Cryogen-free Magnetic Refrigeration

Hazard-free and user-friendly

Our devices are all-electrical and highly automatized. In particular they do not require rare and costly liquified gases (cryogens), but instead are using inexpensive solids as cooling media.

Excellent temperature precision and stability

Due to the direct magnetic control mechanism temperature set-points can be reached and held with extraordinary precision and long-term stability.

Minimal infrastructure and space requirements

Albeit offering cooling over an extremely wide temperature range magnetic cooling solutions can be built in a compact manner and have minimal infrastructure requirements.

Technology

Magnetic refrigeration is based on the magneto-caloric effect. When a medium is magnetized its magnetic moments get aligned and the heat of magnetization is released. Vice versa, if the medium is demagnetized its temperature drops. Cooling systems by kiutra can make use of two different types of magnetic refrigeration methods:

Adiabatic Demagnetization Refrigeration (ADR)

Adiabatic Demagnetization Refrigeration (ADR) is a well-established technique for the generation of cryogenic tem­peratures. As the temperature is controlled directly by applying a magnetic field to a solid-state magneto-caloric medium, the ADR principle offers excellent temperature stability.

In a conventional configuration employing a single ADR unit, demagnetization cryostats provide sub-Kelvin cooling for a limited amount of time. This so-called “hold time” is sufficiently long for various experiments and applications. How­ever, permanent cooling of the sample is impossible because the refrigerant must be regenerated in order to restart the ADR process.

Starting from an initial base temperature provided by a closed-cycle cryocooler (Step 1), a suitable cooling medium is first magnetized (Step 2). The heat of magnetization is then dissipated by the cryocooler (Step 3). Subsequently, the cooling medium is thermally decoupled by means of a so-called heat switch (Step 4) and then demagnetized afterwards (Step 5). During the demagnetization process the temperature of the cooling medium drops. If the set-point temperature is reached before the magnetic field, B, is lowered to zero the cooling power can be regulated to provide constant temperature over time, e.g. for several hours or even some days (Step 6). When the magnetic field is finally decreased to zero, the cooling process stops (Step 7) and the medium warms up to base temperature again (Step 8). The process can be restarted after some waiting time.

Continuous Adiabatic Demagnetization Refrigeration (cADR)

kiutra now offers the first commercial magnetic refrigerators for continuous sub-Kelvin cooling. We combine multiple ADR units which are interconnected and carefully balanced to implement continuous Adiabatic Demagnetization Refrigeration (cADR). In this technique, the final ADR unit, which is connected to the sample stage, can be regenerated while the sample temperature is kept constant by another ADR unit.

Further Information

kiutra offers a broad range of cryostats and accessories. Find the best solution to your specific cooling demands:

If you want to learn more about magnetic refrigeration and kiutra Cryostats, or discuss your specific cooling requirements, do not hesitate to contact our technical sales team. Our professionals are eager to discuss solutions with you!