This looks a lot like something that the (assisted late) Gerald Bull would have built, except pointed downwards.
Another (and definitely doable) idea was to build a nuclear reactor in a titaninum/tungsten shell, that when activated would reach very, very high temperatures. Gravity alone would do the drilling through the molten rock. For obvious reasons, this was never built.
I’m fascinated by Gerald Bull and the concept of a nuclear powered tungsten shell boring through our mantle. Like rescuing the P-38 on the ice shelf using melting probes.