CRYOGENIC LTD

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• SQUID Magnetometer
• Liquid helium cooled
• Re-condensing
• Cryogen Free

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Possible approaches to SQUID Magnetometer
Concept 1 Liquid Helium cooled system with Low
loss cryostat Concept 2 Liquid helium with
re-condenser. Concept 3 Dry systems /
Cryogen Free Systems The magnet is cooled
directly and operates in vacuum. The sample is
cooled by a secondary helium circuit using 50
litres NTP of He gas.
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Background
Cryogenic Ltd is a recognised leader for the
development and manufacture of advanced High
Field Measurement Systems for the study of the
electrical, magnetic or thermal properties of
materials. With proven experience in high field
superconducting magnets up to 21 Tesla and low
temperature equipment operating with and without
the use of liquid helium, Cryogenic can offer the
optimum solution for every type of research at
high field and low temperature.
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Approaches to cool the SQUID Magnetometer

• Concept 1 Conventional liquid helium or
  Nitrogen shielded system.
• 50 litres reservoir for liquid helium or
  Nitrogen.
• 2 to 4 litres per day of helium consumption.
• 5 litres per day liquid Nitrogen.
• Concept 2 Zero boil-off system with
  re-condenser.
• 50 litres reservoir with Pulse Tube cooler for
  Zero boil-off system.
• No liquid Nitrogen.
• 6.5 kW compressor water cooled
• Concept 3 Dry systems / Cryogen Free Systems
• No liquid helium or nitrogen
• The magnet and the sample space are cooled
  directly by a 1 Watt Pulse Tube cryocooler and
  operates in vacuum.
• 6.5 kW compressor water cooled

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The S700X System Structure

• A Superconducting Magnet to 7 Tesla
• Continuous operation from 320K down to 1.5K
• A Variable Temperature Sample Space of 9mm with
  He-4 Gas
• 10-8 EMU sensitivity for total moment
• He-3 for temperatures down to 300mK
• Oven option to 700K
• Electronics Rack
• LabVIEW operating software

• Options
• AC and DC measurements
• Oscillator and extraction mode
• MilliTesla field resolution
• Full environmental Shielding built-in.
• Flexible open LabVIEW software
• Fast 20 bit data acquisition
• Real data access during measurement
• Transverse field

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Zero boil-off Cryostat

• Cooling via ultra quiet 1 Watt Pulse Tube
  Cryocooler
• 45 litres of liquid helium reservoir.
• The Cryocooler reliquifies the helium gas from a
  cylinder at the rate of 2 litres per day.
• Cryostat required to be filled initially once
  only with 100 litres of liquid for pre-cool.
  Thereafter the liquid helium reservoir is filled
  and maintained by the Cryocooler.
• Full magnetic shield built into the cryostat to
  protect the system from external influence.
• Short- term fluctuation in heat load such as from
  ramping the magnet will not result in liquid
  helium loss as the system is supplied with a
  buffer tank full of reserve of helium gas.

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Pulse Tube Cryocooler Stability Measurements
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Cryogen Free Cryostat

• Integrated Cryogen Free VTI with a sample space
  of 9mm
• Single Pulse Tube cryocooler to provide cooling
  for both the magnet and the VTI
• Samples top-loaded into the sample space via the
  top of the VTI
• The PT cryocoolers provides up to 1.0 Watt of
  cooling power at 4K and more than 50W on the 60K
  stage.
• System Cool-down time from start to room
  temperature takes typically 15 to 20 hours.

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Cooling of the Cryogen Free Magnet System.

• Cooling for the system is provided by a Pulse
  Tube (PT) cryocooler.
• The PT cryocooler is quieter than the Gifford
  McMahon, has less vibration and has longer
  service intervals with lower servicing costs.
• The PT cryocoolers can provide up to 1.0 Watt of
  cooling power at 4K and more than 50W on the 60K
  stage.
• System Cool-down time from start to room
  temperature takes typically 15 to 20 hours.

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Benefits of the Cryogen-Free Platform

• Low Operating Costs - No liquid helium or
  Nitrogen required for start-up or operation. No
  costs associated with storage, transport or
  liquids and safety issues.
• Simple to use - as there are no cryogen transfers
  to make. Just switch on the cooler and wait for
  it to reach operating temperature within 24
  hours. Can be run to cooldown overnight.
• Independent and convenient operation Only
  mains electrical power is required to operate the
  system.
• Compact absence of liquid helium and nitrogen
  reservoirs means that this system is more compact
  and allows easy access to field centre.

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Competitive Benefits of the Cryogenic S700X
measurement system

• Ultra light design of the sample chamber
  allowing fast temperature changes and quick
  stability.
• Any temperature within the wide range of 1.6K to
  320K can be kept continuously, as long as there
  is liquid helium in the main reservoir (i.e for
  months at a time).
• Temperatures down to 300mK with a He-3 insert
• AC susceptibility can be cross calibrated with
  DC magnetic moment.
• Sample exchange via airlock in 10 to 15 minutes
  including cooling to 2K.
• Change of measurement options / probes in 10 to
  15 minutes.
• Removal of Remanent Field by magnet quench or
  heating in less than 30 minutes.

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Competitive Benefits of the Cryogenic S700X
measurement system

• Faster measurement than any other commercial
  susceptometer (makes more measurements per scan
  and reads in both directions)
• Full access to the operational functions
• Upgradeable to allow further measurement
  additions at a later stage
• Automated measurement sequences allowing
  unattended operation.
• High quality electronics from well-established
  producers, such as the Lakeshore Temperature
  controller, allowing high reliability and
  replacement or recalibration of measurement
  electronics, as well independent warranty and
  support
• Full environmental shielding (both magnetic and
  electromagnetic)

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Cryogen Free Variable Temperature Sample Space

• Simultaneous controlled cooling of the sample
  and magnet using a single cryocooler.
• Integrated VTI built into the bore of the
  magnet.
• Temperature range 1.6K to 300K. Optionally, a
  sample heater is used to extend the temperature
  range up to 700K.

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Automation

• All Cryogenic Measurement systems are supplied
  with complete control, monitoring and data
  acquisition software using the LabVIEW operating
  environment.
• This allows 
• Control of magnetic field
• Control of individual instruments (magnet power
  supply, temperature controller, lock-in
  amplifier, etc.)
• Combine functions into measurement sequences.
• Fail-safe shutdown even with power failure.
• Customisation of measurement sequences as the
  software is fully open-source.

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He3 Insert For Measurements Below 0.3K

• The He3 unit can be directly exchanged for the
  standard VTI to allow extension of the
  temperature range from 1.6 to 325K (VTI) to 0.26K
  100K.
• The Cryogen Free He3 units are constructed as
  stand-alone items with their own cryocooler or
  fitted permanently into a cryogen free system.

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He3 Insert For Measurements Below 0.3K
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High Temperature Option

• To perform measurements above room temperature,
  furnace or heated sample probe insert is offered
  to increase the temperature range to 700K.
• A series of measurements can be often be
  performed over the whole range from 1.6 to 700K.

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Quench Test
Magnet quenched at full field as the compressor
was stopped imitating a power failure. After the
compressor was restarted, the magnet was fully
operational in 27 minutes.
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Magnetisation of typical Paramagnetic Salt of at
base temperature
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6 Al impurity in a Ti alloy. Thermally conducted
with Si grease.
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Measurements for the SQUID Magnetometer

• DC Magnetisation of G - Fe2-O3 particles in
  silica
• The measurement consists of two parts 1.
  Measurement from 2K to 100K at 1 Tesla after zero
  field cooling
• (lower curve)2. Measurement from 100K to 2 K at
  1Tesla (upper curve)

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Measurements for the SQUID Magnetometer

• Relaxation Measurement
• The sample was cooled down to 2K in zero field,
  the first measurement was made after a field
  change of 1T. The intervals in time between
  measurements increase in 'pseudo logarithmic'
  steps. This example demonstrates continuous
  operation at temperatures below 4.2K.

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Measurements for the SQUID Magnetometer

• Magnetic Viscosity as a Function of Temperature
  of G - Fe2-O3 particles in silica

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Measurements for the SQUID Magnetometer

• Magnetic Moment of the of G - Fe2-O3 particles in
  silica Sample