Hitachi, Ltd.

Takeo Nemoto

Norihide Saho

Hisanao Ogata

Hiroyuki Watanabe

Mitsuru Saeki

Susumu Harada

Yasuomi Yagi

Taisei Uede

Takahiro Daikoku

Ken Takahashi

Isao Nakajima

Katsuaki Kikuchi

Ryuya Ando

Shinji Yamamoto

Kazumasa Fujioka

Yoshinori Hakuraku

Shinichi Shimode

Teruhiro Takizawa

Yasuo Yamashita

Masayuki Otsuka

Sachihiro Yoshimatsu

Tuyosi Shudo

Shintaro Sado

Yoichi Ono

Kazuya Higeta

Kozo Matsumoto

Tadashi Takada

Tohsuke Hirata

Yoshihide Shizuoka

Provided superconducting magnet allowing the temperature of the permanent current switch to be quickly lowered and the excitation time of the superconducting magnet to be shortened, an MRI apparatus and an NMR apparatus having the superconducting magnet. A superconducting magnet structure is disclosed in which a superconducting coilis connected to a second stageof a refrigerating unitthrough a low-temperature-side highly thermal conductorand a permanent current switchcovered by a highly thermal conductoris connected to a second stageof the refrigerating unitthrough a heat insulatorand a low-temperature-side highly thermal conductorGas is supplied from a gas bottledisposed outside a vacuum vesselto a condenserin a thermal shieldIn addition, a first pipethat supplies condensate liquid to a liquid storage chamberis provided. The liquid storage chamberis disposed at an upper portion of the permanent current switchA check valveis connected to the first pipe

Superconducting magnet, MRI apparatus and NMR apparatus

An object of the present invention is to provide a MRI superconductive magnet enables sharp images representing patients' health states to be produced. [Means for Achieving the Object] A MRI superconductive magnet having a superconductive coil, a liquid vessel of liquid helium used to cool the superconductive coil, a heat shield to accommodate the liquid vessel therein, a vacuum chamber to accommodate the heat shield therein, a load supporting body for supporting the superconductive coil from the vacuum chamber and securing the superconductive coil, a second cold part of a multi-stage refrigerator for cooling a heat exchanger to condense evaporated helium gas, and a first cold part of the multi-stage refrigerator for cooling the heat shield, wherein a magnetic shield is provided from the first cold part of the multi-stage refrigerator to an outer periphery of the second cold part of the multi-stage refrigerator.

MRI superconductive magnet

The invention utilizes a characteristic of superconducting coils that they have high thermal conductivity in a direction of winding. A part of the superconducting coils is thermally connected with liquid helium through thermal anchors so that the part of the superconducting coils can be cooled to the liquid helium temperature. This cooling structure maintains thermal stability of a superconducting MRI magnet even in a condition that a refrigerator stops for a certain period of time, and reduces a manufacturing cost of the superconducting magnet.

Superconducting magnet for MRI

In a super conductive magnet apparatus comprising a super conductive coil, a helium containing volume for containing therein liquid helium to keep a temperature of the super conductive coil low, and a vacuum vessel containing therein the super conductive coil and the helium containing volume, the super conductive magnet apparatus further comprises a support body on which the super conductive coil is arranged, a container cover forming the helium containing volume with the support body in such a manner that a thermal energy is capable of being transmitted between the super conductive coil and the liquid helium, and a connecting member connecting the support body to the vacuum vessel so that the support body is supported through the connecting member on the vacuum vessel.

Super conductive magnet apparatus

A vacuum vessel has a member to be cooled to a low operating temperature inside the vacuum vessel and a main cooling circuit having fluid for cooling the member to operating temperature. The main cooling circuit has first fluid refrigerating means located at the vacuum vessel. To achieve rapid cooling, there is a pre-cooling circuit having the fluid for pre-cooling the member towards the operating temperature. The pre-cooling circuit has second fluid refrigerating means operating independently of the first fluid refrigerating means. The pre-cooling circuit cools the main cooling circuit, prior to operation of the main cooling circuit, by passage of the fluid from the pre-cooling circuit into the main cooling circuit. A heat shield cooling circuit for cooling a heat shield cools the second fluid refrigerating means of the pre-cooling circuit.

Vacuum vessel having a cooled member

In a cryostat with a liquefaction refrigerator, an object to be cooled, as well as a low-temperature end of the liquefaction refrigerator for cooling the object to be cooled, is contained in a thermally-insulated vessel. The liquefaction refrigerator comprises a cooler and a refrigerator, and the cooler comprises, as main components, a heat exchanger and an expansion valve. The refrigerator includes a mechanically-operated cold-generating device. Within a vacuum vessel in the cryostat, the cooler and the refrigerator are thermally connected together by a releasable thermally-conductive member. Since the refrigerator and the cooler are separate from each other, they can be overhauled independently of each other, and the cooler can be of a compact and lightweight design. Therefore, there can be provided the cryostat which is low in running cost, and has an excellent cooling performance.

Cryostat with liquefaction refrigerator

A magnetically shielded cryostat, e.g. in a MRI imaging apparatus, has a heat-insulating tank having an outer wall. A magnetic shield is spaced from the tank, covers at least partly the outer wall of the tank and is not supported by the tank. A refrigerator having a cooled member extends into the tank. In order to avoid direct transmission of vibration of the refrigerator to a center region of the shield, the refrigerator is supported on the magnetic shield by at least one elongate support member connected to the shield only at or close to the ends of the shield.

Cryostat and nuclear magnetic resonance imaging apparatus including a

A compressor unit in which the oil separated by a plurality of oil separators to a gas suction side pipe of the previous stage oil separator which contains gas whose oil concentration is higher than that of the gas from which oil has been separated, with the separated oil being returned to a compressor. The plurality of separators enables a simplification of the arrangement of the oil returning pipe, a prevention in a reduction in the discharge flow rate of the compressor, and reduction in space required for the separators.

Compressor unit and separator therefor

A refrigerator having a pressurizing device, a coldness generating device for generating coldness by expanding a portion of operating fluid which has been pressurized by the pressurizing device and a fluid passage through which the operating fluid is, via a device to be cooled, again circulated to the pressurizing device after the residual portion of the operating fluid has been cooled by the coldness generating device. A regenerator type heat exchanger is disposed in the fluid passage through which the operating fluid passes, and a switch device switches the flow of the operating fluid in the fluid passage to the reverse direction at a predetermined time period.

Gas swing type refrigerator

A cryopump for effecting a cooling operation by a freezing medium such as liquid helium. A plurality of radiation-heat shield plates for protecting cryopanels against an external heat radiation are provided in opposed relation to a gas inlet of the cryopump. Particularly, a plurality of groups of such radiation-heat shield plates are provided in such a manner that the radiation-heat shield plates of each group are arranged in a multi-stage manner in registry with one another in the direction of the depth of the cryopump and are disposed in parallel relation to one another. Each of the cryopanels is disposed adjacent to a rear surface of respective radiation-heat shield plates facing away from the gas inlet. With this construction, the gas molecules reflected by those radiation-heat shield plates and by a rear wall of the cryopump, are less liable to reach the gas inlet, and tend to be condensed at an increased rate on those cryopanels.

Cryopump

A nuclear magnetic resonance apparatus in accordance with the present invention includes ferro-magnetic field generation means and gradient field generation means and fixes the gradient field generation means at a predetermined position inside a cylindrical space by a support member. An elastic member is interposed between the support member and the gradient field generation means, and means for improving rigidity of the gradient field generation means, such as another support member and a fastening jig of the gradient field generation means, is disposed and fixed to the elastic member described above. In the manner image quality can be improved and noise can be reduced.

Nuclear magnetic resonance apparatus

A cryostat comprises a vacuum vessel, a partition wall for air-tightly separating the vacuum vessel into a first vacuum chamber and a second vacuum chamber, thermal shield tubes encapsulated within the first vacuum chamber, a cooler encapsulated within the thermal shield for containing therein a body to be cooled and cryogen for cooling the body to be cooled, a cryo-cooler disposed outside of the vacuum vessel, which has a cooling portion disposed within the second vacuum chamber, a heat transfer passage along which heat is transferred from the thermal shield tubes to the cooling portion of the cryo-cooler through a part of the partition wall, at least two openings provided in the second vacuum chamber, through which the second vacuum chamber is capable of being opened to atmosphere, and covers each detachably mounted to the respective openings for maintaining the second vacuum chamber at a vacuum condition, on which covers the cryo-cooler is mounted.

Cryostat with cryo-cooler

In a cryostat with a refrigerator containing a superconductive magnet, in which a material to be cooled and a low temperature end of the refrigerator for cooling the to-be-cooled material are disposed within a heat-insulating tank, the refrigerator is connected in unison with a part of a structural member other than the heat-insulating tank by a rigid coupling member. Accordingly, a heat portion of the refrigerator is tightly coupled to a magnetic shield member having a large mass and is connected to a vacuum container through bellows. The end portion of the refrigerator is formed in unison with heat shield sleeves and/or the heat shield tank through heat-conductive material having elasticity. Also, in order to prevent the leakage of the sound or noise from the heat portion, a sound-insulating cover is provided also for passages connecting to the head portion and is fixed to the magnetic shield member.

Cryostat with refrigerator containing superconductive magnet

A superconducting device including a superconducting coil is suitable for use in a nuclear magnetic resonance computer tomography apparatus which requires a highly-uniform, highly-stable magnetostatic field. However, a serious problem arises when a large-sized superconducting coil is to be installed in a small room of a hospital or the like. A superconducting device capable of solving this problem is disclosed in which a very low temperature vessel having the form of a cylinder contains a superconducting coil in a state that the superconducting coil is immersed in a very low temperature coolant, and very low temperature coolant inlet port communicating the very low temperature vessel for introducing the very low temperature coolant into the very low temperature vessel is provided along a radial direction perpendicular to the horizontal center axis of the superconducting device and inclined at a desired angle with a vertical direction. The above superconducting device can be installed in a small room of a hospital, and makes easy a very low temperature coolant introducing operation.

Superconducting device

A thermal head is provided with a heat accumulating member disposed on a substrate, a plurality of heating resistors juxtaposed on the heat accumulating member in a manner to be spaced from each other, electrodes for supplying electric power to the heating resistors, and a protective member for preventing oxidation and wear of the heating resistors and the electrodes, these constituents being formed as layers. When the electric power is supplied to the electrodes, heat is generated by a heating portion of the heating resistor corresponding to the electrodes, and it is transmitted to a head surface via a thermally conductive member disposed in a printing dot portion of the protective member. The heat from the printing dot portion is used for effecting printing on a medium to-be-recorded through a thermosensitive sheet which lies in contact with the head surface.

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Ibaraki, Japan

Takeo Nemoto