[ufmace]

Another thing that occurred to me after watching some of their videos - how do they plan to control rate of penetration?

Their radiation head thing has to be a certain distance from the rock face it's cutting / vaporizing, but it isn't actually touching anything. So how do they know how fast they're actually vaporizing more hole and how fast to advance?

I'm sure you know this, but for the rest of the audience, conventional drilling rigs use the measured weight of the drillstring to determine how much weight is on the bit and how fast to advance. I don't see any good way for these guys to do anything like that.

[IshKebab]

Probably some radar or ultrasound distance sensor would suffice. Maybe even ToF of the laser.

I don't think that's anywhere near to the top of the issues they are going to run into.

[ufmace]

I do agree that it's probably nowhere near the top of the list of issues preventing this thing from working at least as well as conventional drilling technology.

However, anything about radar, ultrasound, or laser ToF would require electronics at the head of this waveguide and a way to communicate data to the surface. From what they're saying, the downhole environment of this thing is going to be very high temperature. Physically vaporizing 100% of the rock to make hole tends to do that. Conventional oilfield electronic tools already have trouble getting the MTBF above a few hundred hours at current downhole temperatures, which are much cooler. It seems likely that no electronics would survive at all at the temperatures they're planning on running.