A magnet system generates a highly stable magnetic field at a sample location. The magnet system has a magnet cryostat housing a first superconducting magnet coil and a second magnet coil co-axial to the first magnet coil. The second magnet coil is short-circuited in a superconducting persistent mode during operation of the magnet system. An external power supply during operation supplies current to the first magnet coil via a current lead thereby generating a first magnetic field at the sample location that fluctuates according to the current noise of the power supply, wherein the second magnet coil is positioned and dimensioned in a way that it inductively couples to the first magnet coil such that it generates at the sample location a second magnetic field that compensates the fluctuations of the first magnetic field.