So there is this great movie that you should totally go see, it is about an eccentric scientist who befriends a simple-minded neighborhood teenager and sends him backwards in time in a car converted into a time machine…
Something like this just happened in our lab. We started out a couple of years ago as a cryogen-free operation. Instead of relying of liquid helium, we used closed-cycle cryostats where helium circulates between a compressor and a cryostat and extracts heat from a vacuum-shielded volume. There are two reasons why cryogen-free systems are great – they save money on (pricey) liquid helium and they are easy to operate at a push of a button.
But in the meantime our generous university set up a helium liquefier, which supplies nearly-free liquid helium to us. And so now we built our first liquid helium setup – a dunker stick! It derives its name from a concept of dunking your specimen into liquid helium in order to reach a low temperature of 4.2 Kelvin, at which helium is stored in liquid form.
From the technological point of view, it is a step back compared to our cryofree setups. But we can use it for many quick measurements and tests, which is great.