Inline high flux

[Jonathan Schattke]

I'm working on a design for an inline high flux (> 1 MW) accelerator for a spallation neutron source.
Currently, I'm leaning toward a helicon/multiple RCH setup, along the lines of the VASIMR space engine, using hydrogen.
The advantage is no grids, so no wear parts. The disadvantage is the sloppy beam means it can't be used for much science.
Updates as I run the numbers.

[Doug Coulter]

I'm sure many of us here would be very happy to hear any reports of what works - it's what we're all about around this place - not the questions, the answers. What will you be ionizing?

What we found here is that even in my electrodeless microwave ECR ion source, chemical reduction of the walls (quartz) by deuterium ions was the limiting factor in source lifetime. We found that only pure alumina (very hard to get and handle) and boron nitride are immune from this, but also have lousy microwave characteristics. So we ran with the quartz, thinwall, and accepted that every couple hundred hours, we'd have to replace it, if not sooner. That's something you really don't want to have shatter right next to a turbo pump...kind of an expensive mistake to make.

[Jonathan Schattke]

I'll be generating the plasma in a magnetic bottle, so the MTBF should be higher (Ad Astra is shooting for years of service in space with VASIMR).
Hydrogen should give me the best end speed to input energy, and be cheap.