A magnetic stimulation device for treatment of a patient using a time-varying magnetic field, wherein the magnetic stimulation device comprises: an energy source, a switching device, a magnetic field generating device, an energy storage device and a casing wherein the magnetic field generating device is attached to the casing, wherein the casing has an inlet configured to direct fluid cooling media to the casing so that the magnetic field generating device is configured to be cooled by the fluid cooling media; the magnetic field generating device is connected to the energy storage device and to the switching device; the energy storage device is configured to be charged by the energy source; the switching device is configured to be switched to enable to discharge energy from the energy storage device to the magnetic field generating device so that the magnetic field generating device generates an impulse of the time-varying magnetic field, wherein the impulse has an impulse duration in a range of more than 10 μs and less than 1 ms, a peak-to-peak magnetic flux density in a range of 0.15 Tesla to 7 Tesla, and a repetition rate in a range of 1 to 700 Hz; the magnetic field generating device is flat and the magnetic field generating device comprises a plurality of insulated wires, wherein each wire is insulated individually to reduce eddy current energy losses so that a voltage drop in the energy storage device between successive amplitudes output from the energy storage device is not higher than 21 %; the time-varying magnetic field is configured to be applied to the patient, wherein the treatment by the time-varying magnetic field lasts at least 5 seconds or longer. an energy source, a switching device, a magnetic field generating device, an energy storage device and a casing wherein the magnetic field generating device is attached to the casing, wherein the casing has an inlet configured to direct fluid cooling media to the casing so that the magnetic field generating device is configured to be cooled by the fluid cooling media; the magnetic field generating device is connected to the energy storage device and to the switching device; the energy storage device is configured to be charged by the energy source; the switching device is configured to be switched to enable to discharge energy from the energy storage device to the magnetic field generating device so that the magnetic field generating device generates an impulse of the time-varying magnetic field, wherein the impulse has an impulse duration in a range of more than 10 μs and less than 1 ms, a peak-to-peak magnetic flux density in a range of 0.15 Tesla to 7 Tesla, and a repetition rate in a range of 1 to 700 Hz; the magnetic field generating device is flat and the magnetic field generating device comprises a plurality of insulated wires, wherein each wire is insulated individually to reduce eddy current energy losses so that a voltage drop in the energy storage device between successive amplitudes output from the energy storage device is not higher than 21 %; the time-varying magnetic field is configured to be applied to the patient, wherein the treatment by the time-varying magnetic field lasts at least 5 seconds or longer.