Lifetime of Krypton thruster without shielding compared to Xenon - Starlink Satellites

Question

It is argued here (by the user uhoh) that Krypton might have a higher erosion rate on the thruster compared to Xenon. However, here is mentioned that the lifetime of Krypton-fueled thrusters might increase due to the fact that fewer doubly-ionized particles will occur (the 2nd ionization energy of Krypton is also higher than Xenon). Is there any concrete calculations on which one offers longer lifetime?

Expanding on the above, for Starlink satellites, where the mission lifetime is about 5 years, should lifetime limitations even be considered? Isn't this too little time to erode the thruster even with higher erosion rates than Xenon?

I couldn't find (and don't know how to calculate) how much time it would take for Krypton particles to erode the thruster to the point where it loses performance and becomes unusable.

Answer 1

It's very difficult to simulate the erosion rate of Hall thrusters and it is an ongoing topic of research. It depends on the geometry of the thruster, the materials, operating current and voltage, number of starts, etc. The best thing you can do is read about lifetime tests of previous Hall thrusters to get an idea of how long they last before they erode to a point of not being usable. However, I doubt Starlink's thrusters will reach that point, probably they will run out of propellant before.