Hitachi, Ltd.

Nippon Telegraph and Telephone Corporation

Hitachi Instrument Engineering Co., Ltd.

Takao Takahashi

Goh Miyajima

Manabu Matsumoto

Takashi Ikeguchi

Tadasi Sonobe

Shinjiro Ueda

Toshiaki Kobari

Tuyosi Shudo

Mamoru Katane

Shohei Suzuki

Toa Hayasaka

Toyoki Kitayama

Takehiko Konno

Apparatus for cancelling magnetic fields for cancelling a leakage magnetic field from a static magnetic field generation assembly are disposed outside the static magnetic field generation assembly. A magnetic shield made of a magnetic substance is disposed between the static magnetic field generating assembly and the cancelling magnetic field apparatus. The cancelling magnetic field generation apparatus is of a cryostatless type.

Magnetic field generator

A magnetic field gradient coil system for use in a magnetic resonance imaging apparatus forming a magnetic field gradient in a direction of a Z-axis of an X, Y, Z orthogonal coordinate system having its origin at a selected position in the imaging apparatus comprises one pair of first coils and one pair of second coils having their centers on the Z-axis and having the same radius, the coils of each coil pair disposed symmetrically with respect to an XY plane including the origin, the coils of the second coil pair disposed more distant from the origin than the coils of the first coil pair, the coils of the first and second coil pairs disposed on one side of the origin supplied with current in the same direction, the coils disposed on the other side of the origin supplied with current opposite to the direction of current in the coils on the one side of the origin, each of the coils of the first coil pair disposed where the value of the Z-axis magnetic field component of first order at a selected position on the Z-axis becomes substantially maximum, and the ampere-turn and position of each of the coils of the second coil pair selected so that, at the selected position, the Z-axis magnetic field components of third and fifth orders provided by the second coil pair have values which can substantially cancel the Z-axis magnetic field components of third and fifth orders provided by the first coil pair.

Magnetic field gradient coil system

Synchrotron radiation is generated when a base of charged particles is bent by a bending magnet. The synchrotron radiation passes down a lead-out duct as the total number of pumps is limited by the size of the apparatus and many pumps are needed in order to achieve a good vacuum. An ion pump has a main magnetic field, normally generated by a magnet of the ion pump which controls the behavior of the electrons in the ion pump. However, the leakage magnetic field of the bending magnet affects the ion pump, and therefore the ion pump is arranged so that its main magnetic field is aligned with the leakage magnetic field at the ion pump, or at least with a main component thereof. In this way, the effect of the leakage magnetic field on the ion pump is reduced. Indeed, it is possible to use the leakage magnetic field as the main magnetic field of the ion pump.

Synchrotron radiation generation apparatus

In a permanent magnet device, a pair of pole pieces of a ferromagnetic material are disposed opposite to each other, and, in order to generate a homogeneous magnetic field in a gap space between the pole pieces, a pair of members of a permanent magnet material magnetized in a direction substantially orthogonal to the direction of the magnetic field and also magnetized in directions opposite to each other in themselves are disposed adjacent to the pole pieces and symmetrical with each other respectively.

Permanent magnet device

Growing community of inventors

Hitachi, Japan

Takao Takahashi