Abstract: A gradient coil specifically designed to enhance the performance of Magnetic Resonance (MR) imaging and spectroscopy. In particular, the construction of gradient coils for use with resonant gradient power supplies to provide the necessary performance (large electromagnetic fields that can activated and deactivated rapidly) required in MR systems. These gradient coils require considerably less power than those presently employed for comparable performance and provide considerably more performance with existing power supplies. These coils are characterized by having a higher inductance than existing gradients of comparable size. Examples are given for the use of the invention in providing linear axial gradient field via a standard Maxwell gradient coil, with comparisons with existing coils.

Abstract: A primary gradient coil and a screen coil for use with the primary coil are constructed to create a substantially null field adjacent to the screen coil and a substantially distortion free linear gradient field adjacent to the gradient coil. A method is disclosed for generating the coils by considering the screen coil to be of infinite length, deriving a Fourier transform of the axial and other components of the field in which the transform is the sum of the permissible harmonic modes on the coil surface in which a coefficient C.sub.n is derived representing the nth harmonic. A perfect screen coil is created and the number of terms C.sub.n selected using least squares optimization until there is no longer a significant change in the resulting field. Examples are given for creating unscreened, screened, linear, axial and transverse gradient field coils.

Abstract: The screen is provided by surrounding the coil producing the magnetic field with a set of electrical conductors the currents within the conductors being controlled in such a manner that the field is neutrailized in a specific region of space, the current distribution within the conductors being determined by calculating the current within a hypothetical superconductive shield which would have the effect of neutrailizing the field, the current through the conductors thereby being a substitute for the superconductive shield.

Abstract: A magnetic coil comprising a plurality of conductors is designed by calculation of the continuous current density required on the surface on which the conductors are positioned to generate a specific magnetic field on a further target surface or at specified points.

Abstract: A magnetic field of required strength is provided in a desired space by a set of electrical conductors supplied with an electrical current or currents the current distribution being determined by the induced surface current distribution in a conductive former shaped to be of the same shape as the set of conductors. This enables magnetic coils of complex design to be readily designed.