Abstract:
The present invention discloses systems and methods for electromagnetic spacecraft propulsion or thrust generation without the expulsion of reaction mass. The systems include capacitor assemblies with a switch-controlled conductive discharge path, a means of charging the capacitor assemblies, a means of generating magnetic fields using electromagnetic coils, and a means for periodically shaping the intensity, duration and polarity of magnetic fields from the coils. Thrust is generated through the interaction of the shaped magnetic fields and the segmented current in the conductive discharge path during capacitor discharge.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention discloses systems and methods for electromagnetic spacecraft propulsion or thrust generation. In particular, thrust is generated without the expulsion of reaction mass. These unique systems and methods are comprised of capacitor assemblies with switch-controlled discharge elements and electromagnetic coils. The thrust is generated through the interaction of shaped magnetic fields from the coils and the current in the discharge element of the capacitor during discharge. 
       BACKGROUND OF THE INVENTION 
       [0002]    A major issue facing future space exploration is advanced propulsion technologies. The combination of reaction mass and engine mass in traditional propulsion systems imposes practical limits to space missions. NASA and the space exploration community have addressed this problem by identifying and developing new propulsion concepts requiring either minimal or no propellant mass. The result has been the development of electric ion thrusters with high specific impulse and thus low reaction mass, and field effect propulsion systems, or propellantless propulsion, requiring no reaction mass. 
         [0003]    Specific impulse, which is the ratio of thrust produced to the rate of propellant consumed, is one of the most significant metrics for a space propulsion system. Specific impulse has units of seconds, and is essentially the number of seconds that a pound of propellant will produce a pound of thrust. The higher the specific impulse the lower the required propellant mass for a given space mission. Current space propulsion systems have a specific impulse range from 300 seconds to 10,000 seconds, with thrust level being generally inversely proportional to specific impulse. By way of example for comparison, the LOX-H2 space shuttle main engines have a specific impulse of about 450 s, nuclear thermal rockets about 900 s, electric ion and magnetic plasma engines range from 5000 s-9000 s. 
         [0004]    Table 1 compares several contemporary high specific impulse space propulsion systems, including vacuum arc, Hall Effect, and magnetoplasma engines. One type of Hall effect thruster is described, for example, in U.S. Pat. No. 8,468,794 issued to Patterson, which is the basis for the HiVHAC device. U.S. Pat. No. 7,053,333 issued to Schein et al. describes the AASC vacuum arc thruster, while U.S. Pat. No. 6,334,302 issued to Chang-Diaz describes the VASIMR magnetoplasma ion thruster. Such systems are very fuel efficient; however, they require both a reaction mass and large amounts of power; typically 1 kWe per 0.030-0.040 Newtons thrust for ion thrusters, and 1 kWe per 0.050-0.080 Newtons thrust for Hall-effect thrusters. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Device 
                 Thrust (mN) 
                 Power (kW) 
                 Isp (sec) 
                 propellant 
                 type 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 AASC-VAT 
                 0.125 
                 0.010 
                 1500 
                 Metal ion 
                 Vacuum arc 
               
               
                 NASA PPT 
                 0.86 
                 0.07 
                 1370 
                 Teflon 
                 Pulsed plasma 
               
               
                 NSTAR 
                 92 
                 2.3 
                 3300 
                 Xe 
                 Electrostatic 
               
               
                 HiVHAC 
                 150 
                 3.6 
                 2800 
                 Xe 
                 Hall effect 
               
               
                 VASIMIR VX-200 
                 5000 
                 200 
                 5000 
                 Ar 
                 magnetoplasma 
               
               
                   
               
             
          
         
       
     
       Prior Art for Propellantless Electromagnetic Propulsion 
       [0005]    Field propulsion, or propellantless propulsion, employs electromagnetic field effects for generating propulsion forces, expels no reaction mass, and therefore effectively has an infinite specific impulse. Recent experimental investigations validated by NASA have demonstrated apparent validity of field propulsion. 
         [0006]    Table 2 presents a comparison of experimental results for several propellantless propulsion devices. As disclosed in U.S. Pat. Nos. 2,949,550 and 3,187,206 to T. T. Brown, through an electrokinetic phenomenon termed the Biefeld-Brown Effect, electrical energy input into asymmetrical capacitors can be converted to mechanical energy which then provides a force for propelling an object. NASA is still investigating the use of Brown&#39;s discovery, as disclosed in U.S. Pat. No. 6,317,310 to Campbell. Another such device is disclosed in U.S. Pat. No. 6,492,784 to Serrano, which generates the Biefeld-Brown Effect using stacked-disc asymmetrical capacitors. Debate is ongoing in the literature as to whether the Biefeld-Brown Effect will work in the vacuum of space. Another limitation to using the effect may be the scalability potential, since asymmetrical capacitor devices to date have only generated tens of milli-newtons of thrust from tens of watts of input power. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Thrust 
                   
                 Isp 
                   
               
               
                 Device 
                 (mN) 
                 Power (kW) 
                 (sec) 
                 propellant 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Biefeld-Brown Effect 
                 0.05 
                 0.035 
                 Infinite 
                 none 
               
               
                 Fetta-Cannae Drive 
                 0.01 
                 0.0105 
                 Infinite 
                 none 
               
               
                 NASA-EM test 
                 0.09 
                 0.017 
                 Infinite 
                 none 
               
               
                 China-EM 
                 720 
                 2.5 
                 Infinite 
                 none 
               
               
                   
               
             
          
         
       
     
         [0007]    Other propellantless propulsion concepts are under development. Electrodynamic structures, as disclosed in U.S. Pat. No. 7,913,954 to Levin, include a power system, a plurality of collectors, a plurality of emitters, and conductive paths for moving payloads through the Earth&#39;s magnetic field. An inertial propulsion device, as disclosed in U.S. Pat. No. 8,066,226 to Fiala, utilizes several interconnected gyroscopic elements and Earth&#39;s gravity field to move without propellant. The superconducting electromagnetic turbine, as disclosed in U.S. Pat. No. 8,575,790 to Ogilvie, uses a pair of counter-rotating electrodynamic superconductor rotors to displace the surrounding geomagnetic field. These devices do not have general space-based utility since they are restricted to operations within either the gravity field or the magnetic field of Earth. 
         [0008]    The most current example of a propellantless field propulsion system is an electromagnetic drive system as disclosed in U.S. Pat. Appl. No. 20140013724 to Fetta, based on prior work in the UK and experiments in China. This system includes an axially-asymmetric resonant cavity with a conductive inner surface adapted to support a standing electromagnetic (EM) wave. The resonating cavity lacks second-axis axial symmetry, thereby causing the standing EM wave to induce a net unidirectional force on the resonant cavity, thus generating thrust without reaction mass. Experimental versions of these EM devices have reportedly produced thrust levels of micro-newtons up to milli-newtons from several kilowatts of input power, as noted in Table 2. 
       Scientific Basis for the Invention 
       [0009]    It is the objective of the current disclosure to present systems and methods for generating an unbalanced Lorentz force due to magnetic field interactions between electromagnetic coils and a segmented current in a conductor between two oppositely charged capacitor elements configured in a specific geometric arrangement. This combination of geometry and magnetic field interaction produces thrust without expelling propellant. 
         [0010]    By way of background, and with reference initially to  FIG. 1 , it is well known to those skilled in the art of classical electrodynamics that a charged particle  1 , with velocity vector  3  parallel to the x-axis as shown, moving through magnetic field  2  which is parallel to the y-axis, will experience a Lorentz force component  4  parallel to the z-axis. The necessary equations to calculate the force magnitude and direction are well known in the current physics literature. 
         [0011]    By way of further background, the situation presented in  FIG. 2  is also well known to those skilled in the art and familiar with the works of Feynman and Tipler. The figure illustrates two positively charged coplanar particles  8  and  9  moving with respective orthogonal velocities  10  and  11 , with velocity vector  10  being parallel to the y-axis of the coordinate system shown, and velocity vector  11  being parallel to the x-axis. At the instant shown, particle  8  induces a magnetic field  12  on particle  9 , while particle  9  induces no magnetic field effect on particle  8 . As a result, a Lorentz force component  4  acts on particle  9 , while no similar force acts on particle  8 . This situation has been well-studied in the literature, both as an apparent violation of Newton&#39;s Third Law and as a potential for devising a propellantless propulsion device. However, experimental attempts to date have the charged particles confined in conductors as part of a continuous current loop. When all forces are properly accounted for on the continuous current loops, no net unbalanced system force is produced on the system. 
         [0012]    By way of further background, and with reference to  FIG. 3 , it is also well known to those skilled in the art that segments of two parallel conductors  5  each carrying a current  7  in the same direction will experience equal and opposite forces  4  as shown. The necessary equations to calculate the force magnitude per unit length of conductor are well known in the current physics literature. 
         [0013]    By way of further background with reference to  FIG. 4 , the single particle physics of  FIG. 2  is expanded to apply to two discrete segments of perpendicular conductors  5  and  6  each carrying currents  7 . It is well known to those skilled in the art that the segments will experience an unbalanced Lorentz force component  4  as shown. The necessary equations to calculate the force magnitude per unit length of conductor are well known in the current physics literature. 
         [0014]    It is the purpose of the present invention to exploit the unbalanced Lorentz force situation of  FIG. 4  by producing a current segment that is not part of a continuous current loop. With reference to  FIG. 5 , an electromagnetic coil  15  is positioned such that the axis of symmetry of the coil is in the direction of the y-axis of the coordinate system shown. When energized, the coil  15  produces a magnetic field  2  with strongest vector component along the y-axis, which is the axis of symmetry of the coil  15 . A current segment  5  carrying current  7  is placed parallel to the x-direction such that it is perpendicular to the axis of symmetry of the coil  15  as shown. When coil  15  is energized to produce field  2 , a net unbalanced Lorentz force  4  is induced on the system comprised of segment  5  and coil  15 . This unbalanced force arises from the fact that most individual electrons comprising the current moving in the conducting coils of the electromagnet have z-axis velocity components which are orthogonal to the x-axis velocities of each charge in the current  7 . For each coil  15 -current  7  electron pair wherein a z-axis velocity component exists, the situation of  FIG. 2  is realized. Because the charges on the current segment  5  are a discrete packet and are not part of a continuous current loop, there is thus a net force realized on the system comprising the segment and coil. Comprehensive engineering calculations have verified that a net force is produced on the coil-current segment system, while reaction momentum is carried away by the electromagnetic fields in accordance with currently understood principles of modern physics. 
         [0015]    With reference to  FIG. 6 , the situation of  FIG. 5  is generalized to illustrate that the current segment  5  may be created as a conductive discharge element  31  between two oppositely charged elements of a capacitor. An electromagnetic coil  15  is positioned such that the axis of symmetry of the coil is in the plane of the discharge conductor  31 . When coil  15  is energized, magnetic field  2  produces components  6  which are perpendicular to discharge element  31 . The interaction of field  6  and the current in discharge element  31  results in an unbalanced Lorentz force acting on the coil-conductor system which is perpendicular to the plane formed by element  31  and the axis of symmetry of coil  15 . 
         [0016]    The result of  FIG. 6 , based on known physics illustrated in  FIGS. 1-5  and the segmented current loop innovation, comprises the scientific basis for the current invention. It is the purpose of the present invention to exploit the situation illustrated in  FIG. 6 . Appropriate geometric designs with segmented current discharge paths  6  between oppositely-charged capacitor elements are exposed to external magnetic fields from electromagnetic coils in various embodiments such that unbalanced Lorentz forces are produced on the system, thereby producing thrust without expelling propellant. 
       SUMMARY OF THE INVENTION 
       [0017]    It is the objective of the current disclosure to present systems and methods for exploiting the interaction of shaped magnetic fields and an isolated segment of a current-carrying conductor. The basic principle of the current invention is to position electromagnetic coils such that the axes of symmetry of the coils are perpendicular to a current-carrying conductor which is a discharge path between two oppositely-charged capacitor elements. The field interactions occur in such a geometric manner so as to produce a force without expelling propellant. 
         [0018]    Embodiments of the present invention generate thrust without the use of reaction mass or propellant, and do so in a manner distinct from the devices and methods of Brown, Campbell, Serrano, Fetta, and others as mentioned above. Engineering calculations indicate that the present invention is scalable for general space-based applications. This invention is a significant improvement in options for producing variable force and moment components as compared to other such spacecraft propulsion devices. In addition to space-based applications, embodiments of the present invention may also be used to generate thrust in terrestrial applications. 
         [0019]    An exemplary embodiment of the present invention is an electromagnetic thruster, including: multiple capacitor assemblies each composed of two oppositely charged elements with or without a dielectric, a switch-controlled conductive discharge element, a means to charge the capacitor assembly, multiple electromagnetic coils positioned with axes of symmetry perpendicular to the discharge element, and a means to generate magnetic fields with varying polarity, intensity and duration from the electromagnetic coils. Engineering baseline calculations indicate that such an embodiment using a cylindrical capacitor assembly with charging voltage up to twenty kilovolts can generate thrust levels on the order of those shown in Table 2. In complete system comparisons with existing high specific impulse electric thrusters and experimental field propulsion units of the same thrust ranges, this invention has the advantages of minimal engineering and electric power supply complexity for producing thrust without expelling propellant. Moreover, this invention is capable of a full throttle range simply by either controlling or varying the field strength of the electromagnetic coils, or by varying the amplitude of the discharge current. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The accompanying drawings, which are incorporated in and form part of the specification, illustrate various principles of operation and examples of the present invention, including a preferred embodiment of the invention, as well as alternate embodiments, and, together with the detailed description, serve to explain the principles of the invention. 
           [0021]      FIG. 1  is a schematic diagram illustrating the Lorentz force acting on a charged particle moving through a magnetic field; 
           [0022]      FIG. 2  is a schematic diagram illustrating the unbalanced Lorentz force acting on charged particles moving orthogonally in the same plane; 
           [0023]      FIG. 3  is a schematic diagram illustrating the mutual Lorentz forces acting on segments of parallel conductors; 
           [0024]      FIG. 4  is a schematic diagram illustrating the unbalanced force Lorentz force acting on one segment of two orthogonal conductor segments; 
           [0025]      FIG. 5  is a schematic diagram illustrating the Lorentz force on a conductor segment due to a perpendicular magnetic field; 
           [0026]      FIG. 6  is a schematic diagram illustrating the magnetic field distribution induced on a capacitor discharge element by a perpendicular electromagnetic coil; 
           [0027]      FIGS. 7A and 7B  are schematic diagrams illustrating charging and discharging of a capacitor assembly; 
           [0028]      FIG. 8  is a schematic diagram illustrating the magnetic field induced on the discharge element of a capacitor assembly by a Helmholtz coil configuration; 
           [0029]      FIG. 9  is a schematic diagram illustrating a planar capacitor assembly with Helmholtz coils for producing longitudinal thrust; 
           [0030]      FIG. 10  is a schematic diagram illustrating a cylindrical capacitor assembly with Helmholtz coils for producing longitudinal thrust; 
           [0031]      FIG. 11  is a schematic diagram illustrating the use of three radial Helmholtz coil-capacitor assemblies to produce an axial thrust and torque; 
           [0032]      FIG. 12  is a schematic diagram illustrating the use of three circumferentially tangent Helmholtz coil-capacitor assemblies to produce an axial thrust and torque; 
           [0033]      FIG. 13  is a schematic diagram illustrating the use of three capacitor assemblies and six perpendicular electromagnets to produce both axial thrust, planar thrust and torque; 
           [0034]      FIGS. 14A and 14B  are schematic diagrams illustrating a parallel plate capacitor assembly and rectangular electromagnetic coils used to produce a longitudinal thrust; 
           [0035]      FIG. 15  is a schematic diagram illustrating planar capacitor assemblies inside a toroidal electromagnetic solenoid used to produce an axial thrust; 
           [0036]      FIGS. 16A and 16B  are schematic diagrams illustrating the charge-discharge configurations of a capacitor assembly with dielectrics; 
           [0037]      FIG. 17  is a schematic diagram illustrating the use of three capacitor assembly configurations from  FIGS. 16A and 16B  to produce axial thrust; 
           [0038]      FIG. 18  is a schematic diagram illustrating the use of one embodiment of the present invention to propel a solar-powered spacecraft. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
         [0040]    The basic operating principle of the present invention is illustrated in  FIGS. 7A and 7B . In  FIG. 7A , a voltage source  18  is connected through closed charge switches  14  so as to induce opposite charges on capacitor assembly elements  32  and  33 . Discharge switches  16  are open, and electromagnetic coil  15  is not energized. In  FIG. 7B , the voltage source  18  is disconnected by opening charge switches  14  so as to isolate the charges on capacitor assembly elements  32  and  33 . Electromagnetic coil  15  is energized to produce the perpendicular magnetic field components  6  on discharge element  31  in the direction of field vector  2 . Discharge switches  16  are then closed, and a current is produced in discharge element  31  as the capacitor discharges. The interaction of the magnetic field  6  with the current in discharge element  31  results in an unbalanced Lorentz force on the system because the electric circuit is not continuous. When elements  32 ,  33  are sufficiently discharged, the process is repeated. 
         [0041]    With reference to  FIG. 8 , a refinement of the basic embodiment from  FIGS. 7A and 7B  is illustrated wherein two electromagnetic coils  15  are positioned in a Helmholtz coil configuration. This produces a stronger and more uniform magnetic field distribution  6  acting as shown on discharge element  31  during capacitor discharge. 
         [0042]    With reference to  FIGS. 9 and 10 , two of the many geometric possibilities for capacitor assembly design are illustrated based on the capacitor assembly configuration shown in  FIG. 6  for the production of an unbalanced Lorentz force.  FIG. 9  illustrates two oppositely charged elements of a capacitor assembly  32 ,  33  consisting of two parallel rectangular plates with a conductive discharge element  31  between them. Each plate may have a dielectric coating. The discharge element  31  is shown located at one end of the capacitor assembly, but may be located anywhere between the two plates  32  and  33 . A Helmholtz electromagnetic coil pair  15  is positioned in the required manner such that the axis of symmetry of the coil is perpendicular to the discharge conductor  31 . Similarly,  FIG. 10  illustrates a capacitor assembly  32 ,  33  consisting of two concentric cylinders with a conductive discharge element  31  between them. Each cylinder may have a dielectric coating. The discharge element  31  is shown located at one end of the capacitor assembly in such a manner as to maximize the length of element  31 . A Helmholtz electromagnetic coil pair  15  is positioned in the required manner such that the axis of symmetry of the coil is perpendicular to the discharge conductor  31 . 
         [0043]    With reference to  FIG. 11 , a preferred embodiment of the present invention is shown in cross-section. In this preferred embodiment, three capacitor assemblies consisting of charge-carrying elements  32 ,  33  each with a discharge element  31  are positioned radially about an axis of symmetry. Each capacitor assembly has an associated Helmholtz electromagnetic coil pair. Although not shown in  FIG. 11 , it is understood that each capacitor assembly has connection to a voltage source as well as charge switches  14  and discharge switches  16  as shown in  FIGS. 7A and 7B . As with the previous basic capacitor assembly embodiments, the total system forces and moments may be shown to be proportional to the product of the current durations and amplitudes in discharge conductors  31 , the total number of turns in electromagnetic coils  15 , the relative magnetic permeability of cores in coils  15 , the applied voltage across charge-carrying elements  32  and  33 , and the usual physics factors for magnetic field strengths. By stacking complete assemblies of the embodiment in  FIG. 11  along the axis of symmetry, a single power source can be used to charge all capacitors and energize all electromagnetic coils, while the total uniaxial force will be increased in proportion to the number of assemblies in the stack. 
         [0044]    With reference to  FIG. 12 , a simple design modification to the embodiment  FIG. 11  may be produced by arranging the discharge elements  31  along radials from the system axis of symmetry, and then placing the Helmholtz coils tangentially. This configuration has the advantage of being more compact than the embodiment of  FIG. 11 . 
         [0045]    With reference to  FIG. 13 , another preferred embodiment of the present invention includes a plurality of conducting coils  15  arranged about the axis of symmetry of a capacitor assembly system. The coils are arranged so that they may induce perpendicular Lorentz force components on each discharge element  31  both radially and axially with respect to the entire assembly. Appropriate variation of currents in the coils  15  result in both axial and radial translation forces as well as torques on the system, which may be used to produce controlled rotation, axial translation and lateral translation of the system. 
         [0046]    With reference to  FIGS. 14A and 14B , another unusual embodiment of the present invention is shown.  FIG. 14A  contains a capacitor assembly comprised of the usual elements  31 ,  32 , and  33 . Elements  7  show the current flow in  33  during discharge. The same current flows from element  33  downward through elements  31  and then into element  32 . The current direction in  32  is just the opposite of that in  33 . Two rectangular electromagnetic coils  25 ,  26  are positioned above and below the capacitor assembly. Current applied in  25  produces field  21  in the plane of element  33 , and a current in  26  produces field  22  in the plane of element  32 . The interaction of currents  7  in  32 ,  33  with fields  21 ,  22  produce an unbalanced vertical Lorentz force on the system.  FIG. 14B  illustrates a configuration consisting of a radial arrangement of multiple assemblies as shown in  FIG. 14A  to produce a force along the axis of symmetry of the configuration. 
         [0047]    With reference to  FIG. 15 , another interesting embodiment of the present invention is shown in partial cross-section. An electromagnetic coil  15  is wound about the entire assembly in a toroidal solenoid configuration, which when energized generates a uniform circumferential magnetic field inside the toroid. By way of illustration, four capacitor assemblies (the design may include any number) consisting of elements  31 ,  32 , and  33  are equally spaced inside the toroid, one of which is shown in the cutaway at the top of the figure. Charge switches  14  and discharge switches  16  are shown in open and closed positions respectively. When discharge switches  16  are closed after charging elements  32 ,  33 , a discharge current flows through each element  31 , which are aligned radially. The internal toroidal magnetic field interacts with the discharge current to produce a Lorentz force parallel to the axis of symmetry of the coil. 
         [0048]    With reference to  FIGS. 16A and 16B , an interesting embodiment of the present invention is shown which can utilize a low voltage for charging the capacitor assembly and then significantly increase the capacitor assembly voltage prior to discharge. The capacitor assembly consists of the usual charge-carrying elements  32 ,  33  but with each one having a dielectric surface  40 . Initially, the capacitor elements  32 ,  33  are configured such that their respective dielectrics are touching as shown in  FIG. 16A . Each element  32 ,  33  is charged in the usual manner by connecting voltage source  18  through charge switches  14 , while electromagnetic coil  15  remains unenergized and discharge switches  16  are configured as an open circuit. 
         [0049]    With reference to  FIG. 16B , once elements  32 ,  33  are charged to the appropriate potential, element  32  is displaced from element  33 , by a mechanical means not shown, thereby opening one charging switch  14  and disconnecting voltage source  18 . At the point where the displacement of element  32  is such that both displacement switches  16  are closed, so as to complete the discharge circuit as shown, then electromagnetic coil  15  is energized to create field  2 , which interacts with the discharge current in  31  to create a Lorentz force normal to the plane of the figures. The interesting fact about this embodiment is that the voltage potential between elements  32 ,  33  increases as follows due to the separation of the capacitor elements. Assume that the initial displacement of elements  32 ,  33  in  FIG. 16A  is h, which is just the total thickness of the dielectric coatings, that the voltage potential of element  18  is V 0 , and that the dielectric has a relative electric permittivity value k. If the maximum displacement of  32 ,  33  as shown in  FIG. 16B  is H, then the voltage potential between the two charge-carrying capacitor elements increases to kHV 0 /h. By way of example, if the dielectric is titanium dioxide with a k value of 100, and if the ratio H/h is 10, the voltage potential between elements  32 ,  33  at maximum displacement is 1000 times the original charging voltage V 0 . 
         [0050]    With reference to  FIG. 17 , three of the assemblies  32 ,  33 ,  40  of  FIG. 16  are arranged radially in a circular configuration. Voltage source  18  and charge switches  16  are not shown for clarity but are understood to be required for a functional device. The charge, expand, and discharge process is controlled using a design from radial aircraft engines, consisting of connecting rods  35 , crank plate  38 , and offset crank pin  37 . As pin  37  is rotated around the axis of symmetry  36  of the design, plates  32  move up and down radially. The capacitor assembly  32 ,  33 ,  40  is charged when element  32  is closest to  33 , and discharged when  32  is at the maximum distance from  33 . During discharge, the appropriate coil  15  is energized to interact with the discharge current in element  31 , to produce an axial Lorentz force component. 
         [0051]    A practical application of the present invention is illustrated in  FIG. 18 , which is a schematic of a geosynchronous orbit (GEO) space vehicle. The vehicle includes a satellite  45  as payload, attached by truss structure  44  to four solar panels  42  and two propulsion units  41 . Each propulsion unit is a large scale version of the cylindrical capacitor assembly embodiment illustrated in  FIG. 8 , with the necessary electromagnetic coils and switches to connect and disconnect the propulsion units to the solar panel electrical power system. Compared to a conventional fuel-oxidizer GEO propulsion system, the advantages of using the present invention in this manner are obvious, such as: the lack of large fuel tanks and propellant for a one-time boost to GEO, the lack of station-keeping cold gas thrusters which eventually run out of propellant, the ability to continuously change orbits, and the ability to return to low earth orbit for servicing and then return to GEO without refueling. 
         [0052]    It is to be understood that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.