Abstract: A current detecting sensor includes parallel flat plates opposed in a substantially U-shape in cross-section. Since the flat plates are opposed to each other, the current detecting sensor has reduced inductance, significantly decreasing frequency dependency of outputs from detection terminals.

Abstract: An object is to obtain long-term reliability of an electric connection in a power semiconductor module. In a power semiconductor module, the main circuit interconnection directly connected to a power semiconductor chip (3) is formed of a busbar (6) and the power semiconductor chip (3) and the busbar electrode (6a) of the busbar (6) are electrically connected through a conductive resin (12). A member (13) having lower thermal expansion than the busbar electrode (6a) is joined to the busbar electrode (6a) in the part adjacent to said power semiconductor chip (3).

Abstract: A gyrotron system comprises an electron gun that produces an electron beam, a magnetic field generating unit comprising a permanent magnet and two electromagnets and capable of generating an axial magnetic field that drives electrons emitted from the electron gun for revolving motion, a cavity resonator that causes cyclotron resonance maser interaction between the revolving electrons and a high-frequency electromagnetic field resonating in a natural mode, a collector for collecting the electron beam traveled through the cavity resonator, and an output window through which a high-frequency wave produced by the cyclotron resonance maser interaction propagates. The gyrotron system can be fabricated at a comparatively low cost, is easy to operate, has a comparatively small size and is capable of operating at a comparatively low running cost.

Abstract: The invention provides a cylindrical permanent magnet unit suitable for application to gyrotrons. Essentially the magnet unit consists of two cylindrical permanent magnets which are coaxially aligned, and there is a space between the two cylindrical magnets. Each of the two cylindrical magnet is a coaxially juxtaposed assembly of a plurality of ring-like permanent magnets, and each ring-like magnet is constructed of a plurality of permanent magnet segments. In one of the two cylindrical magnets every ring-like permanent magnet is magnetized in radial directions from the inside toward the outside, and in the other every ring-like permanent magnet is magnetized in radial directions from the outside toward the inside. In the bore of the cylindrical magnet unit the magnetic field is in the direction of the longitudinal center axis of the bore.