Patent Number: 059237163
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the various figures of the drawing wherein like reference characters refer to like parts, there is shown in FIG. 1 a schematic cross-sectional side view of a plasma extrusion dynamo 2 of the present invention showing the applied and current loop fields separately. In the present invention, the continuous extrusion of plasma through a converging magnetic nozzle forms a stationary, steady-state current loop 15 within the moving plasma stream 14 as hereinafter described. In an exemplary embodiment, the plasma extrusion dynamo 2 of the present invention includes a plurality of nozzle coils 12 that are configured to produce the converging field lines 11. While two coils are illustrated, this is not a limitation. It is with the skill of those knowledgeable in the art to adjust the strength, size and number (i.e., at least one) of the coils to provide the desired magnetic field so as to create the desired annular current flow path 15 in the moving plasma flow 14. For example, the nozzle coils can be arranged alone or in combination with ferromagnetic structures to produce the converging magnetic fields. Also, the nozzle coils can be arranged to generate funnel like converging magnetic fields that present any of a number of cross sections, including circular, elliptical, oval and polygonal cross sections, that will produce a closed current loop 15 responsive to the flowing conductive plasma. Preferably, the magnetic field being generated by the nozzle coils 12 is a converging conical magnetic field so as to form a nozzle or inlet region that receives the plasma flow 14. In the illustrated embodiment, the nozzle coils 12 are direct current electromagnetic coils. Alternatively, the nozzle coils can be superconducting coils or permanent magnets. Further, ferromagnetic structures such as iron, disposed outside the plasma, can be used to concentrate or guide the magnetic fields being generated by the nozzle coils 12 to produce a magnetic field have the desired cross section and strength. As described in specific fusion reactor embodiments below (see FIGS. 3-4), a neutral fuel 32 is converted into a conductive plasma using any one of a number of techniques known in the art, as well as using the heat and radiation from continuous fusion reactions. The conductive plasma being presented to the converging magnetic field is a pressurized conductive plasma flow so as to form a high pressure region 10 upstream of the nozzle region. The conductive plasma flows towards the converging field lines 11 formed by the set of direct current carrying nozzle coils 12 to a lower pressure exhaust region 13. The nozzle or inlet region is formed by the converging magnetic field lines 11 such as those near the center of a circular current loop 15. The plasma flow 14 intersects the converging field lines 11 and crosses the radial components of the field. The crossing of the magnetic field lines 11 by a conductive fluid such as the plasma flow 14 is resisted if the field and plasma geometry is such that a sustained current is free to flow in the fluid in a direction perpendicular to the plane defined by the magnetic field lines and the plasma pressure gradient. More particularly, the crossing of the field lines by the plasma flow 14 generates a circularly polarized voltage and current loop 15 surrounding or about the axis 16 of the nozzle and plasma extrusion dynamo 2. Because the plasma current loop 15 interacts with the radial nozzle field components to retard the flow, a pressure gradient between the upstream and downstream side of the nozzle is required to maintain the flow of plasma. The current loop 15 in the plasma also interacts with the axial components of the magnetic field lines 11 in the nozzle region to generate radially inward forces 18 that tend to squeeze the plasma current loop to a smaller diameter. The squeezing forces 18 are resisted by plasma pressure as well as by the mutual magnetic repulsion of the opposite sides of the plasma current loop 15. The resistive plasma continues to flow and cross the nozzle field lines. The new plasma entering behind it interacts in turn with the magnetic field in the nozzle region and renews the plasma current loop. The result is a steady plasma extrusion flow through the nozzle that generates a steady-state, stationary current loop 15 for an indefinite period of time. The flow energy sustains the current against resistive losses. At higher plasma temperatures the lower plasma resistivity reduces the losses and consequently reduces the required flow rate. In sum, the conditions are such that the plasma flow is retarded by the field lines 11 and a current loop 15 is formed in the nozzle region of the magnetic field. The current loop 15 interaction with the radial components of the field lines 11 produces axial retarding forces 17, and the interaction with the axial field lines produces radial squeeze forces 18. The retarding forces 17 and the radial squeeze forces 18 act to retard the plasma flow 14 and compress the plasma to a smaller diameter. This occurs because the plasma particles are the charge carriers that form the current and experience the electromagnetic field forces. The current loop 15 generates a poloidal magnetic field 19, i.e., a set of closed poloidal magnetic flux loops, that extends along the circumferential length of the current loop 15. This poloidal magnetic field 19 has three effects. First, it encloses a toroidal plasma volume with closed field lines 20 (FIG. 2) which tend to contain the plasma particles. Second, the plasma current loop charge carriers interact with the poloidal field and are compressed toward the center of the current path cross-section through a pinch effect. This pinched center forms the fusion reaction zone. Third, the current loop interacts with itself through the poloidal field to expand the loop and resist the radial squeeze forces 18. The pinched plasma also is contained so it is far from any physical walls so as to sustain nuclear fusion reaction conditions. Under steady-state conditions the current loop 15 will reach an equilibrium size and current level that depends on the applied pressure gradient for the plasma flow and the strength and geometry of the magnetic nozzle field 11. Plasma particles, acting as current charge carriers, will loose momentum in the current carrying direction through collisions (the normal electrical resistance effect), and flow toward the exhaust under the influence of the pressure gradient. The motion across the field lines 11 will cause the plasma particles to again become current loop charge carriers, but in a path closer to the exhaust. The net result of this process is a pressure driven flow through the magnetic nozzle which maintains a steady-state current flow through dynamo action which balances resistive losses. It should be noted that while there is a plasma flow through the magnetic nozzle under steady-state conditions, the current loop is stationary with respect to the nozzle coils 12 and the axis 16. This flow-through effect provides an automatic means of adding fresh fuel to the reaction zone and removing reaction products. Second order interactions such as flux relaxation may convert some of the poloidal flux 19 to toroidal flux parallel to the current loop 15. This will result in a more stable flux configuration. The form of the plasma toroid depends on the design of the magnetic nozzle. If radial field lines dominate, a relatively force-free toroid resembling a spheromak will result. If axial flux lines dominate, a tightly squeezed structure will be formed which resembles a theta pinch toroid. Referring now to FIG. 2, there is shown a schematic cross-sectional side view of the plasma extrusion dynamo 2 of FIG. 1 showing the resultant of the nozzle field 11 and the current loop poloidal field 19. As shown, the closed field lines 20 of the poloidal field 19 encloses the current loop 15 and forms a toroidal volume 21. As indicated above, the interaction of the plasma current loop 15 with its own poloidal magnetic field 19 compresses the plasma in the toroidal volume 21 toward the toroid section axis through the pinch effect. The closed field lines 20 forming the toroidal volume 21 retard the plasma in the high pressure region 10 from flowing directly to the lower pressure exhaust region 13. As such, the toroidal volume 21 acts in effect acts as a flow retarding device. The closed field lines 20 also present a converging field region 24 to the high pressure region 10 which is similar to converging field generated by the nozzle coils 12, but which is smaller and of opposite polarity. The converging region 24 tends to retard flow through the center of the toroidal volume 21 thereby enhancing the flow retarding performance of the toroidal volume 21. The border between the closed poloidal field lines 20 of the current loop 15 and the surrounding open field lines 23 generated by the nozzle coils 12, is typically referred to as the separatrix 22. The relative position of the separatrix 22 with respect to the axis 16 is a function of both the velocity of the plasma flow 14 and the strength of the nozzle coil generated magnetic field. For example, the diameter of the current loop 15 can be increased by increasing the velocity of the plasma flow 14 and, correspondingly, the diameter can be decreased by increasing the strength of the nozzle coil generated magnetic field. Now referring to FIG. 3, there is shown a schematic cross-sectional side view of one embodiment of a fusion reactor 100 with a plasma extrusion dynamo 2 of the present invention. The fusion reactor 100 includes a plasma extrusion dynamo 2 of the present invention, a means 102 for providing the pressurized plasma, an housing 104 and a vacuum pump 106. In terms of a fusion reactor, the conductive plasma is deuterium, tritium or any other element known in the art, or any combination of elements thereof, that can release energy as a result of a nuclear fusion reaction. The reactor also includes means (not shown) for capturing the energy generated by the fusion reactions so useable energy (e.g., electricity) can be provided to consumers. Reference also should be made to the foregoing for any item not specifically described hereinafter. The means 102 for providing the pressurized plasma 102 includes a plasma jet 31 that forms and accelerates the high velocity plasma 30 towards the nozzle region of the converging magnetic field lines 11 set up by the nozzle coils 12. The plasma jet 31 using known principles or techniques, e.g., arc discharge, converts neutral fuel 32 (e.g., deuterium) into a high velocity plasma stream using electric power 33 as an energy source. The plasma jet 31, the nozzle coils 12, the stagnation pressure zone 34, and the exhaust region 13 are enclosed in an impermeable vessel or housing 104. A vacuum pump 106 and associated exhaust piping is fluidically interconnected to the interior of this impermeable vessel or housing 104 so as to remove the exhaust gas and fusion reaction by-products as well as maintaining the low pressure conditions required for reactor operation. The impermeable vessel or housing may be manufactured from any of a number for materials, or combination of materials, as is known in the art that are adequate for the intended use and environmental conditions, e.g., a gas impermeable metallic shell with a ceramic or graphite lining. The vacuum pump 106 may be any of a number of known vacuum pumps or vacuum pumping systems that can maintain the required low pressure conditions within the housing 104 and capable of removing fusion reaction by-products and/or exhaust gases. For example, a system including a mechanical type of vacuum pump and a diffusion type of vacuum pump can be used to evacuate the housing interior and maintain a continuing exhaust process. The high velocity plasma jet 30 interacts with the converging nozzle field lines 11 and is decelerated, forming a high pressure stagnation region 34 upstream of the nozzle. The high pressure of the stagnation pressure zone 34 causes plasma to flow towards the lower pressure exhaust region 13. This flow of plasma, as previously described above, as it crosses the magnetic field lines 11 generates a current loop 15 for fusion reaction containment. The stagnation zone 34 and the continuous replenishment of conductive plasma from the high velocity plasma jet 30 assures a constant source of flowing plasma to maintain the current loop 15 as well as to create the conditions conducive to fusion reactions. Now referring to FIG. 4, there is shown a schematic cross-sectional side view of another embodiment of a fusion reactor 200 that is configured with two plasma extrusion dynamos 2,2' of the present invention having a common supply chamber 202. Reference should also be made to the foregoing for any item or feature not specifically described hereinafter. Also, in the following certain reference numerals have been provided with and without a "'" (e.g., 2 and 2') to distinguish the corresponding components of, and the two plasma extrusion dynamos 2,2'. Unless otherwise indicated in the following, the above described characteristics and features apply equally to the corresponding components and/or the dynamos. In operation, neutral fuel 32 is injected into the central volume of the common supply chamber 202, wherein it is converted to a relatively high pressure, relatively low temperature plasma 40. Microwaves 203, neutral beams or other known means of heating neutral material to form plasma can be supplied from an outside source to start or sustain the process. Preferably, the radiation 44 from fusion reactions supplies most or all of the plasma formation energy in steady-state operation. Each pair of direct current carrying nozzle coils 12,12' of the respective plasma extrusion dynamos 2,2' are placed back-to-back on a common axis 205. Both nozzle coils 12,12' are energized with a current in the same rotational direction so the converging nozzle fields 11,11' join and surround the central volume of the common supply chamber 202 with a common field 206. A separator coil 207 is placed midway between the nozzle coils, and centered on their common axis 205. The separator coil 207 is energized with a current in the same rotational direction as is used to energize the nozzle coils 12,12'. The separator coil 207 contributes to the common field 206 and has other functions that are described below. As with the first fusion reactor embodiment described above, the fusion reactor 200 also includes a housing 104 and a vacuum pump 106. The impermeable vessel or housing 104 surrounds both of the extrusion dynamos 2,2' including both sets of nozzle coils 12,12', the common supply chamber 202, and separator coil 207. The vacuum pump 106 and the associated exhaust piping 209 or ducts are fluidically interconnected to the interior of the impermeable vessel or housing 104 so as to remove the exhaust gas and fusion reaction byproducts as well as to maintain the low pressure conditions required for reactor operation. The plasma 40 in the common supply chamber 202 is at relatively high pressure, and flows to the lower pressure exhaust regions 13,13' defined for the respective extrusion dynamos. As described in the foregoing, the plasma flow crosses the field lines 11,11' and generates current loops 15,15' for fusion reaction containment in each of the plasma extrusion dynamos. Because the plasma current loops 15,15' have parallel currents, the magnetic fields of each will have a tendency to attract each other creating the potential for merging the two current loops. Such a merger would disrupt the dynamo process in at least one of the two magnetic nozzles. The separator coil 207, preferably carries current anti-parallel to that in the plasma current loops 15,15' to repel the current loops thereby preventing merger. The separator coil 207 also clamps the plasma current loops 15,15' between anti-parallel coils to reduce their tendency to rotate about an axis perpendicular to the axis 205 common to the extrusion dynamos 2,2'. Although a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.