Patent Publication Number: US-8543178-B2

Title: Superconductor induction coil

Description:
The present invention claims priority on U.S. Provisional Application Ser. No. 60/984,935 filed Nov. 2, 2007 entitled “HTS Superconductor Wire for Making an Inductor Coil”, which is incorporated herein by reference. 
     The present invention is directed to an apparatus and a method for heating a workpiece with the use of a superconducting material, particularly to an apparatus and method of induction heating and/or melting a workpiece by an induction coil that is at least partially formed from a superconductor material, and more particularly to an apparatus and method of induction heating and/or melting a metallic or non-metallic workpiece by an induction coil that is at least partially formed from an HTS superconductor material. 
    
    
     BACKGROUND OF THE INVENTION 
     Induction heating apparatuses used to heat or melt metals operate on the principle of inducing eddy currents in the metal workpiece to be heated. The eddy currents are induced in the metal workpiece by passing an alternating current through an induction coil to generate a time-varying magnetic field, or induction field. Depending upon the magnitude and frequency of the alternating current in the induction coil, the induction field can be used for melting and/or heating the metal workpiece. 
     The efficiency of an induction coil to melt or heat a metal workpiece depends, in part, on the amount of energy (in the form of electromagnetic energy) which couples from the induction coil to the metal workpiece and is converted into heat energy in the metal workpiece. Present materials that are used to manufacture induction coils have the disadvantage of resistive losses within the conventional materials (i.e., copper) used to form the induction coil. In particular, anon-ferrous load of induction coils have efficiencies as low as 40% due to the current to heat them inductively is very large. The resistive losses are based on the square of the current, thus become significant when large currents are used to inductively heat a metal workpiece. 
     In an effort to reduce the resistive losses, some induction coils have been manufactured using superconducting materials. However, it has been found that superconductors produce losses when exposed to an alternating magnetic field. As such, the heat from the AC losses in the superconductors must be cooled at very low temperatures, which cooling can be very expensive. Superconductors have been used for some time in the medical industry for Magnetic Resonance Imaging. Superconductors have also been used in the motor industry for winding armatures to make large motors much smaller. In the area of Magnetic Hydrodynamic Drives, superconductors have been used in large ships. Transmission lines made from superconductors are used to carry large amounts of current and are in place around the United States. 
     One possible advance with regard to superconductors is the formation of a static or DC magnetic field that has little or no energy losses. Superconductors can, under DC conditions, conduct electric current with very little energy losses. Several types of induction coils that include superconductor materials are disclosed in U.S. Pat. Nos. 5,781,581 and 6,730,890, United States Publication No. 2006/0157476, Chinese publication No. CN 101017729, Norwegian Patent No. 308,980, and PCT Publication No. WO 03/044813, all of which are incorporated entirely herein. 
     Although these early uses of superconductor materials in induction coils had great potential, these superconducting materials were very expensive to use, the cooling systems requiring use of the superconducting materials was also very expensive and complicated to use, and the configuration of the induction coil that included the superconducting material was difficult to manufacture due to the configuration requirement of the superconducting material. 
     In view of the current state of induction coils, there remains a need for an induction coil that includes a superconducting material, and which induction coil is easier to manufacture and simpler and less costly to operate. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and a method for heating a workpiece with the use of a superconducting material, and more particularly to an apparatus and method of induction heating and or melting a metallic or non-metallic workpiece by an induction coil that is at least partially formed from a High Temperature Superconductor (HTS) material. In one non-limiting embodiment of the invention, there is provided an improved method and apparatus for heating and melting materials using an induced magnetic field with an HTS material that fully forms or is included in an induction coil. The HTS material can be formed into an HTS wire that is manufactured for the purpose of carrying electrical current. The HTS wires can be included in an induction coil, which are normally copper conductors. The shape of the induction coil is often a helical wound coil of induction wire or tube; however, it can be appreciated that the induction coil that includes the HTS wire can be formed in any shape whose purpose is to induce current into a workpiece that acts as a current-carrying load of the induction coil. In another and/or alternative non-limiting embodiment of the invention, the induction coil that includes the HTS wire can be designed to operate at higher frequencies than line frequency (60 Hz). In prior art induction coils that included a superconducting material, the current frequency that was supplied to the induction coil did not exceed 60 Hz. The induction coil of the present invention is designed to operate at current frequencies of 60 Hz or lower or at frequencies that exceed 60 Hz (e.g., 100 Hz, 200 Hz, 300 Hz, 400 Hz, 500 Hz, 600 Hz, 5 kHz, 10 kHz, 100 kHz, 1000 kHz, 10000 kHz, etc.). It is believed that the induction coil that includes the HTS wire of the present invention can increase efficiencies of induction coil at all frequencies. In one non-limiting aspect of the present invention, the induction coil that includes HTS wire of the present invention can be used at frequencies of 75-200 Hz, and more particularly at about 100 Hz. During conventional induction heating and/or melting of a workpiece, the induction coil converts electricity into thermal energy in the workpiece using alternating magnetic fields. The induction coil efficiency can be up to about 96% for magnetic ferrous workpieces. For non-ferrous metal and other non-magnetic conductive materials, the efficiency of heating by the induction coil can drop to as low as about 40% due to I 2 R losses in the induction coil. The High Temperature Superconductor (HTS) induction coils that include HTS wire of the present invention can achieve nearly zero resistance at low temperatures. As such, the I 2 R losses of the HTS induction coil of the present invention can be nearly zero, thereby increasing the efficiency for the non-ferrous metal and nonmagnetic conductive materials to approach 100% (e.g., at least 80%, at least 90%, etc.). The current density of the HTS induction coil of the present invention wire is believed to be much higher than classic induction coil conductors, such as an induction coil formed of copper. With high current densities, the HTS induction coil of the present invention is believed to form an induction magnetic field strength that is as strong or stronger than classic induction coil conductors. Such stronger induction magnetic field strength is believed to improve the efficiency and effectiveness of induction heating and melting applications. As defined herein, low temperature is defined as a temperature at or above 77° K (−196° C.) and at or below ambient temperature 295° K (22° C.). As such a superconducting material that is not superconductive at a temperature (i.e., critical temperature) at or above 77° K is not an HTS material as defined in this invention. 
     In one non-limiting aspect of the present invention, the induction coil of the present invention includes a plurality of HTS wires that are positioned in parallel with one another to accommodate the current requirements of various induction applications. As can be appreciated, any induction coil of any shape can potentially be formed in accordance with the present invention. Non-limiting induction coils that can be used, include, but are not limited to, wide rectangular coils, channel heating and channel melting coils, coreless melting coils, billet heating coils, bar heating coils, etc. 
     In another and/or alterative non-limiting aspect of the present invention, the use of one or more HTS wires that can be used as or included in an induction coil and cooled by liquid having a boiling point or sublimation point that is no more than 295° K (22° C.) at 1 atm. In one non-limiting embodiment of the invention, the cooling liquid is or includes liquid nitrogen. Liquid nitrogen, when used, has the benefit of being a common cryogenic fluid. Liquid hydrogen has been used in the past in superconductor applications; however, due to the very low boiling point of liquid hydrogen, liquid hydrogen is expensive to use and very costly to maintain in liquid form. The use of hydrogen gas can also be dangerous, thus is not used in most commercial applications. In another and/or alternative non-limiting embodiment of the invention, the cooling liquid can be contained in a chamber that partially or fully surrounds the HTS wire. In one non-limiting aspect of this embodiment, the chamber, when used, can be insulated to keep the cooling liquid cold. 
     In still another and/or alterative non-limiting aspect of the present invention, an electric current is flowed through one or more induction coils that are formed of or include one or more HTS wires. The current flowing through the one or more induction coils is used to heat and/or melt a workpiece when the workpiece is moved in the magnetic field formed by the one or more induction coils. In one embodiment of the invention, the material to be heated and/or melted is moved generally orthogonal to the static magnetic field, thus forming an electric field that is perpendicular to the direction of movement of the workpiece and the magnetic field. The electric field that is formed induces currents in the workpiece that cause resistive losses that result in the heating of the workpiece. Additionally, currents can be induced in an electrically conducting workpiece when it is moved in the direction of the static field and the intensity of the magnetic field is varied in the same direction. In another embodiment of the invention, the material to be heated and/or melted is moved through a non-static or alternating magnetic field. 
     In yet another and/or alterative non-limiting aspect of the present invention, the HTS material that is used in the HTS wire of the present invention is superconductive at temperatures (i.e., critical temperature) of at least about 76° K (−197° C.). The HTS wire of the present invention can be formed of one or more superconductive materials. When more than one HTS wire is used in an inductor coil, the materials used in the one or more HTS wires can be the same or different. Non-limiting examples of superconductive materials and their maximum temperature that such material maintain superconductive properties that can fully or partially be used to form the HTS wire that is used in the present invention include, but are not limited to, Sn 1.4 In 0.6 Ba 4 Tm 5 Cu 7 O 20+  (175° K); SnInBa 4 Tm 4 Cu 6 O 18+ (150° K); Sn 4 Ba 4 (Tm 2 Ca)Cu 7 O x (127° K); (Hg 0.8 Tl 0.2 )Ba 2 Ca 2 Cu 3 O 8.33 (138° K); HgBa 2 Ca 2 Cu 3 O 8  (135° K); HgBa 2 Ca 3 Cu 4 O 10+  (126° K); HgBa 2 (Ca 1-x Sr x )Cu 2 O 6+  (125° K); HgBa 2 CuO 4 + (98° K); Tl 2 Ba 2 Ca 2 Cu 3 O 10  (128° K); (Tl 1.6 Hg 0.4 )Ba 2 Ca 2 Cu 3 O 10+  (126° K); TlBa 2 Ca 2 Cu 3 O 9+  (123° K); (Tl 0.5 Pb 0.5 )Sr 2 Ca 2 Cu 3 O 9  (120° K); Tl 2 Ba 2 CaCu 2 O 6  (118° K); TlSnBa 4 TmCaCu 4 O x  (115° K); TIBa 2 Ca 3 Cu 4 O 11  (112° K); TlBa 2 CaCu 2 O 7+  (103° K) Tl 2 Ba 2 CuO 6  (95°K); TlSnBa 4 Y 2 Cu 4 O x (86° K); Sn 2 Ba 2 (Tm 0.5 Ca 0.5 )Cu 3 O 8+ (115° K); SnInBa 4 Tm 3 Cu 5 O x (113° K); Sn 3 Ba 4 Tm 3 Cu 6 O x (109° K); Sn 3 Ba 8 Ca 4 Cu 11 O x (109° K); SnBa 4 Y 2 Cu 5 O x (107° K); Sn 4 Ba 4 Tm 2 YCu 7 O x  (104° K); Sn 4 Ba 4 CaTmCu 4 O x (100° K); Sn 4 Ba 4 Tm 3 Cu 7 O x (98° K); Sn 2 Ba 2 (Y 0.5 Tm 0.5 )Cu 3 O 8+ (96° K); Sn 3 Ba 4 Y 2 Cu 5 O x (91° K); SnInBa 4 Tm 4 Cu 6 O x (87° K); Sn 2 Ba 2 (Sr 0.5 Y 0.5 )Cu 3 O 8 (86° K); Sn 4 Ba 4 Y 3 Cu 7 O x  (80° K); Bi 1.6 Pb 0.6 Sr 2 Ca 2 Sb 0.1 Cu 3 O y (115° K); Bi 2 Sr 2 Ca 2 Cu 3 O 10  (110° K); Bi 2 Sr 2 CaCu 2 O 9 (110° K); Bi 2 Sr 2 (Ca 0.8 Y 0.2 )Cu 2 O 8  (96° K); Bi 2 Sr 2 CaCu 2 O 8 (92° K); (Ca 1-x Sr x )CuO 2  (110° K); YSrCa 2 Cu 4 O 8+  (101° K); (Ba,Sr)CuO 2 (90° K); BaSr 2 CaCu 4 O 8+ (90° K); Pb 3 Sr 4 Ca 3 Cu 6 O x (106° K); Pb 3 Sr 4 Ca 2 Cu 5 O 15+  (101° K): (Pbl 1.5 Sn 1.5 )Sr 4 Ca 2 Cu 5 O 15+ (95° K); AuBa 2 Ca 3 Cu 4 O 11 (99° K); AuBa 2 (Y, Ca)Cu 2 O 7 (82° K); (Y 0.5 Lu 0.5 )Ba 2 Cu 3 O 7  (107° K); (Y 0.5 Tm 0.5 )Ba 2 Cu 3 O 7  (105° K); (Y 0.5 Gd 0.5 )Ba 2 Cu 3 O 7  (97° K); Y 2 CaBa 4 Cu 7 O 16  (97° K); Y 3 Ba 4 Cu 7 O 16  (96° K); NdBa 2 Cu 3 O 7  (96° K); Y 2 Ba 4 Cu 7 O 15  (95° K); GdBa 2 Cu 3 O 7  (94° K); YBa 2 Cu 3 O 7  (92° K); TmBa 2 Cu 3 O 7  (90° K); YbBa 2 Cu 3 O 7  (89° K); GaSr 2 (Ca 0.5 Tm 0.5 )Cu 2 O 7  (99° K); Ga 2 Sr 4 Y 2 CaCu 5 O x  (85° K); Ga 2 Sr 4 Tm 2 CaCu 5 O x  (81° K); and/or La 2 Ba 2 CaCu 5 O 9+ (79° K). The temperature next to each of the materials listed above is the believed critical temperature of superconductivity for such material. As can be appreciated, other or additional superconductive materials can be used to fully or partially form the HTS wire. As can also be appreciated, more than one superconductive material can be used to fully or partially form the HTS wire. 
     In still yet another and/or alternative non-limiting aspect of the present invention, the HTS wire of the present invention that is used in an induction coil is formed of a plurality of layers of material. In one non-limiting embodiment of the invention, there is provided a base metal layer that forms the backbone of the HTS wire. This base metal layer is generally not a superconductive material. In one non-limiting aspect of this embodiment, the base metal layer is formed of non-magnetic metals or non-magnetic metal alloys. In another non-limiting aspect of this embodiment, the base metal layer includes or is fully formed of a metal alloy that includes one or more of the following metals, namely aluminum, copper, lead, magnesium, nickel, platinum, nickel, silver, and tungsten. In still another non-limiting aspect of this embodiment, the base metal layer is formed of an alloy that includes nickel and tungsten. In yet another non-limiting aspect of this embodiment, the base metal layer is formed of an alloy that includes at least about 90 weight percent nickel and tungsten. In still yet another non-limiting aspect of this embodiment, the base metal layer is formed of an alloy that includes at least about 95 weight percent nickel and tungsten. The base metal layer is generally the thickest layer of the HTS wire; however, this is not required. The base metal layer can be formed of one or more layers of metal. When two or more metal layers are used to form the base metal layer, the composition of the different metal layers can be the same or different. In another and/or alternative embodiment of the present invention, the HTS wire can include one or more layers of buffer materials between the base metal layer and the superconductive material in the HTS wire; however, this is not required. These one of more buffer layers, when used, are typically a ceramic material formed of one or more oxides of rare earth metals; however, this is not required. Non-limiting examples of materials that can be used to form one or more of the buffer layers include, but are not limited to, cerium oxide, yttrium oxide and yttrium-stabilized zirconium ceramic. In one non-limiting aspect of this embodiment, a plurality of buffer layers are included on the HTS wire. In still another and/or alternative embodiment of the present invention, the HTS wire includes one or more layers of superconductive material positioned at least partially on the base metal layer and or one or more buffer layers, when used. In yet another and or alternative embodiment of the present invention, the HTS wire includes a top metal layer on top of the one or more layers of superconductive material. In one non-limiting aspect of the embodiment, the base metal layer and top metal layer are designed to provide protection to the top, sides and base of the HTS wire. In another and/or alternative non-limiting aspect of this embodiment, the top metal layer includes one or more noble metals (e.g., gold, palladium, platinum, rhodium, silver, tantalum, etc.). In one non-limiting aspect of this embodiment, the noble metal includes silver. In another non-limiting aspect of this embodiment, the noble metal includes at least about 50 weight percent silver. In still another non-limiting aspect of this embodiment, the noble metal includes at least about 80 weight percent silver. In yet another non-limiting aspect of this embodiment, the noble metal includes at least about 90 weight percent silver. The top metal layer can be formed of one or more layers of metal. When two or more metal layers are used to form the top metal layer, the composition of the different metal layers can be the same or different. 
     In another and/or alternative non-limiting aspect of the present invention, there is provided one or more power cable arrangements that connect a power supply to one or more induction coils, wherein the power cable includes one or more HTS wires of the present invention. In one non-limiting arrangement, the power cable connects to one or more induction coils, wherein the induction coil includes one or more HTS wires of the present invention. In one non-limiting embodiment of the invention, one or more layers of HTS wires in the power cable can be wound about a core; however, this is not required. The core, when used can be a metal core; however, this is not required. The core, when used, is generally formed of an electrically conductive material; however, this is not required. The core, when used, is generally formed of a non-magnetic material; however, this is not required. Non-limiting materials that can be used to at least partially form the core, when used, include, but are not limited to, aluminum, copper, lead, magnesium, platinum, silver and tungsten. As can be appreciated, the core, when used, can be formed of more than one material; however, this is not required. In another and/or alternative non-limiting embodiment of the invention, the power cable can include a high voltage dielectric material that is positioned about the one or more HTS wires; however, this is not required. The high voltage dielectric material is used to at least partially electrically insulate the one or more HTS wires from the outer layers of the power cable. Various types of dielectric materials can be used (e.g., ceramic materials, plastics, fiber reinforced materials, etc.). In one non-limiting embodiment, the dielectric material can include, but is not limited to, FRP (Fiberglass Reinforced Plastic), PVC (Poly Vinyl Chloride), etc. In one non-limiting design, the dielectric material is a FRP sold commercially as G-10. In another and/or alternative non-limiting embodiment of the invention, the power cable can include an HTS shield tape that is wrapped directly around the one or more HTS wires or around the high voltage dielectric material, when used. In still another and/or alternative non-limiting embodiment of the invention, the power cable can include a shielding layer that is wrapped directly around the HTS shield tape, when used, or around the high voltage dielectric material, when used. The shielding layer, when used, is generally formed of a non-magnetic material; however, this is not required. Non-limiting materials that can be used to at least partially form the shielding layer, when used, include, but are not limited to, aluminum, copper, lead, magnesium, platinum, silver and tungsten. As can be appreciated, the shielding layer, when used, can be formed of one or more layers. As can also be appreciated, the shielding can be formed of one or more materials. In yet another and/or alternative non-limiting embodiment of the invention, the power cable includes an inner cryostat wall. The inner cryostat wall is positioned about and at least partially spaced from the one or more HTS wires, or the high voltage dielectric material, when used, or the HTS shield tape, when used, or the shielding layer, when used, so as to form a passageway for a cooling fluid (e.g., liquid nitrogen, etc.) to at least partially flow about and cool the core, when used, the one or more HTS wires, or the high voltage dielectric material, when used, or the HTS shield tape, when used, or the shielding layer, when used. The inner cryostat wall can be formed of any type of durable material that can withstand contact with the cooling fluid. Typically the inner cryostat wall is a non-conducting material; however, this is not required. Non-limiting materials that can be used include FRP: however, other materials can be used. As can be appreciated, a second inner cryostat wall can be positioned about the first cryostat wall to allow a cooling fluid to flow between the first and second cryostat walls; however, this is not required. The second inner cryostat wall, when used, can be formed of the same materials as the first inner cryostat wall; however, this is not required. In still yet another and/or alternative non-limiting embodiment of the invention, the power cable can include a thermo-insulation material positioned at least partially about one or more of the inner cryostat walls so as to provide additional insulation to the cooling fluid; however, this is not required. Many different types of thermo-insulation materials can be used. In another and/or alternative non-limiting embodiment of the invention, an outer cryostat wall can be positioned at least partially about the thermo-insulation material; however, this is not required. The outer cryostat wall, when used, can be formed of the same or different material from the inner cryostat wall. The outer cryostat wall, when used, provides additional insulation to the cooling fluid. In still another and/or alternative non-limiting embodiment of the invention, the power cable generally includes an outer protective covering to protect the internal components of the power cable. Many different materials can be used for the protective coating (e.g., plastic coating, rubber coating, etc.). Although a power cable for supplying power from a power source to one or more induction coils has been described, it can be appreciated that an induction coil having one or more of the components of the power cable can be used in the present invention. In particular, the present invention contemplates an induction coil that can controllably channel cooling fluid through one or more passageways about the one or more HTS wires of the induction coil so as to coil the one or more HTS wires during operation of the induction coil. 
     In still another and/or alterative non-limiting aspect of the present invention, the induction coil of the present invention can be designed so that a workpiece can be heated or melted when the workpiece is at least partially positioned at or about a center of one or more coiled turns of the induction coil. Such an arrangement is defined as a coreless type induction coil arrangement. The workpiece can be designed to be at least partially passed into or through the coiled turns of the induction coil. Alternatively, the workpiece can be designed to be at least partially positioned within the coiled turns of the induction coil. In one non-limiting embodiment the operating parameters of the coreless type induction coil arrangement can be greater than 60 Hz and greater than 1 kW. In one non-limiting aspect of this embodiment, the coreless type induction coil arrangement is operated at at least 100 Hz. In another non-limiting aspect of this embodiment, the coreless type induction coil arrangement is operated at up to about 100 kHz. In still another non-limiting aspect of this embodiment, the coreless type induction coil arrangement is operated at at least about 25 kW. In yet another non-limiting aspect of this embodiment, the coreless type induction coil arrangement is operated at up to about 12 Megawatts. As can be appreciated, lower or higher watt values can be used for the coreless type induction coil arrangement. 
     In yet another and/or alternative non-limiting aspect of the present invention, the induction coil of the present invention can be designed so that a workpiece can be heated or melted when the workpiece is at least partially positioned or at least partially passed next to one or more induction coils. Such an arrangement is defined as a strip type induction coil arrangement. In one non-limiting embodiment, the operating parameters of the strip type induction coil arrangement can be greater than 60 Hz and greater than 1 kW. In one non-limiting aspect of this embodiment, the strip type induction coil arrangement is operated at at least 100 Hz. In another non-limiting aspect of this embodiment, the strip type induction coil arrangement is operated at up to about 100 kHz. In still another non-limiting aspect of this embodiment, the strip type induction coil arrangement is operated at at least about 1 Megawatt. In still yet another non-limiting aspect of this embodiment, the strip type induction coil arrangement is operated at up to about 6 Megawatts. As can be appreciated, lower or higher watt values can be used for the strip type induction coil arrangement. 
     In one non-limiting object of the present invention is to provide an inductor that uses a superconducting material. 
     In another non-limiting object of the present invention is provided an inductor that uses a High HTS superconductor material. 
     In still another non-limiting object of the present invention is provided an inductor that uses a High HTS superconductor material and operates at at least about 100 Hz and at least about 25 kW. 
     In yet another non-limiting object of the present invention is provided an inductor that includes a specially configured induction coil that includes HTS superconductor material. 
     These and other objects and advantages will become apparent to those skilled in the art upon the reading and following of this description taken together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Reference may now be made to the drawings, which illustrate various embodiments that the invention may take in physical form and in certain parts and arrangements of parts wherein; 
         FIG. 1  illustrates a prior art first generation HTS wire that is in the form of a multi-filamentary composite; 
         FIG. 2  illustrates a second generation HTS wire that is in the form of a coated conductor composite which can be used in the present invention; 
         FIG. 3  illustrates a sectional view of a non-limiting HTS coaxial cold dielectric superconductor cable that can be used in the present invention; 
         FIG. 4  shows schematically a non-limiting embodiment of an apparatus according to the invention; 
         FIG. 5  shows schematically another non-limiting embodiment of an apparatus according to the invention; and, 
         FIGS. 6 and 7  show schematically another non-limiting embodiment of an apparatus according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF NON-LIMITING EMBODIMENTS OF THE INVENTION 
     Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating various embodiments of the invention only, and not for the purpose of limiting the invention, a first generation superconductive wire  10  is illustrated in  FIG. 1 . The first generation superconductive wire included a matrix of superconducting filaments  12  that were encapsulated in a silver alloy  14 . The superconducting filaments are spaced from one another and are formed of a superconducting material that has superconducting properties at temperatures below 77° K. The structure and materials used in the first generation superconductive wire limited the amount of current that could flow through the first generation superconductive wire and the current frequency that could be handled by the first generation superconductive wire. Typically, no more than 60 Hz current frequencies could be successfully passed through the first generation superconductive wire. In addition, the first generation superconductive wire typically could only handle less than about 1 kW of power. These limitations resulted in such first generation superconductive wires being problematic for use in various types of induction heating systems. 
     Referring now to  FIG. 2 , there is illustrated a non-limiting second generation HTS wire  20  which can be used to form a part of an induction coil which can be used in the present invention. The second generation HTS wire  20  is a configuration and is formed of a material that enables the second generation HTS wire to operate at current frequencies exceeding 60 Hz and power levels exceeding 1 kW. The second generation HTS wire is a multilayer wire that includes a base metal layer, a buffer layer, superconductive material, and a top metal layer. As can be appreciated, other layers can be included in the second generation HTS wire  20 . As illustrated in  FIG. 2 , the second generation HTS wire  20  includes abase metal layer  22  that is formed of non-magnetic metals or non-magnetic metal alloys. For example, the base metal layer can be formed of an alloy of nickel and tungsten. The base metal layer is generally the thickest layer of the second generation HTS wire; however, this is not required. Positioned on top of the base metal layer are one or more buffer layers. As illustrated in  FIG. 2 , three buffer layers  24 ,  26 , 28  are included in the second generation HTS wire. As can be appreciated, a larger or smaller number of buffer layers can be used. In one non-limiting example, buffer layer  24  is a yttrium oxide layer, buffer layer  26  is a yttrium-stabilized zirconia layer, and buffer layer  28  is a cerium oxide layer. The thickness of the buffer layers can be the same or different. One or more layers of superconductive material  30  is positioned on the top of buffer layer  28 . Superconductive material is a material that is superconductive at temperatures of 77° K or higher. In one non-limiting example, superconductive material  30  is YBa 2 Cu 3 O 7 . This superconductive material is superconductive to temperatures up to about 92° K. If more than one layer of superconductive material  30  is used, such layers of superconductive material can have the same or different composition and/or thickness. The second generation HTS wire  20  includes a top metal layer  32  that is positioned on top of the one or more layers of superconductive material  30 . The top metal layer includes one or more noble metals and/or one or more noble metal layers. For example, the top metal layer is a silver layer. The top metal layer and the base layer can be used to partially or fully encapsulate the other layers of the second generation HTS wire; however, this is not required. 
     Referring now to  FIG. 3 , there is illustrated one non-limiting configuration of an HTS coaxial cold dielectric superconductor cable  40  that can be used in an induction heating system of the present invention. Superconductor cable  40  typically includes a core, second generation HTS wire positioned at least partially about the core, and an inner cryostat wall spaced from the second generation HTS wire to form a cooling fluid channel between the inner cryostat wall and the second generation HTS wire. As can be appreciated, the HTS coaxial cold dielectric superconductor cable  40  can include additional layers. As illustrated in  FIG. 3 , superconductor cable  40  includes a metal core  42 . Metal core  42  is generally formed of an electrically conductive material and a non-magnetic material; however, this is not required. For example, the metal core can be formed of a copper wire or copper cable. Wrapped about core  42  are two layers of second generation HTS wire  20 . Positioned about the second generation HTS wire is a high voltage dielectric material  44 . The high voltage dielectric material is used to at least partially electrically insulate the second generation HTS wires from the outer layers of the superconductive coil. One or more layers of shielding wire and/or tape can be positioned about the high voltage dielectric material. As illustrated in  FIG. 3 , an HTS shield tape  46  is positioned about high voltage dielectric material  44  and a copper shield wire  48  is positioned about the HTS shield tape  46 . An inner cryostat wall  50  is positioned about, and at least partially spaced from the copper shield wire  48 . A plurality of spacers  52  can be used to maintain the spacing between the copper shield wire  48  and the inner cryostat wall  50 ; however, this is not required. The space between the copper shield wire  48  and the inner cryostat wall  50  forms a passageway for a cooling fluid (e.g., liquid nitrogen, etc.) to at least partially flow about and cool one or more of the electrically conductive components of the superconductive cable  40  (i.e. metal core  42 , second generation HTS wire  20 , etc.). Positioned about the inner cryostat wall  50  is a thermo-insulation material  54  that can be used to provide additional insulation to the cooling fluid that is used to cool the electrically conductive components of the superconductive cable  40 . An outer cryostat wall  56  can be positioned at least partially about the thermo-insulation material  54  to provide additional insulation to the cooling fluid. An outer protective covering  58  can be positioned about the outer cryostat wall  56  to protect the internal components of the superconductive coil  40 . 
     Referring now to  FIGS. 4-7 , various non-limiting configurations of induction heating systems in accordance with the present invention are illustrated. Referring now to  FIG. 4 , induction heating apparatus  100  is designed to heat a workpiece or blank  110 . The workpiece can be designed to partially or continuously move through apparatus  100  during the heating process, be maintained in position during the heating process, or be rotated during the heating process. Apparatus  100  includes a chamber  120  that has a cavity or passageway  122 . The cavity of passageway  122  can be positioned through the middle of the chamber; however, this is not required. The cavity or passageway  122  is designed to at least partially receive workpiece or blank  110 . Chamber  120  also includes a cooling cavity  124  that is partially or fully positioned about cavity or passageway  122 . One or more superconductive cables  40  or one or more second generation HTS wires  20  are positioned in the cooling cavity and are at least partially wrapped at least partially around cavity or passageway  122  and at least partially along the length of cavity or passageway  122 . The one or more superconductive cables  40  or one or more second generation HTS wires  20  are connected by power cables  136 ,  138  to a high frequency power source  130  (e.g., 70 Hz-100 kHz &amp; 1 kW-12 Megawatts, etc.). These power cables can include one or more HTS wires; however, this is not required. In one non-limiting designed, power cable  136  is similar in design to superconductive cable  40 . Power cable  136 , when similar in design to superconductive cable  40 , can be cooled by a cooling liquid. In another or additional design, power cable  138  is also similar in design to superconductive cable  40 . Power cable  138 , when similar in design to superconductive cable  40 , can also be cooled by a cooling liquid. The high frequency power source can include voltage controllers/monitors  132  and/or amperage controllers/monitors  134 . The one or more superconductive cables  40  or one or more second generation HTS wires  20  are at least partially cooled during the operation of the induction heating system by flowing a cooling fluid (e.g., liquid nitrogen, etc.) through cooling cavity  124 . As indicated by the flow arrows, a liquid nitrogen recirculation system  140  causes liquid nitrogen to flow into cooling cavity  124  via pipe  142  and from cooling cavity  124  to liquid nitrogen recirculation system  140  via pipe  144 . 
     During operation of the induction heating apparatus  100 , current flows through the one or more superconductive cables  40  or one or more second generation HTS wires  20  to set up an electrical field that induces currents in the workpiece or blank  110  thereby causing the workpiece or blank  110  to be heated. 
     Referring now to  FIG. 5 , a modification of the induction heating apparatus  100  is illustrated.  FIG. 5  illustrates an induction heated crucible  200  that is used to heat or melt material in the crucible  210 . Crucible  210  includes a melting cavity  220  that is used to contain materials  222  to be melted or heated by induction heated crucible  200 . Crucible  210  also includes a cooling cavity  230  that is partially or fully positioned about melting cavity  220 . One or more superconductive cables  40  or one or more second generation HTS wires  20  are positioned in the cooling cavity and are at least partially wrapped at least partially around melting cavity  220  and at least partially along the length of melting cavity  220 . The one or more superconductive cables  40  or one or more second generation HTS wires  20  are connected by power cables  240 ,  242  to a high frequency power source, not shown. These power cables can include one or more HTS wires; however, this is not required. In one non-limiting design, power cable  240  is similar in design to superconductive cable  40 . Power cable  240 , when similar in design to superconductive cable  40 , can be cooled by a cooling liquid. In another or additional design, power cable  242  is also similar in design to superconductive cable  40 . Power cable  242 , when similar in design to superconductive cable  40 , can also be cooled by a cooling liquid. The high frequency power source can include voltage controllers/monitors and/or amperage controllers/monitors. The one or more superconductive cables  40  or one or more second generation HTS wires  20  are at least partially cooled during the operation of the induction heated crucible by flowing a cooling fluid (e.g., liquid nitrogen, etc.) through cooling cavity  230 . As indicated by the flow arrows, a liquid nitrogen recirculation system, not shown, causes liquid nitrogen to flow into cooling cavity  230  via pipe  250  and from cooling cavity  230  to the liquid nitrogen recirculation system via pipe  252 . 
     During operation of induction heated crucible  200 , current flows through the one or more superconductive cables  40  or one or more second generation HTS wires  20  to set up an electrical field that induces currents in material  222  thereby causing the materials to be heated or melted. 
     Referring now to  FIGS. 6 and 7 , another induction heating apparatus  300  is illustrated. The induction heating apparatus includes a cooling chamber  310 . Positioned in the cooling chamber is one or more superconductive cables  40  or one or more second generation HTS wires  20 . The one or more superconductive cables  40  or one or more second generation HTS wires  20  are connected by power cables  320 ,  322  to a high frequency power source, not shown. These power cables can include one or more HTS wires; however, this is not required. In one non-limiting design, power cable  320  is similar in design to superconductive cable  40 . Power cable  320 , when similar in design to superconductive cable  40 , can be cooled by a cooling liquid. In another or additional design, power cable  322  is also similar in design to superconductive cable  40 . Power cable  322 , when similar in design to superconductive cable  40 , can also be cooled by a cooling liquid. The high frequency power source can include voltage controllers/monitors and/or amperage controllers/monitors. The one or more superconductive cables  40  or one or more second generation HTS wires  20  are at least partially cooled during the operation of the induction heating apparatus by flowing a cooling fluid (e.g., liquid nitrogen, etc.) through cooling chamber  310 . As indicated by the flow arrows, a liquid nitrogen recirculation system, not shown, causes liquid nitrogen to flow into cooling chamber  310  via pipe  330  and from cooling chamber  310  to the liquid nitrogen recirculation system via pipe  332 . 
     During operation of the induction heating apparatus  300 , current flows through the one or more superconductive cables  40  or one or more second generation HTS wires  20  to set up an electrical field that induces currents in a plate or workpiece  340  thereby causing the plate or workpiece to be heated or melted. As illustrated by the arrow in  FIG. 7 , the plate or workpiece  340  can be moved relative to the cooling chamber. As also illustrated in  FIGS. 6 and 7 , the plate or workpiece are positioned adjacent to the cooling chamber during the heating of the plate or workpiece. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the constructions set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The invention has been described with reference to preferred and alternate embodiments. Modifications and alterations will become apparent to those skilled in the art upon reading and understanding the detailed discussion of the invention provided herein. This invention is intended to include all such modifications and alterations insofar as they come within the scope of the present invention. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween. The invention has been described with reference to the preferred embodiments. These and other modifications of the preferred embodiments as well as other embodiments of the invention will be obvious from the disclosure herein, whereby the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.