Opening Angle
Bore: +/- 5°
Split: +/- 3°

General Info:

• Magnet Design:
  Our superconducting magnets (SCMag) are designed specifically for neutron scattering. The magnet geometry and cryostat design allow maximum neutron beam access. Samples are housed in a variable temperature insert that is thermally isolated from the magnet, allowing the researcher to examine temperature and magnetic field dependent effects. Presently, all of our systems are cooled with liquid helium.  The magnet normally operates at 4.2 Kelvin, but if a lambda option is available, additional cooling to ~2.2 K is possible.
  
• Superconducting Magnet Materials:
  Conventional low temperature alloy ( e.g. NbTi) in the form of filaments embedded in an ohmic conductor and wound into a solenoid
  
• Maximum Fields:
  The 11.5 Tesla dilution refrigerator is currently our highest field system. However, we just added an 11 Tesla magnet that is simpler to use and has a broader temperature range. The 9T is our highest field and only horizontal field system.
  
• Quenching:
  The SCMag may undergo an abrupt transition from the superconducting to the resistive state. Sometimes the cause is clear ( e.g. exceeding the maximum rated field, ramping the current too rapidly) and sometimes not. The most obvious sign of a quench is a surge of exhaust from the helium bath. This may be loud and alarming, but all of our SCMag systems are designed to handle a quench safely.
  
• Persistent Switching:
  Once the SCMag is energized and operating at steady state, the external current source is no longer needed and may be effectively removed from the circuit by means of a persistent switch.
  
  

  Persistent Switch (PS) Schematic The PS is comprised of a resistive heater in thermal contact with a segment of superconducting wire that is connected in parallel with the magnet solenoid (M). When the heater is energized with a small current (~ 50mA), the wire segment becomes resistive and a voltage may be applied across M, allowing it to be energized/de-energized. When the persistent switch heater is turned off, the wire segment goes into the superconducting state and shorts the magnet. The external current source may then be run down while the superconducting current in the magnet persists.

  
  
• Symmetric and Asymmetric Modes:
  Most experiments will use a symmetric field configuration, but a polarized neutron beam experiment will require an asymmetric field to prevent beam depolarization
  
  

  A split-coil SCMag with independent solenoids (M1 and M2) and persistent switches (PS1 and PS2) . Here, the center tap (CT) is used for independent control of M1 and M2 (asymmetric mode). For symmetric operation, one may connect the solenoids in series and persistent switches in series (no connection is made at CT).  Note that not all magnets are capable of operating in asymetric mode.

  
  
• Sample Mounting:
  Sample mounting information for superconducting magnets and all other sample environment equipment can be found here .