Several mission analyses have shown a need for higher power electric propulsion (EP) systems for both Earth orbit raising and deep space applications. Therefore, the development of high power EP systems is being emphasized as the necessary step towards possible future missions of large satellites.
Traditionally, xenon has always been the propellant of choice for EP applications due to the optimal compromise between performance and ease of handling. Although xenon has several technical advantages, its high price suffers of a remarkable fluctuation, posing serious budget concerns. To reduce propellant cost, a more economical alternative to xenon needs to be identified, while retaining thruster performance levels, without disregarding crucial system level considerations.
The KHT project plan focuses on an experimental campaign to test, with pure krypton and with different Kr-Xe blends, a 5 kW Hall-effect thruster, the Sitael-HT5k, designed to operate with xenon. Main objectives of the test campaign are: (i) characterisation of thruster performances and comparison with xenon as a benchmark; (ii) assessment of the erosion evolution of the channel walls; (iii) validation of a reduced order performance and erosion model; (iv) extrapolation of the effect of alternative propellants on lifetime and EOL performance; (v) assessment of system level implications related to the use of alternative propellants.
Figure 1 - Near field plume region of the Sitael-HT5k operating with different blends of Xe and Kr (Copyright: Sitael SpA)
Figure 2 – Reconstruction of the profile of Sitael HT5k outer ceramic wall starting from experimental data. Data have been collected at T0, after 30 hours of test with xenon and every ~30h test with a 75%Kr-25%Xe mixture. (Copyright: Sitael SpA).