Any metal in an incandescent crucible in a vacuum will emit metal vapors.
That has application in the electronics industry and depositing the in metallic films on plastic and glass surfaces as mirrors and sunglasses. The use as a propellant mass is an old idea going back to the 1930’s. One example was Ernst Stuhlinger cesium ion engine presented by Walt Disney. Actually hydrogen gas passing through a simple arc tops 10,000 seconds at a back pressure of 5 lb per square inch. Increasing the pressure melts the electrodes. That motor was in a science magazine when I was in the 8th grade Piner Jr High on Crocket St Sherman Texas. My Ac Ion motor has all these motors beat but to be taken seriously by NASA requires doctors degree in physics hanging on the wall. As I demonstrated, there is nothing to stop raising the AC sine wave voltage to one million volts or more. Unlike those other motors mine works both in the atmosphere and in space.
I decided to give more detail You see one mistake and it doesn’t work. One million volts is unforgiving. High voltage in a cage is like a tiger itching to pick a fight. Ionization should occur only at the syringe bundle exit nude metal exposure facing the glass coated grid. Two nude metal exposures of opposite polarity creates opposite ion polarities that travel in opposite directions in collision
with each other by pinch effect as their magnetic fields are additive. To prevent that the rebalser grid is glass coated.