Abstract: A filament assembly for use in an x-ray emitting device or other filament-containing device is disclosed. In one embodiment, an x-ray tube is disclosed, including a vacuum enclosure that houses both an anode having a target surface, and a cathode positioned with respect to the anode. The cathode includes a filament assembly for emitting a beam of electrons during tube operation. The filament assembly comprises a heat sink and a plurality of filament segments. The filament segments are configured for simultaneous emission of an electron beam for impingement on the target surface of the anode, and are electrically connected in series. Each filament segment includes first and second end portions that are thermally connected to the heat sink, and a central portion that can be configured with a modified work function for preferential electron emission.

Abstract: A filament assembly for use in an x-ray emitting device or other filament-containing device is disclosed. In one embodiment, an x-ray tube is disclosed, including a vacuum enclosure that houses both an anode having a target surface, and a cathode positioned with respect to the anode. The cathode includes a filament assembly for emitting a beam of electrons during tube operation. The filament assembly comprises a heat sink and a plurality of filament segments. The filament segments are configured for simultaneous emission of an electron beam for impingement on the target surface of the anode, and are electrically connected in series. Each filament segment includes first and second end portions that are thermally connected to the heat sink, and a central portion that can be configured with a modified work function for preferential electron emission.

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: In electron beam discharge tubes breakdown in the form of a gaseous arc can occur. An improved form of electrode which protects an insulating support against local high-stress fields is described. The electrode has a conductive shield extending to the other side of an interface between the electrode and the insulating support. A mechanism, the "single surface multipactor effect," which could cause the breakdown is also described.