Patent ID: 9658303
Date: 2017-05-23
CPC Classifications: G01R,Y10T

Claim:
1. An actively shielded gradient coil system for use in a magnetic resonance device, the gradient coil system generating a main magnetic field oriented in a direction of a z-axis, wherein, when a current flows, the gradient coil system generates a gradient field in a measuring volume through which the z-axis extends, the gradient coil system comprising: a main coil, said main coil occupying a first radial partial area which extends in a radial direction with respect to the z-axis from r_min_1( a shielding coil, said shielding coil occupying a second radial partial area which extends in said radial direction with respect to the z-axis from r_min_2( at least one correction coil, wherein active conductor elements of said correction coil lie outside of said first and said second radial partial areas in each plane perpendicular to the z-axis, said at least one correction coil being electrically connected in series with said main coil and with said shielding coil, active conductor elements of all correction coils together occupying maximally one quarter of an azimuthal angle range with respect to the z-axis, wherein, in comparison to a gradient coil system without correction coil, said at least one correction coil reduces a time duration of eddy currents, which are induced in a vicinity of the gradient coil system due to rapid changes in the current flowing in the gradient coil system.