Tests of HQ02a and HQ02b show performance that even in the worst cases was in excess of the needs of a high-luminosity LHC (lower dashed line) and in most cases far exceeded the need. The data points are quenches (transitions from superconductivity to normal conductivity in part of the magnet, requiring its energy to be removed). Quenches are thought to result from local movement of part of the superconductor. As shown in these “training curves,” such magnets achieve their full field over the course of several quenches — a sort of break-in process that beds the superconducting coils down into a highly stable position. A trained magnet can be relied upon to deliver a certain magnetic field in an operating accelerator.