Hunter R Mcdowell, 28563 Nichols St, Norwood, MA 02062

4207495, Jun 10, 1980

Aug 30, 1978

5/938128

Hunter L. McDowell - Concord MA

The United States of America as represented by the Secretary of the Air
Force - Washington DC

H01J 2534

315 393

Crossed field amplifier collector efficiency is improved by decreasing the ratio of electron velocities to r. f. signal wave velocity at the output end of the amplifier slow wave circuit. In a preferred embodiment of the invention this is accomplished by tapering the sole emitting cathode so as to increase the cathode-slow wave circuit spacing in the output end of the interaction region prior to the collector. Alternatively, an increasing r. f. signal phase velocity taper can be used to provide the required decreased electron velocities to r. f. signal wave velocity ratio.

4608520, Aug 26, 1986

Jul 29, 1983

6/518719

Hunter L. McDowell - Concord MA

Varian Associates, Inc. - Palo Alto CA

H01J 2534

315 393

In a crossed-field amplifier tube, an input section of slow-wave circuit is part of the cathode electrode. An output section of slow-wave circuit is part of the anode electrode. The anode circuit is axially displaced from the cathode circuit in the direction of drift of the electron stream so that a non-propagating section of the anode faces at least a part of the propagating cathode circuit.

4435689, Mar 6, 1984

May 10, 1982

6/376314

Hunter L. McDowell - Concord MA

The United States of America as represented by the Secretary of the Army - Washington DC

H01P 122

333 81A

A broadband attenuator section in a meander line slow wave structure is dlosed for attenuating signals reflected between the output and input of the slow wave structure. The attenuator section comprises a multi-element ceramic support structure intermediate the meander line conductor pattern and the substrate wherein the support elements are comprised of a beryllium oxide-silicon carbide ceramic composition with a taper in the percentage of silicon carbide being provided in the transition region from a loss free section of the slow wave structure to a lossy attenuator section. The taper in percentage involves the use of ceramic support elements arranged in a sequence of 1%, 2% and 5% silicon carbide composition prior to the main attenuator section which is comprised of 10% silicon carbide - 90% beryllium oxide support elements.

6236161, May 22, 2001

Feb 26, 1999

9/259643

Michael L. Tracy - Danvers MA
Carl D. Morrill - Topsfield MA
Hunter L. McDowell - Concord MA

Communications & Power Industries, Inc. - Beverly MA

H01J 2542
H01J 2305

315 393

A crossed-field device such as a crossed-field amplifier or magnetron has a generally peripheral cathode body portion and an anode which cooperates with a crossed magnetic field to maintain emitted electrons on cycloidal and amplify an rf input signal as it travels to an rf outlet. A control electrode positioned generally at a drift region away from the crossed-field amplification region interrupts the sustained electron emission to shut down the device between working cycles, and an auxiliary electrode positioned internally of the cathode diverts electrons into a gap proximally of the control electrode to reduce the control electrode energy requirements. The cathode is carried by a support structure, and the auxiliary electrode may be a rod axially extending in a counter-bore in the support structure. The auxiliary electrode is dc biased and may advantageously operate at anode potential, thereby obviating the need for any additional power source for the auxiliary electrode. Preferably the auxiliary electrode forms an inverted magnetron arrangement with the cathode counterbore and diverts electrons from the active region without creating unwanted rf output signal components.

4465984, Aug 14, 1984

May 10, 1982

6/376315

Hunter L. McDowell - Concord MA

The United States of America as represented by the Secretary of the Army - Washington DC

H01P 122

333 81A

A meander line slow wave structure mounted on ceramic bars for a microwave evice such as an injected beam crossed-field amplifier includes frequency selective attenuator means which will preferentially attenuate waves at frequencies near and within the stopband of the slow wave structure by the placement of side absorber bars of attenuating material adjacent to the outer side surfaces of a plurality of meander line finger segments. The frequency selective absorber material, in its preferred form, comprises a beryllia and silicon carbide ceramic composition which additionally adapted to accommodate metallic absorber top plates, nichrome films, and slotted side ring configurations.

4342632, Aug 3, 1982

May 1, 1981

6/259873

Werner F. Heim - Swampscott MA
Hunter L. McDowell - Concord MA

The United States of America as represented by the Secretary of the Army - Washington DC

C23C 1500

204192EC

A ceramic substrate is metallized by a method including the steps of: (A) chemically cleaning the substrate, (B) sputter etching the chemically cleaned substrate, (C) sputtering a chromium layer of about 200 angstroms in thickness onto substrate, (D) sputtering a molybdenum layer of about 3500 angstroms in thickness onto the chromium layer, (E) sputtering a copper layer of about 25,000 angstroms in thickness onto the molybdenum layer, (F) firing the coated substrate in dry hydrogen at about 1000. degree. C. for about 10 minutes, (G) plating a copper-silver brazing alloy of about 0. 0003 inch in thickness onto the copper layer, and (H) firing in dry hydrogen at about 700. degree. C. for about 10 minutes.