I'm not sure about what's used in all industry applications, but this video explains one implementation of a super-cooling setup: https://www.youtube.com/watch?

I'm not sure about what's used in all industry applications, but this video explains one implementation of a super-cooling setup: https://www.youtube.com/watch?v=7jT5rbE69ho https://www.youtube.com/watch?v=7jT5rbE69ho. I won't even try to summarise it - I'm sure I'd get it wrong! Fascinating stuff though.