Soft X-ray spectra of low-Z gases produced by laser irradiation of a high-pressure supersonic gas jet

Abstract

Soft X-ray spectra have been obtained from laser-produced carbon, nitrogen, neon, and argon plasmas in the range between 50 and 500 eV. The plasmas were made by irradiating a high-pressure supersonic gas jet with 22-J, 3-ns pulses of 1.054- mu m laser light. This work is motivated by the recent success of recombination-pumped hydrogenlike carbon lasers at 182 AA (e.g., Suckewer et al., Phys. Rev. Lett., vol.55, p.1753, 1985). If sufficient laser energy can be coupled into the gas jet plasma, other low-Z elements such as nitrogen, oxygen, fluorine, and possibly neon could be stripped to the appropriate charge state and, presumably, laser. Because the laser energy needed to strip an atom depends sensitively on Z, these lower-Z ions are more accessible than higher-Z solid laser targets. In addition, X-ray lasing in lithiumlike ions could also be studied and would require even less laser energy. This low-Z sequence would supply a well defined set of X-ray lines which could be used for other scientific purposes. The spectra obtained show that hydrogenlike carbon and nitrogen are present in substantial abundance and that lithiumlike neon can be produced with the irradiation conditions used. >