Diagnosing plasma conditions in targets irradiated by intense light ion beams using K-alpha satellite line intensity ratios

The characteristics of K-alpha satellite line emission generated in intense light ion beam experiments is investigated. Inner-shell X-ray lines are em itted from moderate-temperature (T similar to 10(1)-10(2) eV) plasmas as 2p electrons of the target ions fill in K-shell vacancies created by beam ion -impact ionization. We focus, in particular, on the utilization of line int ensity ratios from He-like and Li-like: ions to diagnose target plasma temp eratures and densities. Although the K-alpha transitions for the He-like an d Li-like atomic systems are the same as those in laser-produced and Z-pinc h plasmas, the populating mechanisms for their upper states are completely different. That is, the upper states are populated from lower ionization st ages by ion-impact ionization, This enables diagnosis of plasmas in the 10- 100 eV temperature regime using the extensive instrumentation developed for X-ray crystal spectroscopy. Target plasma characteristics are simulated us ing a one-dimensional collisional-radiative equilibrium model in which atom ic level populations are computed by solving multilevel statistical equilib rium equations self-consistently with the radiation field and ion beam prop erties. We utilize atomic models which include for all ionization stages a detailed treatment of autoionization states which have K-shell vacancies. R esults are presented for Li beam-heated Al and Cl plasmas and proton beam-h eated Al plasmas. We find that, as in the case of laser-produced plasmas, t he He-like intercombination-to-resonance ratio provides a good density diag nostic. However, because the He-alpha line is produced in ion beam-heated p lasmas with a relatively low degree of ionization, it is less susceptible t o resonant self-absorption effects as compared to laser plasmas. In additio n, the Li-like satellite line structure is significantly different for plas mas heated by ion beams. Unlike laser-produced plasmas, the Li(dabc) and Li (qr) lines tend to be more intense than the Li(kj) lines. Because of this, we find the Li(dabc)-to-He-alpha ratio to be a good temperature diagnostic for intense light ion beam experiments. We also discuss the effects of beam -induced multiple ionization, photoionization, and resonant self-absorption on the line ratio diagnotics. (C) 1999 Elsevier Science Ltd. All rights re served.