E2v Technologies (uk) Limited

English Electric Valve Company Limited

Teledyne UK Limited

E2v Technologies Limited

David Bernard Fox

Robert Richardson

Stephen Mark Iskander

Timothy Peter Fox

Scott Williams

A high power electron tube, such as a magnetron, has the disadvantage that, to reduce the chances of the ceramic RF window failing in use, the manufacturing step entails a prolonged ageing period of powering the magnetron at low power on test, in order to drive any absorbed gases out of the RF window. According to the invention, the RF windowis internally glazed (), which makes it possible to avoid the ageing period.

Electron tube

A cathode of a magnetron having a radial extension to accommodate the cathode terminals is supported by arms which have a greater diameter over the region in which they are supported in the glass thimble than over the region of the free ends. This shifts any vibrations to a higher frequency band, which is less liable to be excited in the event the magnetron is moved rapidly as in a linac used for radiotherapy purposes.

Magnetron

A magnetron has an anode and a cathode. The cathode includes two parts joined by sleeves of ferrous alloy spaced by a sleeve of insulating material. The ferrous alloy sleeves are adapted to be connected to opposite poles of a power supply for heating the cathode. A high frequency power supply is used to heat the cathode. The ferrous alloy sleeves have a surface coating of conductive material. The currents induced by the magnetic field generated by the high frequency currents of the power supply are largely confined to the conductive coating due to the skin effect, avoiding the heating of and losses in the ferrous alloy itself which would otherwise ensue.

A high voltage switching apparatus delivers kV pulses to a load such as a magnetron. The switching apparatus comprises a switching stack surrounded by capacitors and both arranged within a housing. Lt power is supplied to the stack, e.g. for control electronics, by magnetic coupling across a non-conducting wall of the housing. Annular inserts are arranged on either side of the wall. Each insert receives a transformer core and winding. The bottom surfaces of the inserts carry a conductive coating to minimise electric stresses. Ht power is also supplied through the wall.

Galvanically isolated delivery of power to high voltage circuits parts

A directly heated cathode comprises a metal tube having a filling of powdered metal which extends beyond the tube and in which is embedded an electrical wire which is coaxial and extensive with said the outer tube over part of its length. The electrical wire is coated with insulating material which is normally alumina. The tube, the metal powder filling and the wire are sintered together, giving a relatively robust structure.

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Chelmsford, United Kingdom

David Bernard Fox