When considering specifications for a cryostat, you will probably focus on size and operating temperature, but other criteria are just as important:
- Access to cryogens
- Frequency of use
- Physical location of the cryostat
Looking at these factors may cause you to consider using a cryogen-free refrigerator instead of a more traditional liquid cryogen system. While “cryo-free” systems have a higher initial cost, they may offer a lower lifetime cost of ownership with reduced operating costs. They may also be more convenient to operate than a liquid cryogen system. Most cryostat configurations can be designed to use refrigerators instead of liquid cryogens.
Access to Cryogens
If you don’t have access to a reliable supply of liquid cryogens, then cryogen-free refrigerators can provide the cooling solution using a compressor and heat exchanger to mechanically cool a multi-stage cold head down to cryogenic temperatures. In closed cycle systems the refrigerant gas is recirculated and never requires refilling. Access and cost of supplying power to the system is the only recurring cost associated with these systems.
Cost of Ownership
The initial cost of a cryogen-free refrigerator is higher, but if you plan on using the cryostat frequently, continuously or have heavy-duty cycles, then cryogen-free refrigerators will cost less over time. This is especially true for liquid helium temperatures. With cryo-free systems, there are no expensive cryogens to refill nor is there extra cost associated with transporting and refilling the cryogen. For remote locations or poorly accessible equipment, this is an important consideration.
Convenient and Continuous Hold Times
Depending on the location of the cryostat, it may simply be an expensive hassle to transport and refill cryogens. Cryogen-free refrigerators provide continuous unattended cold operation. Temperatures can be maintained for an indefinite period of time on most systems.
Ultra Low-Vibration Solutions
You will always have some vibration with a cryogen-free refrigerator. IRLabs has developed low-vibration couplings to ensure your instruments will reach the operating temperature while reducing the vibrations normally associated with cryogen-free refrigerators.
IRLabs supplies a wide range of cryogen-free refrigerators that provide cooling down to 0.3 K. Each of our systems can be highly customized to meet your application’s needs. Visit our cryogen-free refrigerator page to see detailed drawings and features.