Laser induced fluorescence of singly ionized atomic iodine: Measurements in the plasma source of an electric propulsion device
Phys. Rev. E 114, 035201 – Published 1 September, 2026
DOI: https://doi.org/10.1103/jmh3-hwd8
Abstract
A laser induced fluorescence (LIF) scheme is investigated to probe singly ionized iodine ions () in electric propulsion devices. The transition at 516.261 nm is considered and the theoretical computation of the weights and positions of the hyperfine structure is carried out. First, the measurement of the fluorescence signal is performed in the ionization chamber of an rf gridded ion engine, the PEGASES thruster, demonstrating that the chosen LIF scheme is well suited for the study of electric propulsion devices operating with iodine. Second, spatial measurements of the temperature, velocity, and density are taken in this plasma source for several conditions of iodine pressure from 0.5 to 10 mTorr. First, an increase of the temperature of the ionic excited population close to the antenna is observed. Second, the analysis of the Doppler shift of the LIF profile shows the acceleration of the ions in the source. Third, the comparison of the measured LIF profiles with previous measurements shows that the density of the probed lower excited state is proportional to that of the ground state in the conditions of the experiment.
