Gradient coil system of an installation for nuclear spin tomography

Claim 1

A gradient coil system, for nuclear magnetic resonance tomography apparatus, enclosing a hollow cylindrical carrier (16) whose cylindrical axis extends in the z-direction of a rectangular x-y-z coordinate system whose coordinate source lies in the centre of a focussing zone, in which direction a magnetic field B z of a fundamental field magnet comprising a plurality of field coils is also orientated, and where, in order to generate a field gradient which is substandially constant in the focussing zone, the gradient coil system includes at least two individual, ring-shaped coils, arranged at least approximately symmetrical to the x-y plane (18) passing through the centre of the focussing zone, and also in each case at least one set of pairs of individual saddle-shaped coils arranged at least approximately symmetrical in relation to this plane of summetry 8B z (18) to produce field gradients which are substantially constant in the focussing zone in the x-5B z direction and corresponding field gradient in the y-direction, characterised in that: a) the pre-manufactured saddle-shaped G x and Gy gradient coils (4, 6 and 7; 5, 8 and 9, 42), which are each arranged on one side of the x-y plane of symmetry (18), are rigidly connected to one another to form a self-supporting subsidiary basket (24; 25); b) by means of a plurality of carrier elements (20 to 22, 34, 37), which extend in the z-direction and consist of non-magnetic, insulating material, the subsidiary baskets (24, 25), formed on both sides of the x-y plane of symmetry (18) provide a common, self-supporting coil basket (2) to which the pre-manufactured, ring-shaped G z gradient coils (11 to 14) are attached; and c) the coil basket (2) is applied to the hollow, cylindrical carrier component (16) via insulating, flexible support elements (71).