Layout of the Gersemi vertical cryostat with its valve box and helium liquefier (Image: Uppsala University, FREIA Laboratory, Philippe Bujard)

Gersemi is a vertical cryostat system for testing superconducting magnets and cavities located at the FREIA Laboratory, Department of Physics and Astronomy, Uppsala University, Sweden.

The facility allows users to characterize their devices in either saturated or sub-atmospheric liquid helium baths, with a diameter of 1.1m and a height of 2.8m. The range of operation is 1.8 to 4.5~K.

A project based at Gersemi is expected to last typically for three weeks. It is estimated that the installation of equipment will take one week, followed by a week of cooling and measurement, and finally a week to warm up the facility so equipment can be removed.


  • 2x 2000 A four quadrant power converters
  • Up to 1 kW RF power in a self-excited loop (for cavities)
  • Standard measurement equipment, ie vector network analyser, frequency generator, oscilloscope.
  • Data acquisition and monitoring system
  • Mechanical and electric workshop services (for installation and maintenance)

Support offered

Users may choose whether to participate in the preparation and installation of the equipment or whether facility staff should carry this out.

Facility staff will operate the facility and will be available to advise and assist with testing scenarios. Users can take the lead during the measurement campaign.

Logistics support can be arranged through local providers by facility staff.


Interested parties are encouraged to contact the Facility Coordinator before beginning the formal application process with brief details of the test campaign proposal. 

Gersemi Facility Coordinator: Roger Ruber