# US 6,720,855 B2 · Magnetic-flux conduits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,855 B2 - Document ID: US6720855B2 - Status: Granted - Kind: B2 - Application number: 10/092,586 - Filed: 2002-03-08 - Published: 2003-09-11 - Granted: 2004-04-13 - Earliest claimed: 2002-03-08 - Assignees: University of North Carolina - Chapel Hill - Inventors: Leandra Vicci - Web page: https://patentgrep.com/patent/US6720855B2 ## CPC - H01F 6/06: Coils, e.g. winding, insulating, terminating or casing arrangements therefor - H01F 7/20: without armatures (cores H01F3/00; coils H01F5/00 {; shaping metal by applying magnetic forces B21D26/14; electromagnets specially adapted for NMR applications G01R33/381}) - H01F 27/363: {made of electrically conductive material} - H01F 30/08: without magnetic core - H01F 17/02: without magnetic core - H01F 27/34: Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields - H01F 27/36: Electric or magnetic shields or screens (movable for varying inductance H01F21/10) - H01F 30/16: Toroidal transformers - H01F 2006/001: {Constructive details of inductive current limiters} - Y10T 29/4902: Electromagnet, transformer or inductor - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A magnetic flux guiding apparatus comprises a conduit having a wall that comprises an electrically conducting material. An electrically insulating gap is formed in the wall along an entire length of the conduit. The electrically insulating gap prevents the conduit from having a closed electrical path that links any of the desired magnetic flux paths. For example, the electrically insulating gap can prevent the conduit from having a closed electrical path that surrounds a lengthwise axis of the conduit. The apparatus can also comprise a magnetic-field source that produces a magnetic flux that passes through an interior region bounded by the conduit. Where the conduit comprises a conventional electrically conducting material, the magnetic-field source can be a source of time-varying magnetic flux, such as an electrical coil. Where the conduit comprises an electrically superconducting material, the magnetic-field source can also be a source of time-varying magnetic flux or constant magnetic flux, such as a permanent magnet. ## Claims ### Claim 1 A method of making a magnetic-flux conduit, comprising: identifying one or more mathematical surfaces through which leakage of a desired magnetic flux is to be prevented; providing electrically conducting material that conforms to said one or more mathematical surfaces; and providing an electrically insulating gap in the electrically conducting material such that no closed electrical path of the electrically conducting material links a closed path of the desired magnetic flux, wherein an interior region of a magnetic-flux conduit thereby formed has a tapered shape between a first portion of the magnetic-flux conduit and a second portion of the magnetic-flux conduit. ### Claim 2 (depends on 1) The method of claim 1, wherein the interior region of the magnetic-flux conduit is hollow. ### Claim 3 (depends on 1) The method of claim 1, wherein the electrically conducting material is selected from the group consisting of copper, aluminum and silver. ### Claim 4 (depends on 1) The method of claim 1, further comprising providing at least one permeable magnetic core within an the interior region of the magnetic-flux conduit. ### Claim 5 (depends on 1) The method of claim 1, wherein the electrically conducting material comprises a superconducting material. ### Claim 6 (depends on 5) The method of claim 5, wherein the superconducting material is selected from the group consisting of yttrium-barium-copper-oxide materials and bismuth-strontium-calcium-copper-oxide materials. ### Claim 7 A method of providing a magnetic flux, comprising: providing a conduit having a wall that comprises an electrically conducting material, wherein an electrically insulating gap is formed in the wall along an entire length of the conduit, and wherein the electrically insulating gap prevents the conduit from having a closed electrical path that links any closed path of desired magnetic flux; providing a magnetic material within an interior region of the conduit; providing a magnetic-field source in proximity to the conduit; and operating the magnetic-field source to produce a magnetic flux that passes through the magnetic material and the interior region of the conduit such that a flux density of the magnetic flux exceeds a saturation magnetization of the magnetic material. ### Claim 8 (depends on 7) The method of claim 7, wherein the magnetic-field source is operated to produce a time-varying magnetic field. ### Claim 9 (depends on 7) The method of claim 7, wherein the magnetic-field source is an electrical coil. ### Claim 10 (depends on 7) The method of claim 7, wherein the electrically conducting material is selected from the group consisting of copper, aluminum and silver. ### Claim 11 (depends on 7) The method of claim 7, wherein the electrically conducting material comprises a superconducting material. ### Claim 12 (depends on 11) The method of claim 11, wherein the superconducting material is selected from the group consisting of yttrium-barium-copper-oxide materials and bismuth-strontium-calcium-copper-oxide materials. ### Claim 13 (depends on 7) The method of claim 7, wherein the interior region bounded by the conduit has a first interior cross-sectional area at a first portion the conduit, the interior region bounded by the conduit has a second interior cross-sectional area at a second portion of the conduit, the magnetic-field source is disposed in proximity to the first portion of the conduit, and the second interior cross-sectional area is smaller than the first interior cross-sectional area. ### Claim 14 (depends on 13) The method of claim 13, wherein the interior region bounded by the conduit has a tapered shape between the first portion of the conduit and the second portion of the conduit. ### Claim 15 A method of providing a magnetic flux, comprising: providing a conduit having a wall that comprises an electrically conducting material, wherein an electrically insulating gap is formed in the wall along an entire length of the conduit, and wherein the electrically insulating gap prevents the conduit from having a closed electrical path that surrounds a lengthwise axis of the of the conduit; providing a magnetic material within an interior region of the conduit; providing a magnetic-field source in proximity to the conduit; and operating the magnetic-field source to produce a magnetic flux that passes through the magnetic material and through the interior region of the conduit such that a flux density of the magnetic flux exceeds a saturation magnetization of the magnetic material. ### Claim 16 (depends on 15) The method of claim 15, wherein the magnetic-field source is operated to produce a time-varying magnetic field. ### Claim 17 (depends on 15) The method of claim 15, wherein the magnetic-field source is an electrical coil. ### Claim 18 (depends on 15) The method of claim 15, wherein the electrically conducting material is selected from the group consisting of copper, aluminum and silver. ### Claim 19 (depends on 15) The method of claim 15, wherein the electrically conducting material comprises a superconducting material. ### Claim 20 (depends on 19) The method of claim 19, wherein the superconducting material is selected from the group consisting of yttrium-barium-copper-oxide materials and bismuth-strontium-calcium-copper-oxide materials. ### Claim 21 (depends on 15) The method of claim 15, wherein the interior region of the conduit has a first interior cross-sectional area at a first portion the conduit, the interior region of the conduit has a second interior cross-sectional area at a second portion of the conduit, the magnetic-field source is disposed in proximity to the first portion of the conduit, and the second interior cross-sectional area is smaller than the first interior cross-sectional area. ### Claim 22 (depends on 21) The method of claim 21, wherein the interior region bounded by the conduit has a tapered shape between the first portion of the conduit and the second portion of the conduit. ### Claim 23 A method of providing a magnetic flux, comprising: providing a conduit having a wall that comprises an electrically conducting material, wherein an electrically insulating gap is formed in the wall along an entire length of the conduit, wherein the electrically insulating gap prevents the conduit from having a closed electrical path that surrounds a lengthwise axis of the of the conduit, and wherein magnetic material is excluded from an interior region of the conduit; providing an electrical coil that surrounds a portion of the conduit; and applying electrical energy to the coil to produce a magnetic flux that passes through the interior region of the conduit. ### Claim 24 (depends on 23) The method of claim 23, wherein the electrically conducting material is selected from the group consisting of copper, aluminum and silver. ### Claim 25 (depends on 23) The method of claim 23, wherein the electrically conducting material comprises a superconducting material. ### Claim 26 (depends on 25) The method of claim 25, wherein the superconducting material is selected from the group consisting of yttrium-barium-copper-oxide materials and bismuth-strontium-calcium-copper-oxide materials. ### Claim 27 (depends on 23) The method of claim 23, wherein the interior region bounded by the conduit has a first interior cross-sectional area at a first portion the conduit, the interior region of the conduit has a second interior cross-sectional area at a second portion of the conduit, the coil is disposed in proximity to the first portion of the conduit, and the second interior cross-sectional area is smaller than the first interior cross-sectional area. ### Claim 28 (depends on 27) The method of claim 27, wherein the interior region of the conduit has a tapered shape between the first portion of the conduit and the second portion of the conduit.