Litton Systems, Inc.

Cabot Corporation

Cadot Corporation

Todd R Gattuso

Steven R Reznek

Kenneth C Koehlert

Joseph Albert Senecal

Matthew Neville

A cathode heater includes a patterned conductor embedded within a dielectric substrate. The ceramic substrate has a pair of conductors over the respective surfaces thereof to provide electrical contact for the heater. To assemble the substrates having the conductors, the substrates and printed conductive patterns are fired to provide a composite multi-layer ceramic heater which can be used to heat cathode electrodes in microwave tubes such as travelling wave tubes.

Cathode heater and cathode assembly for microwave power tubes

The present invention is a method of producing single, unaggregated magnetic iron oxide particles. An iron or iron and divalent metal halide feed solution is kinetically atomized into a high velocity flame. The feed solution is vaporized and held in a reactor at a temperature and partial pressure of an oxidizing phase sufficient to form either ferrous oxide or magnetite particles. The iron or iron and divalent metal halide vapor reacts with the oxidizing phase vapor and converts to either ferrous oxide vapor or magnetite vapor. Since the vapor phase is beyond equilibrium concentration ferrous oxide or magnetite particles precipitate from the vapor phase. Quenching of the magnetite particles at an enhanced rate to less than 500.degree. C. in a reducing atmosphere renders magnetite and in a oxidizing atmosphere renders maghemite. Quenching of the ferrous oxide particles in a non-oxidizing atmosphere produces magnetite particles.

High temperature process for making fine magnetic particles

A method for producing fine magnetic particles having the barium or strotium ferrite M-phase crystal structure. An iron and alkaline earth metal halide feed solution is vaporized to form a precursor and oxidizing vapor phase. The precursor and hydrolyzing or oxidizing vapor phases are held in a reactor at a temperature sufficient to effect vaporization of the feed solution yet which is below the melting point of the desired M-phase crystal structure. Small iron oxide particles precipitate from the vapor phase and alkaline earth oxides thereafter. The alkaline earth oxide particles diffuse into the iron oxide particles to form the desired M-phase structure. When the desired width and thickness of the M-phase crystal platelets is achieved, the M-phase particles are cooled by quenching. Composition of the feed solution may be modified by substituting divalent metal halides for the alkaline earth metal halide or by substituting trivalent halides or a combination of a divalent metal halide and either a penta or quatravalent metal halide for the ferric halide.

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Boston, MA, United States of America

Todd R Gattuso