Magnet Options

A Persistent Mode Switch is an option for increasing the stability of superconducting magnets over long periods of time. With persistent mode, the magnet’s external power supply can be turned off during operation and the magnetic field is preserved by a persistent current.

The stability of the magnetic field with persistent mode is better compared to using the external power supply. The Persistent Mode Switch is installed on the magnet and becomes an integral part of it. The Persistent Mode Switch is available for all magnets.

The Persistent Mode Switch comprises a superconducting wire connected across the input terminals of the magnet, and an integral heater. The heater drives the wire into a resistive state, which allows the magnet to be energized before engaging the persistent mode by turning off the heater. Once the wire cools down, it becomes superconductive, and the current continues to circulate through the magnet and the Persistent Mode Switch.

Magnets with this option are equipped with the low-drift option for the persistent mode switch, which means that the magnet is manufactured with extra testing for the joint between superconducting wires of the coil and the persistent mode switch. This guarantees better magnetic field stability compared to the regular persistent mode switch.

Vector magnets with this option can be used in any combination of simultaneous fields on each axis. However, the ramp rate for each coil must be adjusted so that each coil reaches the target field simultaneously. The magnetic field cannot be freely rotated. Instead, you must go through zero to change the direction of the magnetic field vector. The magnetic field vector is rotatable up to the limit specified for each magnet.