American Magnetics MAxes Multi-Axis Magnet systems for Vector Fields User Manual

Multi-Axis Magnet systems for Vector Fields (MAxes
significant progress in technologies that allow sample manipulation at atomic level, however at sub Kelvin temperatures, there is limited thermal budget and hence it’s preferable to rotate the magnetic field than rotating the sample. Additional constraints come into play when systems are cooled using closed cycle coolers as thermal budget is further restricted. Some of these requirements have pushed advancements in areas of Multi-axis magnets, as using these it is possible to align samples in magnetic field to an accuracy of better than 0.01 degrees.
A typical MAxesTM magnet is comprised of two or three independently controlled coil sets. A solenoid coil produces the highest field along one axis. One or two sets of split coils produce fields along the other 2 axes. By correctly energizing the coils with programmed coil constant a combined vector field can be produced in a given direction of a known magnitude. This allows users to electronically manipulate the field relative to the sample without the use of complex sample rotation equipment or physically rotating the magnet position. Coil configurations could be with the split coils surrounding the solenoid or the split coils nested inside the bore of a large solenoid. Typical specifications include high field up to 9 Tesla (T) for the principal axis, having 2.0/3.0 inch vertical clear bore and 1T or 2T rotating vector using any combination of x, y and z-axis magnets. Users needing higher vector field typically opt for 2-axis systems.
The following table gives a snap shot sample of the capabilities of our MAxesTM systems.
Bore size MX-2 (YZ) 2D Vector field MX-3 (XYZ) 3D Vector field
2.0"
2.5"
3.0"
4.5T/9T 4.5T 1T/1T/12T 1T 2T/2T/9T 2T
5T/7T 5T 1.5T/1.5T/9T 1.5T
5T/6T 5T 1T/1T/9T 1T
TM
)
American Magnetics, Inc. Multi-Axis (MAxesTM) systems allow the user to easily program an infinite number of high magnetic field vectors. Our combination of user friendly electronics, reliable cryogenic vessels, and robust multi­axis superconducting magnets combine to make our MAxesTM systems an excellent choice for any application where the outcome is dependent on precise magnetic field vector orientation. Transport studies on anisotropic materials at high magnetic fields & low temperatures have revealed many exciting properties. Even though anisotropic magneto resistance is a century old phenomena, advancements in nanotechnology has created increased importance to attain precision angular control, while positioning samples in magnetic field. There has been
Cartesian, cylindrical, or spherical coordinates (2-Axis in Cartesian or polar). Once the desired vectors are specified in tabular format or as read from a file, a “NEXT VECTOR” control from the program initiates appropriate control commands to the AMI power supply programmers which are connected via an RS­232/GPIB or an Ethernet port.
MAxesTM MX-2 (2-axis) Vector Magnet System
Forces in such magnets can be extremely high due to the interaction between each coil when they are energized simultaneously. Care must be taken to stay within the factory defined operating envelop or one could end up damaging the magnet and cryostat. This risk is minimized by operating multiple coils of the MAxesTM system using AMI’s Free LabVIEW virtual interface which allows the users to specify and control the magnetic field vector from a single computer screen. High resolution power supplies are computer controlled using an AMI model 430 power supply programmer. The programmer is also web enabled using an Ethernet option. Infinite combinations of magnetic field vectors are hence possible. Calculated field components, based on actual current measurements and predetermined coil constants for a given magnet, are continuously displayed on the screen. The interface allows the users to enter in the desired field vector of a 3-axis magnet in
Over the last few years American Magnetics has delivered wide ranging 2-axis systems with vector fields ranging from 1T to 5T. These have been offered for different bore sizes for use with He3 inserts and dilution fridges. American Magnetics has excellent working relationships with various OEM’s and we work diligently to offer customized solutions. With the advent of high power pulse tube cryocooler technology, Cryogen free magnet systems are becoming virtual research laboratories in various branches of condensed matter physics. AMI offers cryogen free MAxesTM systems in both dry and recondensing geometry. The picture on the left shows a conduction cooled MAxesTM magnet integrated with dilution refrigerator manufactured by Leiden Cryogenics. It is a 2-axis 3T/9T conduction cooled magnet and offers 3T vector field with 9T in vertical plane. Users desiring to use existing inserts that operate in liquid He may opt for Recondensing style systems. The recondensing configuration produces Near Zero He Boil-off systems (NZHB) and allows users to benefit from the latest technology without investing in new and expensive sample insert.
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