Features of cryostats
When you need to rent or lease one of these devices for your lab, it is important to think about the temperatures you will need to cool your items to, as well as how often you will need to use the device. In some cases, you may find it easier to have more than one of these devices in the lab, particularly if you are working in a large setting with multiple people who may need to use the cryostat.
How cryostats work
The closed-cycle cryostats have cold helium vapor pumped through the central chamber. They have an external refrigeration device that will remove the warmed helium exhaust, which it will then cool, recycle, and reuse. These devices tend to use a substantial amount of electrical power, but they are convenient since you will not need to keep refilling them with helium. You can place items that need to be cooled onto the cold plate in the vacuum chamber.
Bath cryostats are filled with liquid helium. The cold plate is in contact with the helium bath, and then items can be put onto the bath to cool them down. With this option, you will eventually need to refill the liquid helium.
Continuous flow cryostats will use liquid nitrogen or liquid helium as a means of cooling. The cryogen will boil and is continually replenished to keep the temperatures cool and steady. The amount of time it will take to cool an object is dictated by the amount of cryogens available.
A multistage cryostat can offer temperatures that are even lower than liquid helium, all the way down to 1K in some cases. To do this, you will need to have an He-4 isotope container that you connect to a vacuum pump.
Some of the companies offering these types of devices include Thermo Scientific, Julabo, Stohr, Canberra, Baltic Scientific Instruments, and ASR.