Name: | Low Temperature Vibrating Sample Magnetometr Cryogenic Limited |
Location: | CEITEC Vysoké učení technické v Brně |
Instrument description: | The Cryogen-Free High Field Measurement System combines the latest cryogen-free technology with sophisticated measurement techniques; providing a versatile, powerful investigative device achieving low temperatures and high magnetic fields without the use of liquid helium or nitrogen. It is comprised of the following main components: · A cryostat incorporating a cryocooler, superconducting magnet and a variable temperature sample space. · Rack incorporating electronics for control and monitoring of the cryostat and any measurement options. · Measurement system software. · Sample probes · Measurement options. The cryogen-free magnet system allows the experimenter to achieve low temperatures 1.6K – 300K while applying magnetic fields between 5 and 9T to their samples depending on the specification of the purchased system. The cryocooler provides the cooling to both the magnet and the variable temperature insert (VTI). Cryo-cooler System Cooling materials to cryogenic temperatures has traditionally used liquid cryogens (usually helium and nitrogen). The same result may be achieved more simply by mechanical means, using a cryocooler. Cryocoolers operate using a helium compressor, which requires just mains power and a source of cooling water. The cryocooler high pressure helium circuit is completely independent to the rest of the measurement system. There are two types of cryocooler, the Gifford McMahon (GM) cryocooler and the Pulse Tube (PT) cryocooler. The GM cryocooler has the advantage of greater thermodynamic efficiency and reliable operation in any orientation. It uses the compressor to drive moving pistons with regenerators. The PT cooler has no cold moving parts so is quieter and has longer service intervals with lower servicing costs. The cooling takes place by the controlled expansion of the compressed helium gas. Depending on the model the cryocooler produces 10–50W at the first stage and from 0.1–1.5W at the second stage. The main function of the first stage is to cool the radiation shield around the low temperature parts of the system and to pre-cool the circulating helium. Cooling for the magnet and the VTI is provided by the second stage. The cryocooler cold head is fitted to the cryostat top plate and is accessible for servicing (by a certified engineer only). Depending on the cryocooler model the compressor may be located up to 20m from the cold head, connected by dedicated high pressure hoses. Cryostat The cryostat is a vacuum insulated chamber whose primary function is to support and thermally shield the superconducting magnet and VTI. Some systems are fitted with an optical window to allow light access into the VTI along the axis of the magnet. Superconducting Magnets Various magnets can be used in a measurement system. Typically the magnet is a vertically oriented solenoid wound from copper stabilised filamentary niobium titanium (NbTi) superconducting wire. Occasionally other magnet designs such as a horizontal field split pair may be used. The coil is cooled by the cryocooler to an operating temperature of 3 – 4 K |
Research group: | CF: CEITEC Nano |
If you would like to use this equipment contact the administrator: |
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