What occurs during a quench of an MRI magnet?

During a quench of an MRI magnet, liquid helium is heated and boils off. This process occurs when the temperature of the superconducting coil increases beyond its critical temperature, causing the superconducting state to break down. As a result, the liquid helium used for cooling transforms into gas, leading to an increase in pressure within the MRI system. This release of helium gas indicates that the superconducting magnet is no longer operating efficiently, which can lead to a loss of magnetic field strength and the potential for damage to the MRI system if not managed properly. This boiling off of the helium is a critical safety consideration in MRI technology.