Nanostructure research typically requires a highly stable sample platform. In addition to traditional liquid helium-based (wet) systems, Cryomagnetics offers systems based on the C-Mag magnet platform which allows for 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. For probe microscopy methods an optional pneumatically dampened anti-vibration sample rod platform is available. The sample rod mounts to this platform via standard KF fitting and is linked to the magnet cryostat via a supple edge welded bellows assembly to minimize transfer of mechanical vibration.
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 49mm in inside diameter. By increasing the sample space to 49mm, Cryomagnetics is able to offer optional inserts and upgrades that provide even lower base temperatures while still maintaining a large 25mm diameter sample space.
Available in vertical or horizontal (split pair) single axis or 2 or 3-axis vector configurations, the cryostat and VTI may be configured in traditional or optical designs which feature horizontal and bottom mounted windows to match research objectives. Optical designs feature interchangeable quartz windows which may be exchanged as needed based on wavelength requirements.
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 which allows for extended to continuous operation at <350mK or lower depending on configuration and He3 volume.
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.
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…
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 1.5Watt 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.
Cryomagnetics Navigator™ Software Control System
Navigator™ is a 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).
A Cryocon Model 24C 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.
A Cryomagnetics model TM-612 temperature monitor will be provided for monitoring of the refrigeration system (magnet and shield).
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).
All quoted electronic instruments will be housed in a pre-wired console.