Patent Number: 045308128
Section: claims

1. A composite magnetic coil winding comprising at least two conductor segments, a first segment of said at least two conductor segments being made from a copper material and a second segment of said at least two conductor segments being made from an aluminum material, each of said conductor segments defining a circumferential portion of said coil winding and each of said segments being joined to an adjacent segment to form said coil winding. 2. The composite magnetic coil winding of claim 1, wherein said circumferential portions are joined at a high strength joint. 3. The composite magnetic coil winding of claim 2, wherein the joint has low electrical resistance. 4. The composite magnetic coil winding of claim 2 or 3, wherein said winding has a generally regular and continuous surface and said joint does not protrude from said surface. 5. The composite magnetic coil winding of claim 2 or 3, wherein said coil winding has means for removing heat from said coil winding and wherein said joint does not interfere with said heat removal means. 6. The composite magnetic coil winding of claim 2 or 3, wherein said joint is a mechanical joint. 7. The composite magnetic coil winding of claim 2 or 3, wherein said joint is a metallurgical joint. 8. The composite magnetic coil winding of claim 1, wherein the copper material is in the form of a copper alloy. 9. The composite magnetic coil winding of claim 1, wherein the aluminum material is in the form of an aluminum alloy. 10. The composite magnetic coil winding of claim 8, wherein the copper alloy is copper beryllium. 11. The composite magnetic coil winding of claim 8, wherein the copper alloy is copper berylliumnickel. 12. The composite magnetic coil winding of claim 8, wherein the copper alloy is a Mg-Zr-Cr copper alloy. 13. The composite magnetic coil winding of claim 9, wherein the aluminum alloy is from the 2000 series of aluminum alloys. 14. The composite magnetic coil winding of claim 9, wherein the aluminum alloy is from the 6000 series of aluminum alloys. 15. The composite magnetic coil winding of claim 9, wherein the aluminum alloy is from the 7000 series of aluminum alloys. 16. The composite magnetic coil winding of claim 9, wherein the aluminum alloy is reinforced with graphite. 17. A composite magnetic coil winding for a tokamak reactor comprising at least two conductor segments, a first segment of said at least two segments defining a first circumferential portion of said coil winding and comprising a copper material and a second segment of said at least two segments defining a second circumferential portion of said coil winding and comprising an aluminum material and wherein said segments are joined at a high strength, low electrical resistance joint. 18. The composite magnetic coil winding of claim 17, wherein said coil winding has a generally smooth and continuous surface and wherein said joint does not protrude from said surface. 19. The composite magnetic coil winding of claim 17, wherein said coil winding has means for removing heat from said coil winding and wherein said joint does not interfere with said heat removal means. 20. The composite magnetic coil winding of claim 17, wherein said joint is a mechanical joint. 21. The composite magnetic coil winding of claim 17, wherein said joint is a metallurgical joint. 22. The composite magnetic coil winding of claim 17, wherein said copper material is a copper alloy. 23. The composite magnetic coil winding of claim 17, wherein the Al material is an Al alloy. 24. A toroidal reactor for producing fusion reactions, said reactor having a toroidal field generating means which are exposed to a neutron flux produced by said fusion reactions, said toroidal field means comprising at least one composite magnetic coil winding having at least two circumferential segments, a first of said at least two circumferential segments comprising a copper material and a second of said at least two circumferential segments comprising an aluminum material and wherein each of said circumferential segments are joined at a high strength, low electrical resistance joint to form said coil winding. 25. The toroidal reactor of claim 24, wherein said coil winding has a generally smooth and continuous surface and wherein said joint does not protrude from said surface. 26. The toroidal reactor of claim 24, wherein said toroidal field coil means further comprises heat removal means and wherein said joint does not interfere with said heat removal means. 27. The toroidal reactor of claim 24, wherein said joint is a mechanical joint. 28. The toroidal reactor of claim 24, wherein said joint is a metallurgical joint. 29. The toroidal reactor of claim 24, wherein said reactor has a main axis and wherein said copper field generating means nearest said main axis and said aluminum material segment is positioned on an opposite side of said toroidal field generating means, furthest from said main axis. 30. The toroidal reactor of claim 24, wherein said copper material is a copper alloy. 31. The toroidal reactor of claim 24, wherein the aluminum material is an aluminum alloy. 32. The toroidal reactor of claim 30, wherein the copper alloy is from the group consisting of copper beryllium and Mg-Zr-Cr-copper. 33. The toroidal reactor of claim 31, wherein the aluminum alloy is from the group consisting of the 2000, 6000 and 7000 series of aluminum alloys. 34. The toroidal reactor of claim 31, wherein aluminum alloy is reinforced with graphite. 35. A method of forming a composite field coil winding for a fusion reactor comprising: providing a first circumferential coil segment made of a copper material;  providing a second circumferential coil segment made of an aluminum material;  joining said first and second circumferential coil segments at a relatively high strength, low electrical resistance joint to form a toroidal field coil winding.  providing a first circumferential coil segment made of a first electrically conductive material operable to conduct a first current density and having a first strength operable to support a first load;  providing a second circumferential coil segment made of a second electrically conductive material operable to support a second current density lower than said first current density and having a second strength operable to support a load lower than said first load and having a relatively low neutron absorption cross section whereby neutrons can pass through said second circumferential coil segment more freely than through first circumferential coil segment; and  joining said first and second circumferential coil segments at an electrically conductive joint having a strength at least equal to said second strength to form a toroidal field coil winding. 36. A method of forming a composite field coil winding for a fusion reactor comprising: 37. The method of claim 36 or 35 further including the step of positioning the first coil segment at a location of maximum stress and current density. 38. The method of claim 37 further including the step of positioning the second coil segment at a location of maximum neutron fluence to minimize neutron capture. 39. The method of claim 36 including the step of making the first coil segment from a copper material. 40. The method of claim 36 including the step of making the second coil segment from an aluminum material. 41. The method of claim 39 or 35, wherein the copper material is a copper alloy. 42. The method of claim 40 or 35, wherein the aluminum material is an aluminum alloy.