All the helium is contained in a welded metal structure so little leaks out. “We use about 60 grams of helium, or about 12 cubic feet at 60°F and atmospheric pressure, and it should last the 25-year life of the PowerDish,” says Talda.
From the above cited article.
If that is the case, that is actually not very much helium at all Less than one "jumbo" canister from Walmart or Target.
https://www.target.com/p/14-9-cu-ft-jum ... A-18808942
Considering the space inside the engine is largely taken up by the displacer, piston and generator windings, there is not really that much area left to fill.
Another thing I checked, as far as possible,..
A local machinist looking at the engine wanted to know if it was all stainless, or had to be.
I wasn't sure, but he said, he could probably make the engine parts, but stainless would be very expensive.
I knew from working in a scrap yard years ago that stainless steel is not attracted to a magnet. So I got a magnet to check.
Apparently the engine is mostly steel, ( not stainless ) as the magnet readily stuck to the casing, all but the heater end, which was not magnetic.
I had thought that a steel casing might cause some issue with the magnets in the linear generator, so I had assumed the engine was 100% stainless steel.
I did notice, however a bit of rust here and there.
Also in the photos of the engines exposed to the elements, at the Tooele army Depot there appears to be considerable rust on those engines
- Resize_20220817_162546_6661.jpg (142.59 KiB) Viewed 9294 times
Looks rather rusted to me anyway.
That is actually very good news IMO. The less expensive to manufacture the better.