Self-shielded gradient coils for nuclear magnetic resonance imaging

DETAILED DESCRIPTION These and other objects are achieved in a coil system for producing a magnetic field which comprises first and second coils.
The first coil is adapted to be coupled to a source of current for providing a first surface current on the surface of a first cylinder having a radius r.
sub.
i and an axial length z.
sub.
i.
The second coil is adapted to be coupled to a source of current for providing a second surface current on the surface of a second cylinder substantially coaxial with the first cylinder and having a radius r.
sub.
o greater than r.
sub.
i and an axial length z.
sub.
o.
The first and second surface currents are adapted to provide a magnetic field having a predetermined gradient in a predetermined dimension and a substantially constant value across the other two dimensions within the volume enclosed by the first coil and having a substantially zero value in the volume outside of the second coil.