Magnetron

摘要

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.

主权项

1. A magnetron comprising: a hollow cathode including a filament as an electron emissive part, and an outer sleeve containing a core, the hollow cathode being arranged to apply a high frequency voltage between the outer sleeve and the core to heat the filament; and sleeves of ferrous alloy spaced by a sleeve of insulating material joining the core and the outer sleeve, the ferrous alloy sleeves having magnetic flux induced in them, in use, from the high frequency voltage that heats the filament, and the ferrous alloy sleeves having a conductive surface coating with a resistivity of substantially that of copper or silver.