Comments on the page Maximum grid voltage of ion thruster got me wondering; what is the highest DC voltage ever intentionally produced by a spacecraft in space?
Photomultiplier tubes and micro-channel plates and charged particle spectrometers are common users of at least a few kV, but I suspect that there are some higher voltages out there somewhere.
10 kV? 100 kV? A megavolt?
"bonus points" for a high voltage that was intentionally produced in some way other than a conventional† DC power supply rated at that voltage. They don't need a Van de Graaff generator to make their hair stand out in microgravity, but perhaps someone snuck one up for fun?
†as opposed to unconventional, e.g. Van de Graaff, tether, balloon on cat, etc.