A bit hidden here is the tech they’re using - vacuum tubes! Gyrotrons. There’s still a few hair-raising applications remaining for this lovely technology for which there are no solid state alternatives: Ultra fast high energy switching (krystrons - used in nuclear weapon triggers among other things) and now, it turns out, burrowing Morlock holes a dozen miles through the earth’s crust.
A bit hidden here is the tech they’re using - vacuum tubes! Gyrotrons. There’s still a few hair-raising applications remaining for this lovely technology for which there are no solid state alternatives: Ultra fast high energy switching (krystrons - used in nuclear weapon triggers among other things) and now, it turns out, burrowing Morlock holes a dozen miles through the earth’s crust.