Plasma Diagnostics I

While laser Thomson scattering (LTS) is widely utilized for measuring electron number density and electron temperature in high- and low-temperature plasmas, its potential to probe ion properties has remained largely untapped. This contribution presents a methodological advancement: we show that Doppler-shifted laser light scattered off ions can be directly observed in laser-produced plasmas operating in “intermediate” regimes between low temperature and inertial confinement plasmas. This requires concomitant high-spectral resolution measurements and plasma conditions where ions are sufficiently energetic to produce a spectral shift discernible from the dominant Rayleigh scattering signal at the laser central wavelength. We successfully demonstrate this capability in laser-produced plasmas on a moving tin wire target, investigating the impact of different background gas environments. This extends the utility of Thomson scattering, offering a powerful tool for comprehensive plasma characterization.

Funding acknowledgement

We gratefully acknowledge financial support of the U.S. Department of Energy, Office of Fusion Energy Sciences under award number DE-SC0025627. We also acknowledge the financial support of the College of Science and Engineering and the Department of Mechanical Engineering of the University of Minnesota, Twin Cities.