Abstract: A cryostat arrangement for keeping liquid helium comprising an outer shell (2), a helium container (6) installed therein and a neck pipe (4) extending from the helium container to the outer shell whose upper warm end is connected to the outer shell and whose lower cold end is connected to the helium container, wherein the outer shell, the helium container and the neck pipe define an evacuated space (13) containing a radiation shield (15) surrounding the helium container and being connected at a coupling to the neck pipe in a heat-conducting fashion, wherein a refrigerator is installed in the neck pipe having a cold finger (5a) which consists of at least one pipe and projects into the neck pipe, is characterized in that at least one pipe of the cold finger is surrounded by at least one separating body (3a) which divides the neck pipe into two partial volumes (8a and 9a) which are connected to one another through a lower opening (10a) and an upper opening (7a).

Abstract: An actively shielded, superconducting magnet arrangement for the generation of a magnetic field in the direction of a z axis in a working volume arranged about z=0, having a radially inner and a radially outer coaxial coil system, wherein the two coil systems carry the same current and have dipole moments of the same magnitude, but of opposite directions, wherein parts of the radially outer coil system (C2′) are electrically connected in series with the radially inner coil system (C1) and wherein a first superconducting switch (S1) is provided via which during operation a superconducting short circuit of a first current path of the magnet arrangement can be effected, is characterized in that a section (A′) of the radially outer coil system (C2′), which can be superconductingly short-circuited during operation via a further superconducting switch (S2) is arranged symmetrically to the plane z=0 and that the further superconducting current path formed by the superconductingly shor

Abstract: An iterative method of homogenizing the magnetic field in the working volume (8) of the main field magnet (1) of a magnetic resonance apparatus uses ferromagnetic homogenizing elements (6) which are mounted at predetermined positions (9) on one or more support bodies (5), wherein in a first measuring step, the profile of the magnetic field is determined through measurements and in a first calculation step, occupation by homogenizing elements (6) at the predetermined positions (9;29) is calculated such that the calculated overall field, i.e.

Abstract: A magnet coil arrangement comprising an actively shielded superconducting primary circuit (21) comprising first and second magnet windings (1,2,3 and 4,5), and being wound e.g. in winding chambers (7,8,9 and 10,11) in a supporting body (6a,6b) for generating a strong magnetic field in a working volume with a small magnetic stray field and a short circuited secondary circuit (22) which is inductively coupled with the primary circuit (21) and contains third and fourth magnet windings (13,14,15 and 16,17) is characterized in that the magnet windings (13,14,15 and 16,17) of the secondary circuit (22) form an approximately actively shielded magnet coil. This permits a simple and robust coil protection for actively shielded superconducting magnets during a quench wherein the superconducting magnet windings are reliably relieved and the magnetic stray field of the entire arrangement remains small.

Abstract: A cryostat arrangement for keeping liquid helium comprising an outer shell (2), a helium container (6) installed therein and a neck pipe (4) extending from the helium container to the outer shell whose upper warm end is connected to the outer shell and whose lower cold end is connected to the helium container, wherein the outer shell, the helium container and the neck pipe define an evacuated space (13) containing a radiation shield (15) surrounding the helium container and being connected at a coupling to the neck pipe in a heat-conducting fashion, wherein a refrigerator is installed in the neck pipe having a cold finger (5a) which consists of at least one pipe and projects into the neck pipe, is characterized in that at least one pipe of the cold finger is surrounded by at least one separating body (3a) which divides the neck pipe into two partial volumes (8a and 9a) which are connected to one another through a lower opening (10a) and an upper opening (7a).

Abstract: The windings of an NMR magnet coil are formed of at least two adjacent non-crossing conductor paths which are electrically insulated from one another. Each conductor path of a partial coil can be transformed geometrically into one respective conductor path in each partial coil through the symmetrical operations. The various conductor paths in each partial coil are coded in such a manner that the conductor paths adjacent to one another in a winding and attributed with identical successive cardinal numbers as code numbers in their geometric order. The conductor paths in the various partial coils which can be transformed into one another through symmetrical operations have the same code numbers. Each conductor path in a partial coil is electrically connected in series with one conductor path each in at least one other partial coil. These series connections of conductor paths are electrically connected to one another in parallel.

Abstract: A gradient coil (1) to generate switched magnetic field gradients in an nuclear spin resonance (NMR) device consisting of one or several current paths (a, b) following windings and being arranged on the surface of a geometric body is characterized in that at least two electrical current paths (a, b) are provided for, running geometrically essentially parallel to each other and being electrically connected in parallel, which current paths cross n times per winding, wherein n is an integer with n.ltoreq.8, preferably n=1 or n=2. In this way, eddy current generation by current re-distributions on the gradient coil conductor strips and thereby a time-dependent distortion of the generated magnetic field gradient inside the volume of interest of the NMR apparatus is considerably reduced.

Abstract: Magnet arrangement for a one-sided NMR tomography system having a permanent magnetic ring (4) of an outer radius R.sub.a and an inner radius R.sub.i and being magnetized axially in the direction of the z-axis and extending in the axial direction up to a plane E (z=z.sub.E) for generating a homogeneous magnetic field B in a measuring volume (2) is characterized in that, in a radial region R<R.sub.i, at least one further permanent magnetic field-generating element, which is rotationally symmetric, is arranged with respect to the plane E on the same side as the permanent magnetic ring (4) at an axial distance from plane E, whereby a depression V is formed on the surface of the magnet arrangement (1) facing plane E and that the permanent magnetic field-generating elements generate at least 90%, preferably 99% of the homogeneous magnetic field B in the measuring volume (2).

Abstract: A gradient coil system for the production of a magnetic transverse gradient field G.sub.x =dB.sub.z /dx in an NMR tomograph has axial and transverse access to the measuring volume. The gradient coil system consists of four partial coils (S.sub.1x, S.sub.2x, S.sub.3x, S.sub.4x) each with two current connections (A.sub.1, A.sub.2), which are arranged mirror symmetrically with respect to the xy-plane (z=0) and mirror symmetrically with respect to the zy-plane (x=0). Each partial coil comprises winding sections on an inner and on an outer cylinder Z.sub.1x, Z.sub.ax) about the z-axis as well as on a radial connecting surface V.sub.+x, V.sub.-x and the radial connecting surfaces V.sub.+x, V.sub.-x of those partial coils (S.sub.1x, S.sub.4x ; S.sub.2x, S.sub.3x,) which face each other opposite the xy-plane are essentially identical. An axial gap for free transverse access to the measuring volume remains between the partial coils.

Abstract: An NMR tomography magnet system (1) comprises a cryostat having a horizontal room temperature bore (2) with a diameter d between 20 cm and 40 cm having a vessel (3) filled with liquid helium. In intimate thermal contact with the liquid helium is a superconducting solenoid coil (4) with a horizontal axis (100; z=0) for the production of a static homogeneous magnetic field B in a homogeneity volume (5) within the room temperature bore (2). The center of the homogeneity volume is located at a separation l.sub.m from an axial end (z=0) of the room temperature bore (2) and the outer skin (6) of the cryostat exhibits, at the depth l.sub.m from an axial end of the room temperature bore (2) and at least in an angular region about the horizontal cryostat axis (100), minimum separations h.sub.e, h from the inside of the room temperature bore (2) whereby l.sub.m, h.sub.e <35 cm, preferentially<30 cm, and h<50 cm.

Abstract: A gradient coil system for the production of a magnetic transverse gradient field G.sub.x in an NMR tomograph is presented. The main magnetic field B.sub.z is directed along the z-axis, the magnetic transverse gradient field G.sub.x along the x-axis, and the gradient coil system comprises four partial coils (S.sub.1x, S.sub.2x, S.sub.3x, S.sub.4x) each with two current connections (A.sub.1, A.sub.2). The coils are arranged mirror symmetrically with respect to the xy-plane (z=0) and mirror symmetrically with respect to the zy-plane and each partial coil contains only winding sections on an inner and an outer cylinder Z.sub.ix, Z.sub.ax about the z-axis as well as in a radial connecting plane V.sub.+x, V.sub.-x parallel to the xy-plane. The partial coils are configured in such a fashion that the winding sections on the inner and outer cylinder Z.sub.ix, Z.sub.ax are axially further removed from the xy-plane than the corresponding radial connecting planes V.sub.+x, V.sub.-x, and the axial separation d.sub.

Abstract: In an NMR tomograph with superconducting main field coil (10) and large transverse access opening a compensation of inhomogeneities of the static magnetic field without hindering the axial and transverse access to the investigational volume (V) can be effected by the following elements:ferromagnetic homogeneity elements (20) which are arranged on the surface of the room temperature bore on both sides of the transverse access opening;at least one or more (a number p.gtoreq.1) superconducting correction coils (C.sub.1 and C.sub.p) which can be separately supplied with current and which are coaxial to the main field coil (10), whereby each correction coil (C.sub.1 through C.sub.p) comprises at least two partial coils (C.sub.1i, C.sub.1a through C.sub.pi, C.sub.pa), whereby all partial coils of all correction coils (C.sub.1 through C.sub.p) are cylindrical coils coaxial to a common axis (z) having a diameter less than the inner diameter (d.sub.

Abstract: In an NMR tomograph with superconducting main field coil (10) and large transverse access opening a compensation of inhomogeneities of the static magnetic field without hindering the axial and transverse access to the investigational volume (V) can be effected by the following elements:ferromagnetic homogeneity elements (20) which are arranged on the surface of the room temperature bore on both sides of the transverse access opening;at least four superconducting correction coils (C.sub.1 and C.sub.4) which can be separately supplied with current and which are coaxial to the main field coil (10), whereby each correction coil (C.sub.1 through C.sub.4) comprises at least two partial coils (C.sub.1i, C.sub.1a through C.sub.4i, C.sub.4a), whereby all partial coils of all correction coils (C.sub.1 through C.sub.4) are cylindrical coils coaxial to a common axis (z) having a diameter less than the inner diameter (d.sub.a2) of the outer field coil (1a, 1b), whereby in each correction coil one partial coil (C.sub.

Abstract: In an NMR tomography apparatus with a superconducting main-field coil comprising two partial coil systems which are rotationally symmetric about a horizontal central z axis and are arranged mirror-symmetrically with respect to a vertical transverse middle plane E.sub.q and which are accommodated within a two-part cryostat which is symmetric with respect to the transverse middle plane E.sub.q and which comprises two slice-like partial cryostats which are connected to each other through strut-like connecting elements (8) of length g running largely parallel to the central axis z to form the entire cryostat and which exhibit a room temperature bore of diameter d.sub.B running symmetrically about the central z axis, whereby 1.6 g.ltoreq.d.sub.B 2.1 g, precisely three vertical connecting elements (8) are provided for which are arranged asymmetrically with respect to a vertical longitudinal middle plane E.sub.1 and assume angular positions in the ranges 50.degree. to 100.degree., 180.degree. to 230.degree. an 320.

Abstract: A nuclear spin resonance (NMR) measuring device, in particular an NMR tomography apparatus with a preferentially superconducting main field coil which is capable of producing, within a measurement volume whose center is coincident with the origin of a Cartesian coordinate system x, y, z, a homogeneous static magnetic field B.sub.0 in the direction of the z-axis of this coordinate system and with a tesseral gradient coil system for the production of magnetic gradient fields with a largely linear dependence within the measuring volume in a direction perpendicular to the z-axis, whereby the gradient coil system comprises at least four largely identical saddle-type partial coils arranged symmetrically with radial and axial separations from the coordinate origin, the partial coils each exhibiting two electrically conducting segments which run about the z-axis in the azimuthal direction one segment (21) of which has as small a radial separation r.sub.1 and the other segment (22) as large a radial separation r.sub.

Abstract: An apparatus is disclosed for the propulsion of water vehicles. A magnet field as well as an electric field with essentially perpendicular field lines are produced in a pipe through which surrounding water flows. In this manner, a force is exercised upon charge carriers within the surrounding water and this force is used as a propulsion force for the water vehicle. The pipe is surrounded by a solenoid coil which is arranged essentially coaxially to the pipe. A first electrode is arranged essentially along the axis of the pipe and a voltage source is switched between the electrode and the pipe, acting as a second electrode. An Archimedes' screw is arranged in the cylindrical gap between the electrode and the pipe in order to deflect the surrounding water circulating about the axis into an axial direction, or the screw is rotationally rigidly connected to a moving conductor arranged perpendicularly to the direction of the magnet field.

Abstract: In an NMR apparatus with a system of gradient coils for the production of a magnetic field gradient within a measurement volume (1) within a field coil, the transverse gradient coils are constructed unsymmetrically with respect to the z=0 plane dividing the measurement volume (1), however largely mirror symmetric to a x=0 or y=0 plane containing the z axis, and possess only two partial coils (20', 20''; 40', 40'') whose windings each exhibit the same winding direction. The axial gradient coils are cylindrically symmetric with respect to the z axis and totally unsymmetric with respect to the z=0 plane, and consist of at least two partial coils which are arranged on differing sides of z=0 plane, whereby the partial coils on one side largely exhibit the opposite winding direction than the coils on the other side, and whereby the number of coils with a particular winding direction is not equal to the number of coils with the opposite winding direction.

Abstract: In a method for the production of a magnet coil arrangement which can create a predetermined magnet field B and has a minimal inductance L. The magnetic field B to be generated is expanded in spherical harmonics with coefficients C.sub.n,m and a field error .DELTA. B=f.sub.1 (C.sub.n,m) is defined fixing the deviation of the magnet field profile of the coil arrangement to be calculated from the given magnet field B within a volume and, if necessary, further parameters P=f.sub.2 (C.sub.n,m) are predefined, whereby the value of P which is calculated with a particular set of coefficients C.sub.n,m is within predetermined limits. By defining limits for technically relevant parameters and their variation as well as by giving the desired minimum inductance, the procedure achieves a high flexibility in conjunction with independent optimization of the parameters, in particular field errors, minimum inductance and current density oscillations.

Abstract: A superconductive magnet coil arrangement for generating a homogeneous magnetic field in a volume under examination, comprising a magnet coil having two first windings of a superconductive wire which are disposed adjacent the ends of the magnet coil and which are supported on a hollow supporting body, and comprising further at least one additional winding of a superconductive wire which is arranged in the area between the first windings and which is supported by the supporting body, is characterized by the fact that at least one of the additional windings is arranged on a winding core mounted on the supporting body and the fixation securing the winding against axial displacement occupies an area in length of the winding core shorter than the length of the winding arranged on the winding core. It is achieved in this manner that the pressure produced by Lorentz forces in the supporting body is kept off the rest of the winding.

Abstract: Winding arrangements for cryomagnets have a winding of superconducting wire (12) connected in parallel to a winding of normally conducting wire (11) which, in the event of a quench, conducts the operating current and mechanically stabilizes the winding arrangement. Independently of this, the size of such a winding arrangement depends primarily on the tensile forces exerted on the wires and on the modulus of elasticity of the material of the wire. The size of such a winding arrangement is a significant factor in its cost and should therefore be reduced. According to the invention, the winding arrangement has a plurality of groups (17) arranged in radially repetitive layers inside the winding section, in which each winding of superconducting wire surrounds windings of a normally conducting wire and windings of steel wire or of a wire with a high modulus of elasticity.