Nanostructure research typically
requires a highly stable sample platform. In addition to
traditional liquid helium-based (wet) systems,
Cryomagnetics offers the convenience of 4.2K pulse-tube
cooled superconducting magnet systems with variable
temperature sample operation.
Cryomagnetics' nanostructure research systems incorporate significant vibration
isolation features to insure this stability. A single,
low vibration 4.2K pulse-tube cryocooler is used to cool
both the superconducting magnet and the sample. The
cryocooler is installed using edge-welded vibration
isolation bellows and ultra-flexible thermal straps
inside the system. A vibration-isolation base stand is
used to reduce transmission of floor vibrations into the
system. The stand is compatible with extremely low
vibration isolation mounting legs used in high
resolution NMR applications requiring ultra-low
vibration. Further vibration reduction options can
include a remotely-mounted cold head motor.
The system includes a top-loading
VTI integrated into the cryostat/cryocooler assembly.
This provides the user with variable temperature access
to the high field region of the magnet. The insert is
very versatile, allowing for future upgrades of the
system to extend the low temperature range of the sample
space.
The refrigeration system is closed-loop and works as
follows: A circulation of helium gas is brought into the
system and cooled by the cryorefrigerator until it
condenses to liquid He4. This liquid is then distributed
to cool the magnet and VTI. Cooling of the VTI takes
place through a JT expansion valve, thereby allowing
samples to be cooled to as low as 1.5 Kelvin. After the
helium is used to cool the sample, it exits the system
and is then re-introduced (via a pump/compressor
arrangement) back into the system where the process is
repeated. Under normal circumstances, it is not
necessary to refill helium after the initial charge.
The sample space is nominally 38mm in inside diameter.
By increasing the sample space to 38mm, Cryomagnetics is
able to offer optional inserts and upgrades that provide
even lower base temperatures while still maintaining a
large 25mm diameter sample space.
With a 7T split-pair superconducting magnet installed,
the cryostat and VTI will be equipped with a blanked-off
bottom port and side radial ports (in line with the
magnetic axis). The bottom port allows future upgrade
with bottom windows, providing optical access to user
samples should this ever be desired. Solenoid
configurations may also have a bottom-looking window
installed if desired.
The outer vacuum casing of the system and the
intermediate thermal shield are modular and sealed using
o-rings. This makes the system very versatile.
Modifications can be easily made, and should system
service ever be required, it can be done without cutting
any metal on the system.
The VTI will be equipped with a
sample probe. The sample mount is gold-plated OFHC
copper and includes a heater and calibrated (1.5K-325K)
temperature sensor.
The system may be upgraded to
include a He3 insert or a dilution refrigerator insert
by Cryomagnetics’ affiliate company Cryoconcept. The He3
insert is a “one-shot” device that gives the user the
ability to cool samples to <300mK. A dilution
refrigerator insert option is planned that will give the
capability of cooling samples to <40mK. Additional
details are available on request.
Work is being performed to offer a continuous type He3
insert option in the near future.
All Cryomagnetics' nanostructure
research systems include a gas handling system (GHS). It
will be equipped with a vacuum pump, a compressor, a helium gas expansion
chamber, and all necessary valves, gauges, and plumbing
necessary for operation of the system. The GHS will be
mounted on a rolling cart for ease of installation.
The standard system includes manual valves for control
of the system. An automated GHS is available as an
option. The automatic system uses a touch-screen based
PLC controller to automate critical functions of the
system, thereby minimizing the risk of operating errors
by the user.
To simplify superconducting magnet
operation, Cryomagnetics' nanostructure research systems
will include Navigator™ software. Navigator is a
LabVIEW-based software package that allows complete
automation of the superconducting magnet system control
electronics.
Example Nanostructure
Research 7T Split-Pair Superconducting Magnet System Quotation
Use this example to help define your specific needs... 
Superconducting Magnet
Split-pair configuration, horizontal field.
7 Tesla maximum rated central field.
Homogeneity: + 0.01% over a 10 mm diameter spherical
volume.
Persistent switch installed.
< 2 mT remnant field after cycling to 7T.
Fully protected against damage due to accidental quench.
Integrated HTS (BSCCO-2212) magnet current leads.
The system is also available with 9T and 12T solenoid
magnet options.
Cryostat / Cryocooler
The cryostat consists of a modular aluminum vacuum
housing compatible with the superconducting magnet. A
Cryomech Model PT-415 low vibration pulse tube
refrigerator with a water-cooled compressor is used for
cooling of magnet and user samples.
Variable Temperature Insert
(VTI)
The proposed system includes a top-loading VTI
integrated into the cryostat/cryocooler assembly. This
provides the user with variable temperature access to
the high field region of the magnet. The insert is very
versatile, allowing for future upgrades of the system to
extend the low temperature range of the sample space.
The VTI will be equipped with a sample probe. The sample
mount is gold-plated OFHC copper and includes a heater
and calibrated (1.5K-400K) Cernox temperature sensor.
Gas Handling System (GHS)
The proposed system will be equipped with a GHS that
includes a vacuum pump, a compressor, a helium gas
expansion chamber, and all necessary valves, gauges, and
plumbing necessary for operation of the system. The GHS
will be mounted on a rolling cart for ease of
installation.
The standard system includes manual valves for control
of the system. An automated GHS is available as an
option. The automatic system uses a touch-screen based
PLC controller to automate critical functions of the
system, thereby minimizing the risk of operating errors
by the user.
Cryomagnetics Navigator™
Software Control System
Navigator™ is a LabVIEW-based software package that
allows complete automation of the superconducting magnet
system control electronics. The release provided with
this system contains basic control and feedback of the
quoted electronics (routine sample measurements).
Cryocon Model 44 Temperature Controller
A Cryocon model 44 temperature controller will be
provided for sample temperature control in the VTI. This
instrument is also compatible with the optional He3
insert, so if a future upgrade is desired, a change in
electronics will not be necessary.
Model
TM-600 Temperature Monitor
A Cryomagnetics model TM-600 temperature monitor will be
provided for monitoring of the refrigeration system
(magnet and shield).
Model
4G-100 Integrated Superconducting Magnet Power System
A Cryomagnetics Model 4G-100 superconducting magnet
power supply will be provided for energizing the magnet.
This unit will be configured as a single output model
with output current up to ± 100 amperes at 800 watts (±
10 volts up to 80 amperes, ± 8 volts at 100 amperes).
Electronics Cabinet
All quoted electronic instruments will be housed in a
pre-wired console.
