How do Cryocoolers that use Helium as Coolant work?
A helium based cryocooler works just like an air conditioner, but helium is the gas rather than a halocarbon compound. The boiling point of helium is −268.928 °C, so such a cryocooler could get really cold. 

Helium is a rare gas and relatively expensive. So to cool a small experimental apparatus it is much cheaper to buy one helium based cryocooler rather than dewars and dewars of liquid helium.