Yehoshua D Agassi

US Patent:

6961597, Nov 1, 2005

Filed:

Jul 1, 2003

Appl. No.:

10/609866

Inventors:

Yehoshua Dan Agassi - Silver Spring MD, US

Assignee:

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

International Classification:

H01B012/00
H01F006/00
H01L039/00
H01P001/00

US Classification:

505230, 505202, 505210, 505410, 505430, 333 99 S

Abstract:

Based on its superconductive properties relating to “nonlineanty,” a conventional HTS strip is divisible into three “domains,” namely, a medial domain and two lateral domains. The nonlinearity associated with the conventional strip's medial domain is considerably greater than that which is associated with its lateral domains. Similarly divisible into a medial domain and two lateral domains, the present invention's HTS strip uniquely exploits these physical distinctions by causing more (e. g. , most) of the current that it conducts to be conducted by its lateral domains. Various inventive designs accomplish this through narrowing or interruption/punctuation (e. g. , via holes and/or trenches) or degradation, or some combination thereof, of the medial domain. By thus “re-proportioning” current conduction as compared with a conventional strip, an inventive strip succeeds in “re-proportioning” the associated nonlinearities. Consequently, the total nonlinearity associated with an inventive strip is significantly lower than that which is associated with a conventional strip.

US Patent:

7521708, Apr 21, 2009

Filed:

Dec 29, 2004

Appl. No.:

11/025820

Inventors:

Yehoshua Dan Agassi - Silver Spring MD, US

Assignee:

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

International Classification:

H01L 29/06

US Classification:

257 31, 257 30, 257 38

Abstract:

More sensitive (especially due to reduced interference of flux noise) than a conventional SQUID, an inventive SQUID's major component is a hollow cylindric structure comprising one or more annular Josephson junctions. Each annular Josephson junction is defined by two superconductive annuli and an interposed non-superconductive annulus. Inventive practice is variable, e. g. , in terms of number and/or spacing of Josephson junctions, and/or as having one or more shunts connecting two or more Josephson junctions, and/or as having one or more vortices each threaded through a Josephson junction. The inventive cylindric structure is positioned proximate a magnetic field of interest so that the latter is aligned with the longitudinal axis of the former. Electrical current is transmitted through the inventive cylindric structure in the longitudinal-axial direction so that, based on the quantum interference associated with the one or more annular Josephson junctions, the measured output voltage is indicative of the magnetic field.

US Patent:

7761125, Jul 20, 2010

Filed:

Sep 27, 2005

Appl. No.:

11/240786

Inventors:

Yehoshua Dan Agassi - Silver Spring MD, US
Daniel E. Oates - Belmont MA, US

Assignee:

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

International Classification:

H01B 12/02
H01P 1/00

US Classification:

505210, 505220, 505230, 505700, 505701, 505866, 333 99 S, 333238

Abstract:

Intermodulation distortion (IMD) is known to be an impediment to progress in superconductor-based filter technology. The present invention's methodology for reducing IMD can open doors to heretofore unseen practical applications involving high temperature superconductor (HTS) filters. Typical inventive practice includes (a) increasing the thickness d, and/or (b) changing the operation temperature T, of the filter's HTS film. The film's thickness d is increased in such a way as to decrease the IMD power Pin accordance with the material-independent proportionate relationshipP∝1/d. The film's operation temperature T is bettered or optimized in accordance with the material-independent proportionate relationshipP∝(λ(T))(K(T))/(Δ(T)),and further in accordance with three individual material-dependent relationships, namely, between operation temperature T and each of linear penetration depth λ, gap maximum Δ, and kernel K. Some inventive embodiments include oxygen overdoping of the film as an additional/alternative IMD-reductive measure.

US Patent:

8391937, Mar 5, 2013

Filed:

Mar 5, 2008

Appl. No.:

12/079084

Inventors:

Yehoshua Dan Agassi - Silver Spring MD, US
Daniel E. Oates - Belmont MA, US

Assignee:

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

International Classification:

H01P 1/203

US Classification:

505210

Abstract:

As typically embodied, the present invention's RF cavity device comprises a rigid frame and plural flexible tiles. The frame includes walls of at least substantially uniform thicknesses that describe a hollow pillbox shape. The tiles are at least approximately equally thick, each tile being of at least substantially uniform thickness. Each tile includes a flexible metallic substrate and an HTS coating atop the substrate. The tiles are attached via their corresponding substrates to the inside wall surfaces of the frame so that their corresponding HTS coatings are interiorly exposed. The attached tiles flexibly conform to curved surface areas, are snugly set with narrow seams therebetween, and cover at least approximately the entirety of the frame's inside wall surfaces. A filler material is applied to the seams. The resultant tile configuration is characterized by at least approximate levelness of the exposed HTS coating surfaces and the filled seams.

US Patent:

8412292, Apr 2, 2013

Filed:

Jul 16, 2010

Appl. No.:

12/837544

Inventors:

Yehoshua Dan Agassi - Silver Spring MD, US
Daniel E. Oates - Belmont MA, US

Assignee:

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

International Classification:

H01L 39/24
H01P 1/00

US Classification:

505210, 505330, 505701, 505866, 333 99 S, 333238

Abstract:

Intermodulation distortion (IMD) is known to be an impediment to progress in superconductor-based filter technology. The present invention's methodology for reducing IMD can open doors to heretofore unseen practical applications involving high temperature superconductor (HTS) filters. Typical inventive practice includes (a) increasing the thickness d, and/or (b) changing the operation temperature T, of the filter's HTS film. The film's thickness d is increased in such a way as to decrease the IMD power Pin accordance with the material-independent proportionate relationship∝1/. The film's operation temperature T is bettered or optimized in accordance with the material-independent proportionate relationship∝(λ())(())/(Δ()),and further in accordance with three individual material-dependent relationships, namely, between operation temperature T and each of linear penetration depth λ, gap maximum Δ, and kernel K. Some inventive embodiments include oxygen overdoping of the film as an additional/alternative IMD-reductive measure.

US Patent:

20120313452, Dec 13, 2012

Filed:

Nov 10, 2010

Appl. No.:

12/927318

Inventors:

Blaise L. Corbett - King George VA, US
Albert J. Corda - Dahlgren VA, US
Jack L. Price - Derwood MD, US
Yehoshua D. Agassi - Silver Spring MD, US
Walter D. Sessions - King George VA, US

Assignee:

United States Government, as represented by the Secretary of the Navy - Arlington VA

International Classification:

H03K 3/53

US Classification:

307106, 505150

Abstract:

A flux compression generator (FCG) is provided for producing an electromagnetic pulse (EMP). The FCG includes an environmental case, a reactive load, a dielectric core, a superconducting stator, an electric energy source, a load switch, and a transition device. The reactive load transmits the EMP in response to an electric current pulse. The dielectric core has proximal and distal ends within the case, with the stator disposed coaxially around the core that provides structural support. The case contains the electrical energy source, the stator, the core and the transition device. The energy source connects to the stator at the proximal end and powers the transition device. The load switch connects the reactive load to the stator at the distal end. The energy source initially provides an electric current to the stator. The device upon activation heats at least a portion of the stator to reversibly transition the portion from a superconducting state to a non-superconducting state. The stator transfers the electric current as the pulse to the reactive load upon the portion's transition to the non-superconducting state. The stator can be a superconducting helical coil that wraps around the core connected to a superconducting conductor disposed coaxially within the core. Alternatively, the stator can be a stack of superconducting rings disposed coaxially along the core. The superconducting coil and rings can preferably be composed of a high temperature superconductive material on a metal substrate.

US Patent:

6635368, Oct 21, 2003

Filed:

Dec 20, 2001

Appl. No.:

10/022340

Inventors:

Yehoshua Dan Agassi - Silver Spring MD

Assignee:

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

International Classification:

H01B 1200

US Classification:

428701, 505190, 505191, 505211, 505220, 505230, 505701

Abstract:

A film-based HTS device comprises a substrate and a superconducting film. A peripheral portion of the film is a-axis-aligned material which is so situated on the substrate as to describe a-b planar barriers which are perpendicular to the substrate and which in parallel fashion border upon the entire periphery of the film. The a-b planar barriers serve to block vortices which nucleate at the films periphery, thereby attenuating the overall vortex activity associated with the film, thereby attenuating the ELF and white noise which are normally prevalent in superconductor devices. Effectiveness in terms of arresting vortex motion may be increased by providing an interior film portion which is also a-axis-aligned material. It may be preferable to provide an interior film portion which is c-axis-aligned material, since this is easier to make and the a-axis-aligned peripheral portion of the film will be sufficiently effective in terms of âpinningâ the vortices.