Plasma diagnostics using high-resolution spectroscopic techniques*†

Abstract

Density-sensitive line intensity ratios measurable in high-resolution spectra are discussed for high-temperature plasmas (1.5–1300 eV). By working along isoelectronic sequences, it is possible to find density-sensitive ratios over a wide range of electron densities (1012 to ∼1021 cm−3). This range includes the density of a number of laboratory plasmas of current interest. We also discuss the temperature sensitivity of some of the line ratios for ions formed in the colder plasmas with temperatures of 1.5–15 eV. We present a table of forbidden lines obtained from Skylab spectra of the solar corona. Lines of this type should be detectable in certain laboratory spectra. Their long wavelengths make these lines particularly suitable for measuring the ion temperature or nonthermal motions. Finally, we show the feasibility of detecting megagauss magnetic fields in high-temperature plasmas, from profiles of selected spectral lines.