Cryogen Free Measurement System
An Automated Cryogen Free System for the Measurement of a Variety of
Physical Properties over a Range of Magnetic Fields and Temperatures
Principle Components of the Cryogen Free Measurement System
Cryogen Free Magnet – Field options of 5 Tesla to 18 Tesla
Cryogen Free Integrated Variable Temperature Insert (CFiVTI) operating from 750K to 1.6K.
Experiment Options for the Cryogen Free Measurement System:
Vibrating Sample Magnetometer (VSM).
• Vibrating Sample Magnetometer (VSM).
• AC Susceptibility
• AC calorimeter to measure the Specific Heat capacity of samples.
• Thermal Transport module.
• Resistivity and Hall Effect probe with sample rotation.
• Cryogen Free Helium-3 or Dilution Refrigerator modules.
The magnet operates dry and no liquid cryogens are required, even at start up.
The Cryogen Free platform uses our long established and patented technology to allow a magnet and variable temperature sample space to be operated from a single cryocooler in a way that allows precise temperature control while varying the magnetic field.
The system consists of a Cryogen Free superconducting magnet, variable temperature sample space, a set of special probes which carry the sample, as well asthe electronics, computer and measurement software.
The standard temperature range is 1.6K to 300K with fields up to 18 Tesla. There is a heated sample platform to extend the temperature range upwards and a Helium-3 option is available which allows temperatures to under 300mK
CRYOGEN FREE MAGNET AND CRYOGEN FREE SAMPLE SPACE
The cryomagnetic system consists of the cryogen free, high field superconducting magnet (5 to 18 Tesla), the integrated variable temperature sample space (CFVTI),
cryocooler and compressor, multi-channel temperature monitor, sample temperature controller and power supply. The cooling for the magnet and sample is provided by
the cryocooler with a base temperature of less than 4K, providing up to 1.5 Watts of cooling power on the second stage. The current to the magnet is supplied by a
Cryogenic’s specially designed power supply using current leads of HTS conductor. A Lakeshore model 340-temperature controller (or equivalent) controls the
temperature of the sample.
The cryomagnet will be delivered as a turnkey working system tested and ready to operate on delivery. No additional special equipment will be needed nor will previous cryogenic experience be necessary to operate the system.
The magnet is produced using our proven technology for high field superconducting magnets. These magnets are manufactured using copper stabilized filamentary superconductor which is then vacuum impregnated with epoxy resin to form a composite structure of excellent mechanical strength and electrical insulation. The filament size and conductor type is chosen to eliminate flux jumps.
The magnet operates in vacuum and is cooled by conduction. It is passively protected against damage caused by accidental quench whether this is caused by mains power failure or by exceeding the operating temperature of the magnet or by exceeding critical current of the superconductor.
Cryogen Free Integrated Variable Temperature Insert (CFVTI)
The cryomagnet system incorporates a Variable temperature sample space of 25mm or 30mm cooled by gas flow. A single cryocooler is used to cool both the VTI and the magnet using our patented design. Helium gas is circulated using a room temperature dry pump and cooled by the first and second stages of the cryocooler to 4K at which point it condenses into liquid helium. The liquid is collected in a small buffer tank just below the second stage. From here it is drawn off and expanded through a Joule Thompson needle valve to achieve a temperature of 1.6K. The gas then passes through a heat exchanger controlled to achieve the set temperature and from there to VTI sample space. The exchange gas in the sample chamber ensures rapid temperature change and good thermal contact to the sample.
The temperature of the sample chamber is varied by using a heater and Cernox thermometer on the heat exchanger which is controlled by a temperature controller (Lakeshore 340).
Samples are top loaded into the sample access column via an airlock and gate valve located at the top of the VTI to allow access to the centre of the temperature-controlled region.
A helium gas reservoir (50 litre NTP capacity) is supplied filled with helium gas at one atmosphere. The gas used is 99.995% purity and in the event of accidental contamination, when changing samples for instance, the gas can be replaced at low cost.
All the measurement probes are designed to top load into the variable temperature sample space.
Experienced operators can typically change samples in a few minutes.
Researchers can choose the Experiment Measurement Options that meet their immediate requirements and add-on or upgrade measurement options in the future
High Temperature Option
To perform measurements at above room temperature, two separate heated sample mounts are offered for electrical or magnetic measurement systems, which increase the standard temperature range. In normal operation, the system has a continuous temperature range of 1.6 to 300K. With these inserts the range can be extended to a temperature range of up to 750K.