Method for charging a superconductor bulk magnet by field-cooling, with at least one non-homogeneous magnetic field component of the applied charger magnetic field

A method for charging a superconductor bulk magnet by field-cooling using a magnet charger system, wherein the magnet charger system comprises a background charger magnet and a field adjustment unit,

• wherein the superconductor bulk magnet comprises a bulk magnet bore, wherein the bulk magnet bore contains a sample volume,
• wherein the background charger magnet comprises a charger bore, wherein the superconductor bulk magnet is arranged within the charger bore, wherein the background charger magnet and the field adjustment unit are arranged radially outside the bulk magnet bore, and wherein the superconductor bulk magnet has a critical temperature Tc;
• said method comprising:
• step a) charging the magnet charger system to thereafter generate a first magnetic field in the sample volume, wherein the superconductor bulk magnet has a temperature T, with T>Tc;
• step b) cooling the superconductor bulk magnet to a temperature T<Tc;
• step c) discharging the magnet charger system, which inductively charges the superconductor bulk magnet, such that the superconductor bulk magnet traps a second magnetic field in the sample volume;
• before said step a), determining a correlation between a magnetic field applied by the magnet charger system from outside the superconductor bulk magnet and a resulting magnetic field trapped by the superconductor bulk magnet at least approximately in the sample volume, in said step a), setting the field adjustment unit such that the first magnetic field generated by the magnet charger system in the sample volume comprises a homogeneous magnetic field component and at least one non-homogeneous magnetic field component,
• wherein the at least one non-homogeneous field component is chosen, using the correlation, such that the second magnetic field of said step c) has a higher homogeneity than the first magnetic field of said step a) in the sample volume,
• wherein the correlation is chosen with a linear function for each applied non-homogeneous magnetic field component comprised in the first magnetic field and to be adjusted by the field adjustment unit,
• wherein each linear function is defined by a slope and an offset, and correlates a component strength value of the magnetic field applied with a corresponding component strength value of the magnetic field trapped for the non-homogeneous magnetic field component, and
• wherein said determining of the correlation includes at least determining the offset for each linear function by calculation and/or by measurement.