If this microwave drill is vaporizing rock, how do they keep the vapor from re-condensing on the drill, wave guide, and shaft walls and eventually closing up the spaces between them causing things to get stuck?>
I imagine walls are an easier problem--just advance fast-enough compared to the deposition rate, and the thickening is controlled. Not sure about gradual buildup on the wave-guide, but some periodic cleaning mechanism (further back, away from rock-condensation) might be possible.
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> Even though the rocks are being vaporized, it does not mean that there is no material to be taken care of. “The gas will quickly recondense back to a very fine ash, which will then be taken up to surface by a purge gas. In our case, we will use nitrogen”, Matt [Houde] explains.
https://geoexpro.com/an-order-of-magnitude-more-energy-for-d...
> MIT’s Paul Woskov, whose research is the bedrock of Quaise’s approach, spent a decade proving out the physics involved. The system will use a beam of millimeter-wave energy—an electromagnetic frequency in the territory of microwaves—generated by a gyrotron on the surface. The microwave beam shoots down the drill hole alongside a gas—nitrogen, air, or argon—and evaporates layers of rock deep in the Earth. Then the gas binds and carries the vaporized rock back up to the surface like a plume of volcanic ash.
https://singularityhub.com/2022/02/14/startup-aims-to-drill-...