Steam Distilling vs "Thumper"

[squigglefunk]

what is the difference?

If I fill the "steam generator" with water or cleared mash to heat the still?

Its seems like basically the same thing to me but in the case of the mash heated mash you would water the booze down less?

So, I guess is the main point to my ramblings here is: can I just fill the "steam generator" with clear mash? Or is it better to just use water?

and if so, any problem if my still that I'm heating is a bit bigger than the "steam generator"

How can I know how much liquid I need to run a full run without running out of "steam"

as per my usual, thanks for your knowledge and the great place we got here