The magnetic resonance imaging (MRI) scanner – an electric magnetic field that is around 20,000 times stronger than the one of the Earth and would not be functional without cooling.

Most people are familiar with magnetic resonance imaging (MRI) scanners from their use in medicine. With the help of precise cross-sectional images of the human or animal body, a computer can generate an image that can be used for diagnosis by specialists.

The functioning of a magnetic resonance imaging scanner is based on what is known as magnetic resonance imaging. The strong magnetic field is generated by superconductors, which become extremely conductive at very low temperatures. These electromagnets are therefore cooled with liquid helium.

The atomic nucleus contains protons, which have a special property called spin. This property is also referred to as a kind of intrinsic rotation. This causes the protons to act like tiny magnets. This property is important for the functioning of an MRI scanner.

The spins of the protons are aligned parallel to each other in a strong magnetic field during an examination. This alignment is the lowest energy state. Additional radio waves irradiated into the sample influence the alignment of the spins, which are then in a higher energy state. After a short time (half-life), however, they rotate back to their ground state, the parallel initial direction. In doing so, the protons release the energy they previously absorbed from the radio waves via electromagnetic radiation. A computer can be used to create an image based on the position of the protons and the time it takes for the transition to occur.