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: 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: A method and an apparatus for predicting the future occurrence of earthquakes continuously measures a physical parameter of the earth's crust by means of magnetic spin resonance measurements to develop an alarm signal. When the value of the alarm signal exceeds a threshold value, an alarm is generated.

Abstract: A method and an apparatus are disclosed serving to localize proton-poor objects situated in aqueous surroundings, in particular to localize submarines or sea mines in an ocean or an inland water. By using a nuclear magnetic proton resonance technique, a magnetic disturbance caused by the proton-poor object in relation to its proton-rich aqueous surroundings is detected. The apparatus comprises at least one transmission coil for exciting the nuclear resonance by means of an alternating electromagnetic field and comprises detection means for detecting nuclear magnetic resonance signals. The transmission coil generates conditions in the aqueous surroundings in which water proton nuclear magnetic resonance occurs in a volume region of more than 50 cubic meters, preferably considerably more than 1000 cubic meters of water. The volume region is monitored for the presence of nuclear magnetic resonance signals and a predetermined decrease in such resonance signals is detected.

Abstract: A method and an apparatus for propelling water vehicles in surrounding water are disclosed. The water has carriers of electrical charge. For propelling the water vehicle, the latter is provided with an elongate pipe being immersed in the water for allowing the water to flow therethrough along a longitudinal axis thereof. An electric field (E) is generated within the pipe with electric field lines extending radially with respect to the longitudinal axis. Further, a magnetic field is also generated within the pipe, the magnetic field having field lines extending circumferentially about the longitudinal axis. Thereby, a force (F) is exerted upon the charge carriers by simultaneous action of the electric field (E) and the magnetic field (B) on the charge carriers. The force (F) is directed parallel to the longitudinal axis to thereby propel the water vehicle.

Abstract: A method and a submarine are disclosed influencing an acoustic source emitting an acoustig signal having a first frequency spectrum with at least one intensity maximum. In order to make detection of the frequency spectrum by means of passive acoustic locating systems more difficult, the first frequency spectrum is stochastically modulated by influencing the acoustic source.

Abstract: An electron beam x-ray computer tomography scanner is improved so that a compact, tiltable configuration without mechanical motion is achieved. By introducing the electron beam in a direction which is largely parallel rather than perpendicular to the scan plane, the long large diameter evacuated electron beam pipe of prior art is eliminated. As a result, the scan system according to the invention enjoys compact dimensions compared to those of prior art, and free access to the scan region from both the front and back of the scanner is possible.

Abstract: An X-ray computer tomography system with a stationary ring anode and a plurality of stationary electron sources for the construction of fast scan images from the inside of an object is improved in such a way that there is free access from both sides of the scan region, that the gantry unit can be tilted, and that the image quality which can be achieved is comparable to that of conventional tomography systems with mechanical motion of the anode. A plurality of electron sources are configured in proximity to the ring anode on a stationary ring, with each source being capable of sweeping its respective electron beam over a portion of the anode ring.

Abstract: An X-ray computer tomography system with a ring anode and substantially without mechanically moving parts for the production of fast image slices from the inside of an object is improved in such a way that a detector ring is comprised of two adjacent parallel partial detector rings of substantially equal size, whereby the detector ring is arranged within and coplanar to the anode ring. The two partial rings of the detector ring are displaced in a direction largely pependicular to the scan slice so that a ring-shaped detector ring gap is formed between them through which the fan beam coming from the focal spot on the anode passes.

Abstract: A magnet system to generate a static, uniform magnetic field in the examination chamber of a nuclear spin tomograph has a pair of outer field coils (1a, 1b) arranged on a common axis (a) at a mutual axial distance (g.sub.1) and a pair of inner field coils (2a, 2b) coaxial with the outer ones which are also equal to each other, in which both pairs of coils are arranged symmetrically to a central plane (E) perpendicular to the common axis (a). The axial distance (g.sub.1) between the outer field coils (1a and 1b) is 40 to 60% of their inside diameter (da.sub.2). The axial distance (g.sub.2) between the inner field coils (2a and 2b) is, with a maximum deviation of 15%, equal to that (g.sub.1) between the outer coils (1a and 1b). The magnet system forms an almost eight-order coil system and there is at least one transverse access aperture running across the direction of the uniform magnetic field and between the inner field coils (2a, 2b).

Abstract: A method for operating submerged submarines and a submarine are disclosed which are used to camouflage submerged submarines which, while submerged and travelling, draw a trail of heated cooling water behind themselves. In order to reduce the risk of detection of such submerged submarines by means of heat-sensitive detectors, either the density of the heated cooling water is increased through the introduction of additives, or, the heated cooling water is brought, by mechanical means, to a depth far below the submarine for preventing heated-up cooling water to rise up to the sea surface.

Abstract: An underwater vehicle is disclosed being equipped with a passive optical observation system. The underwater vehicle has an observation window at its disposal which exhibits a diameter in the range from 0.3 to 3.0 m and a curved surface. In order to increase the sensitivity of the passive optical observation system and the ability to detect distant objects, the observation window is part of the passive optical observation system. The entrance pupil of the observation system exhibits a diameter in excess of 0.1 m.

Abstract: A method and an apparatus are disclosed serving to minimize acoustic emission of submerged submarines. Moving mechanical elements in an inner region give off vibrations onto an outer hull via a vibration transmission path. The vibrations are damped with damping means in the vibration transmission path. The damping means is configured as an evacuated intermediate space and is inserted in the vibration transmission path.

Abstract: A method and an apparatus are disclosed serving to reduce acoustic emission from submerged submarines in which vibrations from moving mechanical elements within an inner region are transmitted to an outer hull via a vibration transmission path. For decoupling the outer hull as completely as possible from the moving mechanical elements, for example periodically moving nuclear reactor control rods, the vibrations are actively damped. Means are provided for ascertaining the motion of the mechanical elements relative to the outer hull and for superimposing upon said motion of counter-motion of opposite direction.

Abstract: A cavity resonator serves to generate magnetic dipole transitions in a sample, for instance for carrying out electron spin resonance measurements. The natural frequency of the cavity resonator (10) is influenced by a reduction in length of the E flux lines. To this end, conductive areas (20) are arranged at the points where the E flux lines are encountered. This results in an increase of the space factor, related to an unchanged specimen volume, and thus in an improvement of the measuring sensitivity.

Abstract: An electromagnet for producing the constant magnetic field required in NMR tomography comprises a coil system (1, 2, 3, 4) of the Helmholtz double coil type. The coil system is enclosed in, and supported by, a stable cylindrical shell (5). The influence exerted by the cylindrical shell (5) on the homogeneity of the magnetic field, which is generated by the coil system in an accessible interior space defined by it and suitable to receive the body to be examined, is compensated by the particular dimensioning of the field and error coils (1, 2, 3, 4). The cylindrical shell (5) is best made of a ferromagnetic material having low electric conductivity and is constructed of a plurality of axially serially disposed annular discs (6) which are preferably divided into sectors.

Abstract: A coupling arrangement for a cavity resonator (10), in particular for measuring the magnetic resonance of a sample (17) located within the cavity resonator (10) comprises a loop (14) for supplying a radio frequency signal to the cavity resonator (10) and exciting in the latter a specific mode of oscillation. For optimizing the coupling of the radio frequency signal, mechanical means are provided, preferably in the form of an axially adjustable screw (16), which permit the surface of the loop (14) to be varied mechanically, and the loop (14) is capacitively coupled with the resonator housing.

Abstract: An electromagnet for producing the constant magnetic field required for use in NMR tomography consists of a cylindrical field coil and a stable cylindrical shell made of iron encompassing and simultaneously supporting the coil. The field coil may comprise constituent coils, including error coils, and is capable of producing an at least approximately homogeneous magnetic field within the space defined by the field coil for receiving the object to be examined. Due to the strictly symmetric geometry of the coil assembly, the homogeneity of the magnetic field is not adversely affected by temperature fluctuations, even if the dimensions of the apparatus are such that the coil will admit a human body.