Low Temperature Vibrating Sample Magnetometr Cryogenic Limited (CRYOGENIC)


Guarantor:
Klára Jelénková

Instrument status:
Operational Operational, 11.8.2020 07:38

Equipment placement:
CEITEC Nano - C1.56

Upcoming trainings:
30.9. 09:00 - 12:00: CRYOGENIC DCR - Cryogenic DCR training. In case you are interested in a training and the limit is full, please contact the guarantor.


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 up to 9T to their samples. The cryocooler provides the cooling to both the magnet and the variable temperature insert (VTI).


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Specification

Instrument is comprised of the following 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 (two types - VSM, Resistivity).

Cryocooler system and cryostat

Cooling materials to cryogenic temperatures has traditionally used liquid cryogens (usually helium and nitrogen). The same results 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. However, it provides the cooling to both the magnet and the variable temperature insert (VTI). The cryostat is a vacuum insulated chamber whose primary function is to support and thermally shield the superconducting magnet and VTI.

Superconducting magnet

The magnet in our system is a vertically oriented solenoid wound from copper stabilised filamentary niobium titanium (NbTi) superconducting wire. The coil is cooled by the cryocooler to an operating temperature of 3–4 K.


Main parameters


Magnet

Magnet type NbTi solenoid with persistent mode switch
Central field homogeneity 0.1% over 10mm diameter x 10mm long cylinder
Decay rate in persistent mode (ppm/hr) 10
Field direction Vertical
Magnet inductance (Henries) 5.3 H
Maximum Operating Field (Tesla) 9 T
Magnet constant 0.08309T/A
Nominal operating current (amps) 108.3 A
Radial stray field 5 gauss contour (m) 1.3 (from centre of magnet)
Vertical stray field 5 gauss contour (m) 1.6 (from centre of magnet)
Initial magnet energisation rate 0.3 T/min
Maximum subsequent energisation rate 1.0 T/min
Magnet power supply Cryogenic SMS120C (120A, +/-5V)
Low field option +/=300mA (24 mT)

Cryocooler (Water cooled Compressor)

Type Sumitomo 1 W Pulse Tube Cryocooler
Compressor mains requirements 410 V, 3 phase, 16A or 32A
Compressor cooling water minimum flow rate (l/min) 7
Static compressor gas pressure (bar) 17.0
Working compressor gas pressure (bar) 21
Typical cooldown time (hrs) 11

VTI

Temperature range (K) 1.6–400
Temperature stability (K) +/- 0.05
Internal diameter (mm) 25
Normal operating pressure (mbar) 5–15
Dump vessel pressure with system at room temperature Atmosphere plus 0.25 bar (approx)
Dump vessel pressure with VTI at base temperature Atmosphere minus 0.5 bar (approx)

Sample chamber

Variable temperature insert without VSM coils inserted Circulating helium gas 25 mm inner diameter
With VSM coils inserted Static exchange gas 14 mm inner diameter


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