Reply To: Site availability is poor

[bcreighton7]

bcreighton7 wrote: “The problem, we concluded, was that during each shot the inner layer of the steel, facing the plasma, was heated by the plasma to about 1000° C, enough to break up the chromium oxide in the stainless steel. Chromium oxide protects steel from further oxidation (rusting) at room temperature, but can’t withstand high temperatures, even for the few ms until the heat dissipated through the bulk of the steel.”

I assume an alloy like Hastelloy N has been rejected as not being as heat tolerant? Still with only 6-8% Chromium it should reduce the problem. Perhaps would accept a titanium coating better? I don’t know much about the properties of all the possible different alloys, but hastelloy N is a preferred choice for its resistance to oxidation at high temperatures.

Perhaps a relatively cheap solution would be a SiC coating? Higher melting point than SS. Doubt it could be done on site however. Would probably have to send in the chamber to be coated by a company like Electro-Coatings. They have a specialty coating they call Nye-Carb.

Then there is our friend CNT – perhaps it could be installed as a layer of conducting insulation to conduct heat away from problem areas. Don’t know how expensive that would be or if it would work better than a titanium coating – of course you need a place to conduct heat to.

P.S. If one of my suggestions is adopted, do I get a consultation fee? 🙂

For future reference my friend CNT is back in the news. It seems when utilized with nanophotonic crystals, they can convert 1000 C heat into light usable by photovoltaic cells. Perhaps covering some of the chamber walls with this material would be another way to use the excess heat to increase efficiency, while keeping critical components of the chamber cooler.
Here is a link: http://phys.org/news/2016-05-solar-usable-cell-efficiency.html