Patent ID: 6972652

Claim:
A method for charging a magnet system which is superconductingly short-circuited during operation via a superconducting main switch, to generate, in an investigational volume, a homogeneous temporally stable magnetic field B which extends in a z-direction, wherein the magnet system comprises at least one first and one second partial region, wherein said first partial region can be separately superconductingly short-circuited via an additional superconducting switch and the second partial region cannot be short circuited by that additional switch, said first and said second partial regions generating magnetic fields in the investigational volume during operation whose expansion coefficients B 2 (1) and B 2 (2) of second order in z have opposite signs, the method-comprising the steps of: a) charging the magnet system with open main switch and open additional switch using a supply unit to a first current strength value I 1 ; b) measuring a magnetic field dependence B* in the investigational volume along the z-axis of the magnet system; c) calculating an expansion coefficient B* 2 =d 2 B*/dz 2 of said magnetic field dependence B* measured in step b); d) determining additional currents ΔI (1) and ΔI (2) in said first and said second partial regions, said additional currents ΔI (1) and ΔI (2) being selected to produce an additional magnetic field dependence in the investigational volume having an expansion coefficient of −B* 2 ; e) calculating a second current strength value I 2 throughout the magnet system at which said additional switch shall be closed, and a third current strength value I 3 of said second partial region at which said main switch shall be closed such that, taking into consideration mutual inductance between said first and said second partial region, after reaching said third current strength in said second partial region, a current distribution in said first and said second partial regions as given by I (1) =I 2 +ΔI (1) and I (2) =I 3 =I 2 +ΔI (2) generates a desired magnetic field B; and f) continuing charging the magnet arrangement while closing said additional switch when I 2 has been reached and while closing said main switch when I 3 has been reached, wherein I 2 is obtained prior to I 3 .