Michael J Hennessy

US Patent:

6836112, Dec 28, 2004

Filed:

Apr 16, 2003

Appl. No.:

10/414997

Inventors:

Michael J. Hennessy - Ballston Lake NY 12019

International Classification:

G01V 300

US Classification:

324300

Abstract:

Magnetic resonance force microscopy (MRFM) is a technology capable of detecting the magnetic resonance of a small number of spins and, potentially, a single spin of an electron or nucleus. Most methods use soft cantilevers with microscopic dimensions (microns) which have been developed for atomic force microscopy. Cantilevers have been both a solution and problem of high sensitivity force detection. They are difficult to fabricate and it is difficult to achieve the right sensitivity and stiffness with them. The proposed invention eliminates the cantilever and replaces it with small, magnetically sensitive objects called birdies, which are manipulated above a sample using electromagnetic field control. The basic principles of the cantilever-free MRFM are the same as those of traditional, cantilever-based systems. Motion of the birdie induced by magnetic resonance is monitored using optical interferometry.

US Patent:

7091799, Aug 15, 2006

Filed:

Dec 22, 2003

Appl. No.:

10/744402

Inventors:

Michael J. Hennessy - Ballston Lake NY, US
Eduard K. Mueller - Ballston Lake NY, US

International Classification:

H04B 3/28
H01B 12/00
H02J 1/02

US Classification:

333 12, 333 99 S, 363 39

Abstract:

Losses are reduced in electrical conductors and filters, especially those made with superconducting cables or inductors, which carry currents having both direct current (DC) and alternating current (AC) portions as in rectifier busses and power distribution systems. Superconducting cables and chokes are capable of passing direct current with practically zero losses, but they exhibit considerable AC losses. A low impedance AC bypass of the superconducting cables and chokes minimizes these losses.

US Patent:

7126810, Oct 24, 2006

Filed:

Jun 24, 2004

Appl. No.:

10/875458

Inventors:

Otward M. Mueller - Ballston Lake NY, US
Eduard K. Mueller - Ballston Lake NY, US
Michael J. Hennessy - Ballston Lake NY, US

International Classification:

H01G 4/38

US Classification:

361328, 3613014, 3613214, 3613081, 361227, 361311

Abstract:

This invention describes a means by which performance characteristics of capacitors can be improved. This is achieved by reducing the temperature, preferably but not exclusively to cryogenic temperatures below 100 K. This is based on the observation that the dielectric strength, dielectric losses and plate losses in many capacitors, such as film capacitors, improve as the temperature is decreased. A cryogenic capacitor bank is also described, which exhibits energy densities up to four times those of conventional, room-temperature capacitor banks. Cryogenic capacitors can be combined with cryogenically operated semiconductors or with superconductors in such a way as to reduce the size, weight, and losses of a complete system.

US Patent:

7193336, Mar 20, 2007

Filed:

Oct 23, 2003

Appl. No.:

10/691767

Inventors:

Otward M. Mueller - Ballston Lake NY, US
Michael J. Hennessy - Ballston Lake NY, US

International Classification:

H01H 67/00

US Classification:

307113, 307147, 361 19, 505163

Abstract:

A method and apparatus for reducing conductive thermal losses in high-current cryogenic power electronics systems needing large cables to interface between warm and cold environments. Thermal losses increase with increasing cross-sectional area. The total current at the warm/cold interface is split into many smaller currents by splitting the power buss into a plurality of parallel leads. Respective physical switches in each smaller lead at the interface interrupt current flow, and at the same time open the path for thermal conduction along the lead. When little or no current is flowing through the system, selected smaller leads of the power buss are physically opened by the associated switches to stop the thermal and electrical flow along these leads. Current diverts to another parallel lead in the buss but the cross section for heat flow is reduced at the interface.

US Patent:

7352233, Apr 1, 2008

Filed:

Jun 13, 2005

Appl. No.:

11/151508

Inventors:

Otward Mueller - Ballston Lake NY, US
Eduard K. Mueller - Ballston Lake NY, US
Michael J. Hennessy - Ballston Lake NY, US

International Classification:

H03K 17/72

US Classification:

327438, 327440

Abstract:

The highest-power switches now available are based on thyristor-type devices: GTOs (Gate turn-off thyristors), MTOs (MOS controlled turn-off thyristors), IGCTs (Integrated gate commutated thyristors), and the new ETOs (Emitter turn-off thyristors). These devices handle kilovolts and kiloamperes for megawatt inverters/converters. Measurements by the inventors show that conduction losses of MOSFETs and switching losses of IGCTs are drastically decreased by cryo-cooling. IGCTs, ETOs, and MTOs, together with many small, low voltage MOSFETs for gate and emitter turn-off circuitry, are cryo-cooled to attain much higher switching speeds and a reduction in size, weight and cost of high-power (megawatt range) equipment.

US Patent:

7369377, May 6, 2008

Filed:

Sep 12, 2005

Appl. No.:

11/224184

Inventors:

Michael J. Hennessy - Ballston Lake NY, US
John N. Park - Rexford NY, US
Otward M. Mueller - Ballston Lake NY, US
Eduard K. Mueller - Ballston Lake NY, US

International Classification:

H02H 7/00
H02H 9/00
H01L 29/00
H01L 23/34

US Classification:

361 19, 257532, 257536, 257713, 257714, 257716

Abstract:

Switching losses and conduction losses are isolated by networks which are partially cryogenic and partially at room temperature. Switching losses are independent of temperature. Advantageously the switching losses are taken in a snubber network at room temperature and conduction losses are incurred at cryogenic temperatures, where majority carrier devices like MOSFETs operate with ultra low on-state resistance and corresponding low conduction losses. Low loss leads carry current efficiently from the cryogenic environment to room temperature without adversely affecting refrigeration. Switch and snubber network may both operate cryogenically.

US Patent:

7371968, May 13, 2008

Filed:

Jun 1, 2004

Appl. No.:

10/858459

Inventors:

Michael J. Hennessy - Ballston Lake NY, US

International Classification:

H01B 12/00

US Classification:

1741251, 174 154, 29599

Abstract:

A detachable superconducting lead includes a vacuum-sealed thermal transition through which a stabilized conductor passes. Two identical leads are attached and surrounded by a sealed Dewar and allowed to cool either naturally or by way of a cooling element. Detaching the leads requires the joint to be heated up by a heat transfer unit or by a heat gun after the Dewar is removed. Once warmed, the lead can be disassembled with tooling appropriate to the joint. In many instances, regular fasteners can be used. Removable Dewars may be constructed with insulation (including vacuum) using O-rings and flanges.

US Patent:

7391133, Jun 24, 2008

Filed:

Sep 25, 2003

Appl. No.:

10/670810

Inventors:

Michael J. Hennessy - Ballston Lake NY, US
Eduard K. Mueller - Ballston Lake NY, US

International Classification:

H01H 33/59

US Classification:

307113, 307115, 307125, 307131, 3071414, 307143, 361 2, 361 8, 361 13

Abstract:

An electrical switching topology for a hybrid switch provides extremely low losses in both cryogenic and non-cryogenic electronic systems. In this switch having switch modules connected in parallel, switching losses in a first module are separated from conduction losses in the parallel-connected second module. The conduction losses are then further reduced by cryogenically cooling the second module. Since the switching losses of the first module can be absorbed outside a cryogenic container, the switching losses do not add to the cryogenic heat load. In other applications, the switching module operates at lower temperatures to provide higher switching speeds and reduces switching heat generation.