Laser-BNSiO2 Ceramics Interaction: simulation of the energy deposition on dielectric wall surfaces in Hall thrusters
Résumé
The dielectric wall surfaces of the annular chamber which are used in Hall Effect Thrusters (HET) to limit the plasma discharge play an important role but yet completely not understood and controlled. In order to investigate the effect of an energy flux on the wall we performed tests with a nanosecond pulsed laser to simulate the energy deposition on BNSiO2 (usual dielectric material for HETs). The tests have been carried out with the second harmonic (532 nm) of a Q-switched (10 ns) Nd:YAG laser focused on the samples placed in a vacuum chamber (10-6 Torr). The energy/pulse range explored has been 5 – 320 mJ, leading to fluences of 1 – 1000 J/cm2. The modifications induced by laser irradiation on the BNSiO2 targets have been analysed by profilometry and scanning electron microscopy. The plasma created by laser ablation has also been characterized by optical and spectral methods. The present paper presents preliminary results of these combined investigations.