x-ray laser with prepulse-controlled nanoplasma expansion in a cluster gas jet was demonstrated. Pd-like xenon lasing at 41.8-nm with 95 nJ pulse energy and 5-mrad divergence was achieved, indicating near-saturation amplification. In addition, by using deflectometry of a longitudinal probe pulse to resolve the spatiotemporal distribution of the preformed plasma, we characterize and control the plasma density distribution near the target surface for the development of solid-target x-ray lasers. We show that the use of prepulses in an ignitor-heater scheme can increase the scale length of the preformed plasma and how the effect varies with target materials.