Research applications, cooling of cavities or superconducting magnets require hundreds of watts refrigeration capacity at liquid helium temperature.
For these applications Linde Kryotechnik has developed refrigeration systems on the basis of the L-series standard units with an available refrigerating capacities from 100* to 900 W at 4.5 K. The wide range of performance ratings is achieved by different compressors and precooling with or without liquid nitrogen. Refrigeration below 4.5 K requires cold ejectors or cold compressors to reduce the pressure in the experiments. Adsorbers are integrated into the cold box at 80 and 20 K to remove any residual contaminants from the helium. Like the standard liquefaction systems, the refrigerator is fitted with a Siemens S-7 automatic control and monitoring system. A PC system is offered for visualization; it can be fitted with on-line access for remote monitoring and support.
For applications with lower cooling requirements, the product range is supplemented by systems based on piston expanders.
The LR-Series continues to set the benchmark for helium refrigeration systems.