Abstract: In one embodiment, a superconducting magnet includes: at least one primary superconducting coil configured to generate a primary static magnetic field by a persistent current flowing during a persistent current mode; at least one secondary superconducting coil configured to generate a secondary static magnetic field different from the primary static magnetic field in response to external control; and a static-magnetic-field control switch configured to (i) supply the secondary superconducting coil with part of the persistent current to generate the secondary static magnetic field by being closed in response to the external control during the persistent current mode and (ii) stop energization of the secondary superconducting coil and generation of the secondary static magnetic field by being opened in response to the external control during the persistent current mode.

Abstract: A static magnetic field magnet according to any of embodiments includes: a superconducting coil generating a static magnetic field; and a radiation shield surrounding the superconducting coil. In the static magnetic field magnet, at least a surface on a gradient coil side of the radiation shield includes a peripheral portion that forms multiple concavity and/or convexity. Further, In the static magnetic field magnet, a shape of a cross-section perpendicular to a depth direction of each of the multiple concavity and/or convexity formed by the peripheral portion is polygonal or circular. It is preferable that the peripheral portion is configured to form the multiple concavity and/or convexity in a straight line.

Abstract: In one embodiment, a superconducting magnet includes: at least one set of coil segment including a first coil segment formed of a superconducting wire through which an electric current flows in a forward direction, and a second coil segment formed of the superconducting wire through which an electric current flows in a direction opposite to the forward direction; and at least one intermediate wiring provided between the first coil segment and the second coil segment and configured to connect the first coil segment and the second coil segment without disconnection and change directions of electric currents such that that the electric current flows through the first coil segment in the forward direction and the electric current flows through the second coil segment in a direction opposite to the forward direction.

Abstract: In one embodiment, an MRI apparatus includes: a static magnet provided with a superconducting coil and configured to generate a static magnetic field having static magnetic field distribution in an open space outside the superconducting coil; control circuitry configured to adjust the static magnetic field distribution; and a reconstruction processing circuit configured to generate a magnetic resonance image on the basis of magnetic resonance signals emitted from an object that is at least partially placed in the open space outside the superconducting coil.

Abstract: A static magnetic field magnet according to any of embodiments includes: a vacuum vessel; a radiation shield provided inside the vacuum vessel; a superconducting coil provided inside the radiation shield, the superconducting coil generating a static magnetic field; and a winding frame supporting the superconducting coil and including a heat-generation suppression shield having a surface layer on a gradient coil side and an inner layer on the superconducting coil side. In the static magnetic field magnet, the surface layer and the inner layer are structurally or functionally separated from each other, the surface layer is configured as a layer where an eddy current generated in the winding frame flows, and the inner layer is configured as a layer where an eddy current does not almost flow.

Abstract: Disclosed is a method for producing a Trifluoromethanesulfonic anhydride, which is characterized by that a reaction is conducted while kneading a Trifluoromethanesulfonic acid and diphosphorus pentoxide at a temperature that is 40° C. or higher and is lower than 100° C. by using a kneader-type reactor having a maximum power of 1.0 kW or greater per an actual capacity of 100 L and equipped with at least two-shaft blades, that the Trifluoromethanesulfonic anhydride to be generated is discharged, and that, while the residue in the reactor after the discharge is kneaded at a temperature that is 100° C. or higher and is lower than 140° C., the unreacted Trifluoromethanesulfonic acid is discharged, recovered and reused as the raw material. It is possible by this method to obtain a Trifluoromethanesulfonic anhydride with a high yield.

Abstract: Disclosed is a method for producing a fluoroalkanesulfonic anhydride, which is characterized by that a reaction is conducted while kneading a fluoroalkanesulfonic acid and diphosphorus pentoxide at a temperature that is 40° C. or higher and is lower than 100° C. by using a kneader-type reactor having a maximum power of 1.0 kW or greater per an actual capacity of 100 L and equipped with at least two-shaft blades, that the fluoroalkanesulfonic anhydride to be generated is discharged, and that, while the residue in the reactor after the discharge is kneaded at a temperature that is 100° C. or higher and is lower than 140° C., the unreacted fluoroalkylsulfonic acid is discharged, recovered and reused as the raw material. It is possible by this method to obtain a fluoroalkanesulfonic anhydride with a high yield.

Abstract: A magnetic resonance imaging apparatus includes; a gradient coil that applies a gradient magnetic field to a static magnetic field in which an examined subject is placed; a metal shim with which the gradient coil is provided and that corrects spatial nonuniformity of the static magnetic field; an executing unit that executes an imaging sequence; and a controlling unit that, before execution of the imaging sequence is started, raises the temperature of the metal shim up to a saturation temperature that is to be reached during the execution of the imaging sequence.

Abstract: A magnetic resonance imaging apparatus includes; a gradient coil that applies a gradient magnetic field to a static magnetic field in which an examined subject is placed; a metal shim with which the gradient coil is provided and that corrects spatial nonuniformity of the static magnetic field; an executing unit that executes an imaging sequence; and a controlling unit that, before execution of the imaging sequence is started, raises the temperature of the metal shim up to a saturation temperature that is to be reached during the execution of the imaging sequence.

Abstract: A passive shim coil is disposed in a magnetic resonance imaging (MRI) apparatus for shielding magnetic flux of a gradient magnetic field at an inner circumference side generated by a gradient coil, and is set at an outer circumference side of the gradient coil. The coil body is formed of a portion including a superconducting material and a portion including a non-superconducting material.

Abstract: A passive type shield coil, disposed to a magnetic resonance imaging apparatus, for shielding of a magnetic flux of a gradient magnetic field at an inner circumference side generated by a gradient coil for generating the gradient magnetic field, and set at an outer circumference side of the gradient coil, has a coil body formed of a portion including a superconducting material and a portion including a non-superconducting material.

Abstract: Although magnet coil windings are distributed discontinuously, the distribution of magnetic fields generated actually approaches a desired continuous distribution. The desired continuous distribution is defined analytically, as closely as possible. A system for acquiring magnetic resonance data has a coil segment formed by winding a conductor on a bobbin representing an axial direction. A magnetic field is generated by supplying current into the conductor. Winding positions at which the conductor is wound turn-by-turn on the bobbin are determined in agreement with a specified current step value and sequentially from a winding positioned at an outermost end of the coil segment in the axial direction. Additionally, a shunt element for shunting the current carried turn-by-turn is arranged in the coil segment in relation to a pattern of turns of the coil segment by winding the conductor into a plurality of current flows through a plurality of shunt paths.

Abstract: Solid-borne vibrations and airborne vibrations from a gradient coil unit in an MRI gantry environment are markedly reduced thereby reducing ambient noise occurring due to the vibrations. Support assemblies retain the gradient coil unit in a mechanically-uncoupled or substantially-uncoupled state relative to the magnet by supporting the coil unit at separate positions on the floor (e.g., with anchor bolts rigidly coupling coil support assemblies to the floor). Moreover, the gradient coil unit and at least parts of the support assemblies may be retained in a vacuum space.

Abstract: In a magnetic resonance imaging apparatus, gradient magnetic fields and a radiofrequency magnetic field are applied to a subject placed in a static magnetic field to excite nucleuses and generate magnetic resonance signals. A magnetic resonance image is reconstructed on the basis of the magnetic resonance signals. The gradient magnetic fields are produced by gradient coils. A very high-speed imaging method such as an echo planar method requires shield coils to magnetically shield, to the outside, the magnetic fields generated by the primary coils. It is very difficult to drive the primary coils and the shield coils by one amplifier to raise gradient magnetic fields having a relatively high strength within a short period of time. The primary coils and the shield coils are divided into a plurality of groups, and currents are individually supplied to the plurality of groups to allow to raise the gradient magnetic fields having a relatively high strength within the short period of time.

Abstract: An MRI system is provided for improving the magnetic coupling and positional relationship between gradient coils and shim coils, thus simplifying positioning of the coils (retention of orthogonality), designing an MRI system compactly, and reducing cost. An MRI system comprises a magnet generating a static magnetic field and a gradient coil unit generating a gradient magnetic field superposed on the static magnetic field. The gradient coil unit is formed into a substantially cylindrical shape having an outer circumferential surface, and shields the gradient magnetic field from being leaked out into a radially outer space. The MRI system further comprises a shim coil unit generating a correcting magnetic field homogenizing the static magnetic field. The shim coil unit is mounted on the outer circumferential surface of the gradient coil unit in common serving as a bobbin for the shim coil unit.

Abstract: An upconversion laser material includes a micro-sphere which is doped with an ion of a rare earth element and made of one selected from the group consisting of crystals and glasses. Thus, the micro-sphere achieves the light confinement therein and serves as a resonator. Therefore, the Q-value of the resonator becomes large. With this, it is possible to obtain the upconversion laser oscillation at room temperature.

Abstract: A nuclear magnetic resonance imaging with improved image quality and operation efficiency. It uses an active shield coil with an outer shielding coil having at least two coil turns which are provided on a plurality of separate layers and mutually connected electrically, in order to reduce the heat generation. The eddy current in the shielding coil is reduced by providing a slit portion thereon. The eddy current compensation is achieved by using an appropriate eddy current compensation pulse to minimize a residual eddy current magnetic field within a desired field of view according to a model of a general expression of the residual eddy current magnetic field after the eddy current compensation. The optimum setting of the system parameters for various imaging pulse sequences is achieved for the undetermined gradient coil configuration as well as for the predetermined gradient coil configuration, according to a mathematical model analysis of various imaging pulse sequences.

Abstract: The MR imaging apparatus comprises an RF shield for interposed between the set of gradient coil and the RF coil. The RF shield is a cylinder which longitudinal axis is substantially coincident to the z-axis in which a static magnetical field is applied. The RF shield comprises two conductive sheet-members which are half-cylinder respectively and integrated into one cylinder. The sheet members have a plurality of generally C-shaped conductive loop portions respectively which are defined by nonconductive lines parallel to RF current flow induced therein by the RF coil and a single radial cut line respectively.

Abstract: An optical fiber preform includes a core made from a fluoride glass which is doped with a rare earth, and a cladding surrounding the core. The cladding is made from one of an oxide glass and a fluoroxide glass. The core has a characteristic of amplification at 1.3 .mu.m-band. The cladding does not have absorption at 1.3 .mu.m-band. The preform is useful as a material for a fiber optical amplifier in optical communication systems.

Abstract: In an MR (magnetic resonance) imaging method, not only eddy current field is compensated, but also a gradient field vibrated by a mechanical vibration caused by the eddy current is compensated. The method for imaging a biological body under medical examination by utilizing a magnetic resonance phenomenon under influence of a static magnetic field and a gradient magnetic field to acquire an MR image of a preselected slice portion within the biological body, comprising the steps of: producing a first drive current on which an eddy current field compensating current has been superimposed: producing a vibrating-field compensating current for compensating a gradient field vibrated by the eddy current; and superimposing the vibrating-field compensating current on the first drive current to obtain a second drive current. The second drive current is supplied to a gradient coil assembly for generating a gradient field whose vibrating field component has been compensated.