Photopumped Balmer β X-ray lasers

Abstract

ABSTRACT A new x-ray laser scheme is proposed that lases on Balmer j3 transitions from 2.87 nmto 5.99 nm in H-like ions and is resonantly photopumped by Ly y radiation from the same kind of H-like ions. Optimisation designing for targets and driving laser conditions is carried out using simulation codes. A recombining plasma producedfrom a slab target irradiated by a 50 ps driver pulse is found to be the ideal pumpplasma to provide maximum Ly y line radiation. Numerical calculations predict thatthe high gain coefficients on Balmer 3 transitions of H-like ions with atomic number z = 9 to 13 can potentially be achieved with this scheme. 1. INTRODUCTION Intensive efforts have been made in a world-wide range to produce an x-ray laser within the water-window since the amplification in soft x-ray region was demonstrated by collisional excitation and recombination schemes.'3 More recently,the first demonstration of x-ray lasing has been reported in the water window while gain saturation has been reached at about 20 nm using the Ni-like collisional