pkbowen

Thank you for the pointer!

For anyone interested, the report by Polk et al. (1999) looks to have a good discussion of wear/failure mechanisms in long-term test thrusters. (Was hoping for something a little more metallurgy-oriented, but I'll keep poking around.)

Edit: Domonkos et al. (2001), "Investigation of Keeper Erosion in the NSTAR Ion Thruster" is interesting, but again, no mechanism or metallographic work.

Edit 2: A thesis by M. R. Nakles at VT has some information about wear by sputtering which is pretty interesting and has some very detailed modeling.

This sounds really interesting. Hate to be a bother, but do you think you could point us to any published work on this topic?

I am a PhD candidate in materials science, and mention of unexpected failure modes piqued my interest. Thought there might be something metallurgy-related, but nothing obvious to me so far from the top-cited NSTAR/NEXT reports.

Fun fact: one of the professors that recently retired from Michigan Tech had worked on iridium encapsulation of radioactive material for some of the early space probes. (i.e. "The effect of trace element additions on the grain boundary composition of Ir + 0.3 pct W alloys")