Teflon/silverstone? What’s that? In coal burning MagnetoHydroDynamics you have a superconducting field of E vector on say the y axis and M field on the x axis. It’s usually rectangular in cross section. The coal plasma comes thru on the z axis. The z axis plasma has to do WORK against the intense EM field lines, and just like some people you know, will do almost anything to avoid WORK.
Here that means coal slag slides sideways and piles up as gunk/slag on the throat walls, quickly gumming up the process. Also there is some radiation damage to the delicate, highly machined walls, actually a grid of nested buttons.
Yes, you could place 4 pads on the throat walls, but how fast would you have to replace them? But at least you’ve got the basic idea : protect the MHD walls from coal slag and radiation damage.
In thinking of the continuous 4 film-belts solution on waikiki beach 5 years ago, this solves the slag/radiation problem as well as keeping the walls cooler. The remaining problem, the CO2 coming out, could possibly be solved by shooting it thru a CaO(lime dust)chamber and thus getting CaCO3(limestone), nature’s way of storing CO2.
Anyway, as I envisioned it, the whole MHD package would fit inside a semitruck trailer and be moved around the coal field with mobile electric lines following along. A sort of muhammed coming to the mountain instead of transporting whole mountains of coal to muhammed.
Be as it may, imagine what it would mean to export electricity at 60%+ efficiency directly from the coal fields, and leaving only limestone blocks behind?
That's not gunk, that's DIAMOND COATING............