Mytec, may I add my thanks and also admiration to the collection of thanks that youve been offered here. Damn nice work in a field thats clearly black magic. Ive read this whole thread over the last few days and the fact that youre prepared to share your hard won experience with the board is very generous.

I did have a couple of questions too.

When I first read about autocascades on this board, I got the impression that they only worked properly at one specific load, and that if the load strayed from this (either higher or lower) the performance would drop off rapidley. But some of the things youve written seem to suggest that that is not true. Could you comment on that? For example, if this system you are now creating is tuned to do say 100w at -130C, what sort of temp would you expect at say 75w, 50w, 25w and 0w?

The other thing is that this thread has me wondering how low you can take this technique. Two things come to mind for me when I see this thread and contemplate following your design to make a copy - one is to act as a first stage for a stirling cooler, JT cooler or pulse tube cooler, with the aim of liquifying helium (I would consider this the holy grail of cooling no?), and the other is to make my own liquid nitrogen which would be useful for some of the vacuum work I like to do sometimes (electron tubes and vacuum stuff).

So how about going down to say -180C - I realise that you might not have done this before but in your opinion do you think its possible?

Thanks again for sharing so much information!

Pete