Question: What would the most complex tool you have tested???

Eleanor Holmes answered on 11 Nov 2013:

The most complicated tool I use is our cryostat. This is a big cylinder with a very complicated series of pipes inside. The reason it’s so complicated is that the cryostat is designed to get very, very cold. -272 degrees in fact. Also known as 1.6 Kelvin. Room temperature is about 300 Kelvin and The absolute coldest you can go is 0 Kelvin.

We achieve this sub-freezing temperature by circulating liquid Helium. Liquid Helium is the liquid form of the gas Helium which is one of the burning gasses in the stars. Liquid Helium is extremely cold but it still isn’t as cold as 1.6 Kelvin. So we have to use a special technique of expanding and contracting, evaporating and condensing. When you force a gas to take up more space than it wants to, it gets colder. So we manipulate this fact to get down to 1.6 Kelvin.

That would be fine if that’s all our cryostat did. We could get to 1.6 Kelvin and leave it there and go home and be happy. But we also have in that cylinder a superconducting magnet. That is a very strong magnet that only works at very low temperatures but which heats up while it’s turning on. So now our tool becomes a delicate balancing act. The whole thing has to be cold enough to turn the magnet on, but once you turn it on the whole thing heats up and if it get’s too hot the magnet will shut down. It’s very hard to use correctly and very complicated.