American Institute of Physics, Review of Scientific Instruments, 11(93), p. 113537, 2022
DOI: 10.1063/5.0101885
Full text: Unavailable
The Pa α line (1875.13 nm) in the near-infrared (NIR) region was evaluated to apply Stark broadening of the line spectrum to the electron density measurement of the small-pellet ablation cloud in Heliotron J, a medium-sized helical-axis heliotron device. Pa α is three-to-four times broader than the visible H β line (486.13 nm) for the same electron density. Using a portable NIR spectrometer, preliminary proof-of-concept experiments determined the marginal density, below which the broadening was undetectable. The lower detection density limit can be decreased using a narrower entrance slit or a denser grating.