Minimum stored energy MRI superconducting magnets: From low to high field

The aim of this article is to describe superconducting magnet coil arrangements from low to high field, particularly from 1T to 7T, within the context of the minimum stored energy designs. The findings illustrate that at low field, the maximum peak magnetic fields are located away from the most inner coils of the magnet configuration, whereas in high field designs, the maximum peak magnetic fields are created on coils lying on the inner diameter of the magnet bore. This becomes a critical aspect of any high field design, since there appears to be much less freedom of design at higher fields, due to the inherent limitations posed by peak magnetic fields on superconductors. Our findings also indicate that at low fields, 3T and less, reverse current coils can be used to shorten superconducting magnets, whereas at high field, above 3T, this is not necessarily the case, due to the large peak fields produced between adjacent, alternating current coils.