Optical and electrical diagnostics in an iodine plasma
Résumé
Iodine is being studied as the next generation propellant for electric propulsion: dense, stored as a solid, it is also much cheaper than xenon for similar mass and ionization potential. Iodine plasmas are more complex and less studied than noble gases plasmas, leaving electric propulsion engineers with few models and diagnostics in their toolkits. Here we present three experimental diagnostics deployed on a low pressure Radio-Frequency inducted Inductively Coupled iodine plasma discharge. Two optical diagnostics are used to probe the I atom and the I2 molecule: classical absorption at 1.3 µm gives the line-of-sight integrated temperature and density of I; low-resolution broadband absorption spectroscopy between 480 and 500 nm gives the line-of-sight integrated density of I2. A Langmuir probe is used to determine the electron temperature and the negative species density at the centre of the plasma, provided that the data are treated by taking in consideration the electronegativity of the plasma. Comparisons with a global model derived from Grondein et al., 2016 tends to suggest that the recombination coefficient at the walls is underestimated for our setup.
Origine : Fichiers produits par l'(les) auteur(s)