John L Purcell

US Patent:

52377385, Aug 24, 1993

Filed:

Dec 10, 1991

Appl. No.:

7/805208

Inventors:

John R. Purcell - San Diego CA
Sibley C. Burnett - Cardiff by the Sea CA
Lewis R. Creedon - San Diego CA

Assignee:

Advanced Cryo Magnetics, Inc. - San Diego CA

International Classification:

H01L 3924

US Classification:

29599

Abstract:

A method of manufacturing a helium containment vessel for use with a pulsed superconducting magnetic separator system is described. The containment vessel includes a superconducting coil positioned within the cryogenic containment vessel for providing a magnetic field. The containment vessel includes a relatively thin metallic inner tube for holding liquid helium and the coil. The containment vessel also includes a relatively thick outer tube encompassing the inner tube with a relatively rigid insulative spacer positioned between the inner and outer tubes so that the tubes are not in contact with each other. The outer tube is predominantly metallic and has at least one joint formed of insulative material to prevent the outer tube from forming a low electrical resistance loop.

US Patent:

46251936, Nov 25, 1986

Filed:

Jun 4, 1984

Appl. No.:

6/616737

Inventors:

John R. Purcell - San Diego CA

Assignee:

GA Technologies Inc. - San Diego CA

International Classification:

H01F 722

US Classification:

335216

Abstract:

A lead assembly provides an electrical connection between a magnet coil maintained at low temperature in a boiling liquid bath within a closed container and a power supply terminal maintained at a higher temperature outside of the container. The assembly includes a length of cable which is superconducting at the low temperature and normally conducting at higher temperatures and is disposed within a tube which communicates with the interior of the container so as to vent vapor from the boiling liquid bath out of the container through the tube along the cable to cool the cable to superconducting temperature near the magnet coil. The cable is preferably formed of a plurality of loosely twisted copper-stabilized superconducting strands.

US Patent:

43696368, Jan 25, 1983

Filed:

Jul 6, 1981

Appl. No.:

6/280325

Inventors:

John R. Purcell - San Diego CA
Wilkie Y. Chen - San Diego CA
Walter E. Toffolo - Solana Beach CA

Assignee:

General Atomic Company - San Diego CA

International Classification:

F25B 1900

US Classification:

62514R

Abstract:

Methods and apparatus are provided for minimizing heat introduced by electrical leads into the cryogenic liquid in which a superconducting magnet is immersed. The electrical leads have normal portions extending from exterior of the cryogenic liquid containment vessel and thereinto and superconducting portions extending vertically downward therefrom and connected to the magnet. Means are provided to lower and raise the level of cryogenic liquid around the superconducting portions of the leads to fully immerse the supercoducting portions during periods of magnet energization and expose selected segments thereof when the magnet is de-energized. When exposed, the non-immersed segments provide a thermal resistance between the normal metal portions and the cryogenic liquid.

US Patent:

49303147, Jun 5, 1990

Filed:

Sep 8, 1989

Appl. No.:

7/404605

Inventors:

Sibley C. Burnett - Cardiff by the Sea CA
John R. Purcell - San Diego CA
William P. Creedon - San Diego CA
Chandrashekhar H. Joshi - Bedford MA

Assignee:

CDC Partners - San Diego CA

International Classification:

F02G 104

US Classification:

60517

Abstract:

Improved Stirling cycle machine including at least a pair of eccentric disks fixed to a pair of rotatable shafts in phase with each other and which eccentric disks upon rotation of the shafts (in opposite directions in the preferred embodiment) also rotate (in opposite directions in the preferred embodiment) and impart upward movement to a bellows defining a variable-volume compression or expansion chamber with a reduced tendency to also impart side thrust, rocking motion, or lateral movement to the bellows whereby bellows wear is reduced and the life of the bellows and the Stirling cycle machine is increased.

US Patent:

51481375, Sep 15, 1992

Filed:

Mar 15, 1991

Appl. No.:

7/669804

Inventors:

John R. Purcell - San Diego CA
Sibley C. Burnett - Cardiff by the Sea CA
Lewis R. Creedon - San Diego CA

Assignee:

Advanced Cryo Magnetics, Inc. - San Diego CA

International Classification:

H01F 700
H01F 100
F25B 1900

US Classification:

335301

Abstract:

A cryogenic containment vessel for use with a pulsed superconducting magnet system includes a superconducting coil positioned within the cryogenic containment vessel for providing a magnetic field. The containment vessel includes a relatively thin metallic inner tube for holding liquid helium and the coil. The containment vessel also includes a relatively thick outer tube encompassing the inner tube with a relatively rigid insulative spacer positioned between the inner and outer tubes so that the tubes are not in contact with each other. The outer tube is predominantly metallic and has at least one joint formed of insulative material to prevent the outer tube from forming a low electrical resistance loop. The inner tube provides a vacuum seal and the outer tube provides structural support for the inner tube so that eddy current losses resulting from ramping of the current to the coil are reduced. A method of fabricating the containment vessel is also disclosed.

US Patent:

RE363324, Oct 12, 1999

Filed:

Mar 2, 1998

Appl. No.:

9/033946

Inventors:

James G. Pierce - Westerville OH
Charles B. Hood - Naples FL
Sibley C. Burnett - San Diego CA
John R. Purcell - San Diego CA

Assignee:

PHPK Technologies, Inc. - Westerville OH

International Classification:

F17C 502

US Classification:

62 471

Abstract:

A refrigeration system includes a dewar and a refrigerator/liquefier which meets the variable demands of a superconducting magnet within the dewar. The system is sized to meet average loads over a defined duty cycle, and is variably operable to meed demands. In the preferred embodiment, a first supply of fluid circulates through a "condenser" element positioned in a dewar ullage to liquefy a separate supply of fluid in the dewar, and to refrigerate a pulsed cryogenic load therein, such as a superconducting magnet. A portion of the first supply of fluid may be diverted to refrigerate a second pulsed cryogenic load, such as magnet current leads permanently connected to the magnet. The dewar includes a cold gas vapor storage chamber separate from the dewar ullage, and the chamber is preferably located within the inner core of a solenoid superconducting magnet for compact and thermally efficient design. Responsive, independent adjustment of refrigeration to pulsed cryogenic loads is made possible.

US Patent:

49317598, Jun 5, 1990

Filed:

Apr 6, 1989

Appl. No.:

7/334291

Inventors:

Bruce C. Breneman - San Diego CA
John R. Purcell - San Diego CA
Raymond E. Sarwinski - San Diego CA

Assignee:

General Atomics

International Classification:

H01F 700

US Classification:

335301

Abstract:

A magnetic resonance imaging magnet has a solenoidal superconducting winding producing a magnetic field and defining an examination region within a bore thereof. The examination region receives a body to be examined. The solenoidal superconducting winding generates a quasi-static magnetic field for aligning atomic nuclei in the body being examined. A two-fold or minimally symmetric ferromagnetic shield has a pair of magnetic flux return paths positioned on opposite sides of the solenoidal superconducting winding for reducing the magnetic field intensity in a region proximate to and outside of the solenoidal superconducting winding. A magnetic field inhomogeneity compensating system reduces magnetic field inhomogeneities introduced into the magnetic field within the examination region by the minimally symmetric ferromagnetic shield to provide a highly uniform quasi-static magnetic field within the examination region.

US Patent:

50192477, May 28, 1991

Filed:

Nov 20, 1989

Appl. No.:

7/439422

Inventors:

John R. Purcell - San Diego CA
Sibley C. Burnett - Cardiff by the Sea CA
Lewis R. Creedon - San Diego CA

Assignee:

Advanced Cryo Magnetics, Inc. - San Diego CA

International Classification:

B03C 102
H02H 700

US Classification:

209224

Abstract:

A pulsed superconducting magnet system includes a vacuum vessel and a cryogenic containment vessel assembly disposed within the vacuum vessel. A superconducting coil is positioned within the cryogenic containment vessel assembly for providing a magnetic field. The vessel assembly includes a helium vessel including a relatively thin metallic inner tube for holding liquid helium and the coil. The helium vessel also includes a relatively thick outer tube encompassing the inner tube with a relatively rigid insulative spacer positioned between the inner and outer tubes so that the tubes are not in contact with each other. The outer tube is predominantly metallic and has at least one joint formed of insulative material to prevent the outer tube from forming a low electrical resistance loop. The inner tube provides a vacuum seal and the outer tube provides structural support for the inner tube so that eddy current losses resulting from ramping of the current to the coil are reduced. A method of fabricating the helium vessel is also disclosed.