Abstract:
Apparatus and methods for simulating the Earth&#39;s magnetic field. The apparatus includes a spherical structure having a rotational axis and a molten metal therewithin. A support is coupled to the spherical structure so that the spherical structure is rotatable about a rotational axis. Rotation of the spherical structure generates inertial forces in the molten metal. The apparatus may include one or more magnetometers operatively coupled to an outer surface of the spherical structure for measuring a magnetic field generated by the spherical structure.

Description:
TECHNICAL FIELD  
       [0001]    The present invention generally relates to apparatus and methods for generating a magnetic field, and more specifically, to apparatus and methods for simulating the magnetic field of the Earth. 
       BACKGROUND  
       [0002]    Earth is known to have a magnetic field, which, among other things, protects the planet&#39;s atmosphere from the effects of solar radiation. The source of Earth&#39;s magnetic field, however, is not well known. Various theories having been advanced to attempt to define and explain the source. 
         [0003]    Several unknowns remain regarding the magnetic field of planet Earth. For example, the pressure in the inner core of the earth is estimated to be about three (3) million bars. The effect of this extremely high pressure on the melting point of the materials making up the inner core or the melting point of the materials making up an outer core, which surrounds the inner core, is also unknown. Similarly, the source of heat energy that creates and maintains the temperatures of the inner and outer cores of the Earth is also unknown, especially in light of the many heat-leaking “weep holes” that are known to exist throughout the planet connecting the mantel to the crust of the planet and the approximate 4.5 billion year lifetime of the Earth. 
         [0004]    Likewise, the reasons for the observed reversal of the magnetic field of the Earth are also unknown. This reversal has been estimated to occur about every 200,000 years. Finally, the effect of high-energy particles on iron-based magnetic fields is similarly unknown. 
         [0005]    It would be desirable, therefore, to provide apparatus and methods that address one or more of the above unknowns, as well as other deficiencies in the understanding of the origin of the Earth&#39;s magnetic field. 
       SUMMARY  
       [0006]    In one embodiment, an apparatus is provided for generating a magnetic field. The apparatus includes a spherical structure having a rotational axis and including a molten metal therewithin. The molten metal may, for example, include molten iron. A support is coupled to the spherical structure at least at one point associated with the rotational axis. The spherical structure is rotatable relative to the support and about the rotational axis, with rotation of the spherical structure and a seed current or magnetic field generating the magnetic field. The apparatus may include a magnetometer operatively coupled to an outer surface of the spherical structure for measuring the magnetic field. A first drive mechanism may be operatively coupled to the spherical structure to effect rotation thereof about the rotational axis. The first drive mechanism may additionally or alternatively be configured to rotate the spherical structure at a speed of about one rotation about every ten seconds. 
         [0007]    The apparatus may include a main drive mechanism operatively coupled to the support and configured to revolve the spherical structure in an orbit about an orbital motion axis that is spaced from the spherical structure. The main drive mechanism may be configured to revolve the spherical structure to define a generally circular or elliptical path, which may have a radius of about five meters in certain specific embodiments. The main drive mechanism may be additionally or alternatively configured to revolve the spherical structure about the orbital motion axis at a speed of about one revolution per minute. 
         [0008]    The support may be coupled to two diametrically opposed points on the spherical structure, with the support including at least one thrust bearing at one of the two diametrically opposed points for supporting the spherical structure. The apparatus may include a device positioned to selectively inject energetic charged particles or an electric current into the molten metal of the outer core or into the solid inner core. The spherical structure may include an inner core and an outer core disposed about the inner core, with the inner core including at least one material selected from the group consisting of nickel, chrome, and iron steel. The outer core may contain the molten metal therein. The outer core may have a shape defined by a nickel superalloy chamber and the molten metal is contained within the chamber. 
         [0009]    The spherical structure may include a conduit fluidly communicating the chamber with an outer surface of the spherical structure. The conduit may define a longitudinal axis tilted or oriented at an angle relative to the rotational axis. The angle between the longitudinal axis and rotational axis may, for example, be about 11°. The spherical structure may include a plurality of heaters operatively coupled to the chamber for heating the molten metal contained in the chamber. 
         [0010]    The spherical structure may be scaled to be about 1/10,000,000 the size of planet Earth. The spherical structure may include an outer-most layer composed of a polycarbonate material. The spherical structure may include a chamber containing the molten metal and a solid structure disposed about the chamber, with the solid structure including at least one material, such as limestone or granite, that acts as a thermal insulator so that the outer-most layer remains relatively cool. Alternatively, the solid structure may be composed of magma basalt silicates. 
         [0011]    In another embodiment, an apparatus is provided for generating a magnetic field and includes a spherical structure having a rotational axis and having a molten metal therewithin. A support is coupled to the spherical structure at least at one point associated with the rotational axis, with the spherical structure being rotatable relative to the support and about the rotational axis. A main drive mechanism is operatively coupled to the support and is configured to rotate the spherical structure about an orbital motion axis that is spaced from the spherical structure. Rotation of the spherical structure about the rotational axis and about the orbital motion axis generates the magnetic field. 
         [0012]    In yet another embodiment, a method is provided for generating a magnetic field. The method includes pouring a molten metal such as one including molten iron, for example, into a spherical structure and rotating the spherical structure about a rotational axis thereof to thereby induce Coriolis inertia forces in the molten metal. The method may include rotating the spherical structure about an orbital motion axis that is spaced from the spherical structure. Rotating the spherical structure about the orbital motion axis may define a generally circular or elliptical path. Rotating the spherical structure about the orbital motion axis may, for example, be at a speed of about one revolution per minute. The method may include rotating the spherical structure about the rotational axis at a speed of about one rotation every ten seconds. The method may include injecting energetic charged particles or an electric current into the molten metal of the outer core or the solid inner core. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is a perspective view of an apparatus for generating a magnetic field in accordance with the an embodiment of the invention; 
           [0014]      FIG. 2  is a partial perspective view of a globe of the apparatus of  FIG. 1 , in which an interior portion is visible; 
           [0015]      FIG. 3  is a front view of the interior portion of  FIG. 2 ; 
           [0016]      FIG. 4  is a perspective view of the support and globe of the apparatus of  FIG. 1 ; 
           [0017]      FIG. 5  is a perspective view similar to  FIG. 1  showing a different embodiment of an apparatus for generating a magnetic field in accordance with an alternative embodiment of the invention; 
           [0018]      FIG. 5A  is a cross-sectional view taken generally along line  5 A- 5 A in  FIG. 5 ; and 
           [0019]      FIG. 6  is a perspective view of the globe of the apparatus in a partially assembled state with the support omitted for clarity of illustration. 
       
    
    
     DETAILED DESCRIPTION  
       [0020]    With reference to the figures and more particularly to  FIGS. 1-4 , an exemplary apparatus  10  is illustrated for generating a magnetic field  12  ( FIG. 3 ), schematically represented by dashed lines and oriented to define a North-South magnetic axis  14 . The magnitude of the magnetic field  12  may be as small as approximately 500 milligauss. Apparatus  10  includes a spherical structure in the form of a globe  16  that is sized, in this embodiment, to be about 1/10,000,000 of the size of planet Earth. Globe  16  is supported by a support  18  in the form of a carriage or cart having a cross-frame  20  with pivot arms that support the weight of the globe  16 . The support  18  is coupled to the globe  16  at least at one point along a rotational axis  22  of the globe  16 . In this exemplary embodiment, for example, the support  18  is coupled to the globe  16  at two diametrically opposed points of the globe  16 . In particular, support  18  is coupled to the globe  16  at a top point  26  coincident with an end  28   a  of a bracket  28  of the support  18 , as well as at a bottom point  32  of the globe  16 . The top and bottom points  26 ,  32  may represent the geographical poles of the globe  16 . Notably, a thrust bearing  34  is disposed adjacent bottom point  32 , and is supported by the cross-frame  20  to thereby support the weight of the globe  16 . 
         [0021]    A schematically depicted first drive mechanism  38  is operatively coupled to the globe  16  for rotating globe  16  about its rotational axis  22 , for example, at a speed of about one rotation every ten seconds. This simulates planetary rotation. For example, and without limitation, the first drive mechanism  38  could take the form of a motor and gearset mounted on the bracket  28  of support  18  and coupled to an outer surface  40  of the globe  16 . More specifically, for example, a selected motor could be one having an output less than about ½ HP and be rated for 90 volts DC, such as a motor having model number 3XA2 and commercially available from Grainger, Inc. of Lake Forest, Ill. First drive mechanism  38  may include a feature permitting adjustment of the speed of rotation of globe  16  about rotational axis  22 . For example, and without limitation, such feature may include a plurality of gears, each of which capable of being selectively coupled to a motor to adjust the resulting speed of rotation of globe  16  about rotational axis  22 . 
         [0022]    As explained in further detail below, rotation of the globe  16  about the rotational axis  22  induces inertial forces in the material confined within the globe  16 , which is believed to be capable of generating the magnetic field  12  although Applicants do not wish to be bound by theory. In this regard, the magnetic field  12  can be measured by one or more magnetometers  44  operatively coupled to the outer surface  40  of globe  16 . For example, and without limitation, the magnetic field  12  can be measured using an AlphaLab Earth Magnetometer, commercially available from AlphaLab, Inc. of Salt Lake City, Utah. More specifically, the exemplary magnetometer  44  includes a control box  48  and one or more probes  50  connected thereto and which contacts the space adjacent the globe  16 . In this regard, the term “operatively coupled to the outer surface” is intended to cover magnetometers that make physical contact with the outer surface  40  of globe  16  as well as those that simply contact the space adjacent outer surface  40  without necessarily physically contacting the outer surface  40 . 
         [0023]    With continued reference to  FIGS. 1-4 , a main drive mechanism  60  is operatively coupled to the support  18  for rotating the globe  16  in an orbit about a center  62 . In this regard, center  62  is located along an orbital motion axis  64  of the apparatus  10  and which is spaced from the globe  16 . Main drive mechanism  60  may, for example, include a motor and a transmission in the representative form of a transmission or gearset (not shown) operatively coupled to the support  18  and which in turn rotates the support  18  and the globe  16  about center  62 . Main drive mechanism  60  may be configured to rotate globe  16  at a speed of about one revolution per minute and may be additionally further configured to rotate the globe  16  about a generally circular or elliptical path  61 , which may have a radius “R” of about five (5) meters in a specific embodiment. Moreover, main drive mechanism  60  may have a feature that allows adjustment of the speed of rotation of globe  16  about center  62 . The examples provided above for the first drive mechanism  38  are similarly applicable to main drive mechanism  60 . Main drive mechanism  60  may for example be coupled to one or more of wheels  65 , such as rubber tires, of the support  18 . In this exemplary embodiment, a track  63  formed from, for example, a single-piece or multiple-piece aluminum extrusion guides the direction of movement of wheels  65  to further define rotation of globe  16  about center  62  and orbital motion axis  64 , thereby defining a plane  66  of orbital motion of globe  16 . 
         [0024]    While the exemplary embodiment of  FIGS. 1-4  includes the rotational axis  22  as being generally perpendicular to orbital plane  66  of globe  16 , those of ordinary skill in the art will readily appreciate that this is merely exemplary and, therefore, not intended to be limiting. For example, the track  63  may be modified, as shown in  FIG. 5 , by banking or inclination such that the rotation axis  22  defines a tilt angle, ε, relative to an imaginary line  67  that is perpendicular to the plane  66 . This tilt angle, ε, may, for example, be in the range of about 23 to about 24 degrees, thereby permitting simulation of the observed axial tilt or “obliquity of the ecliptic” defined by the rotational and orbital motion of the Earth. Alternatively, the coupling of the globe  16  to the support  18  may be modified so that the support  18  is tilted by the tilt angle, ε, and the track  63  is level. 
         [0025]    Rotation of the globe  16  about the rotational axis  22  and about the center  62  respectively simulates the observed rotational and orbital motion of the Earth respectively about its own axis and about the sun. As discussed in further detail below, rotation of the globe  16  about rotational axis  22  and orbital motion axis  64  is believed to generate magnetic field  12  that extends about the globe  16 . Moreover, a charged particle delivery device  80 , such as an electron gun, of the apparatus  10  may be positioned to selectively inject energetic charged particles into an interior of the globe  16  to cooperate in the generation of the magnetic field  12 . 
         [0026]    With particular reference to  FIGS. 2 and 3 , the structure and materials defining globe  16  cooperate with motion thereof, as described above, to generate magnetic field  12 , although the Applicants do not wish to be bound by theory. To this end, the overall exterior shape of globe  16  is defined by two complementary hemispherical shells  100  and  102  (shell  102  shown in phantom) that are coupled to one another, for example via fasteners such as bolts, to thereby define the spherical shape of globe  16 . In this regard, the hemispherical shells  100 ,  102  of this exemplary embodiment define an outer layer or crust  104  of globe  16 . The hemispherical shells  100 ,  102 , which define the largest sphere of the globe  16  when joined together, are composed of a cured polycarbonate resin thermoplastic with a thickness of, for example, about 25 mm. In one embodiment, the cured polycarbonate resin thermoplastic may be LEXAN®. An inner core  110 , which represents the smallest sphere of globe  16 , is disposed at the center of the globe  16  and is made of a solid material. In this embodiment, inner core  110  includes cast steel containing nickel, chrome, and iron. Those of ordinary skill in the art will readily appreciate that inner core  110  may be alternatively made of other materials. For example, inner core  110  may be made of a material including any or all of the materials discussed above or other materials, so long as the selection of materials permits the inner core  110  to remain in a solid state. 
         [0027]    An outer core  120  is disposed within globe  16  and about inner core  110 . Outer core  120  includes a pair of opposed hemispherical shells  122  (only one shown) united to form the outer core  120 . The shells  122  may be composed of an austenitic nickel-based superalloy, such as Inconel®, although the outer core  120  may alternatively be composed of other types of materials. Outer core  120 , which defines a sphere characterized by a radius intermediate of the radius of the inner core  110  and the crust  104 , defines an internal chamber  130  that confines or contains a molten metal  132  (depicted in the drawings as a pattern of dots for illustrative purposes). 
         [0028]    In one embodiment, the molten metal  132  is composed of gray iron heated to a temperature adequate to liquefy the solid material and place it into a molten state. It is contemplated, however, that molten metal  132  may include other materials in addition to or as an alternative to the molten iron of this exemplary embodiment. Gray iron or grey iron, which was the original “cast iron”, is an alloy of carbon, silicon, and iron, containing from 1.7 to 4.5% C and 1 to 3% Si. Moreover, the exemplary molten metal  132  of this embodiment has eutectic phase change and melting points in the range of about 1160° C. to about 1200° C. 
         [0029]    Gray iron is characterized by a Curie point of about 770° C. The Curie point of a ferromagnetic material like gray iron is the temperature above which it loses its characteristic ferromagnetic ability. At temperatures below the Curie point, the magnetic moments are partially aligned within magnetic domains in ferromagnetic materials. As the temperature is increased towards the Curie point, the alignment (magnetization) within each domain decreases. Above the Curie point, the material is purely paramagnetic and there are no magnetized domains of aligned moments. Some metals, such as sodium, are paramagnetic, and lack a Curie point or magnetic polarity in any form. When molten, gray iron is purely paramagnetic as the Curie point is far exceeded. Gray iron has a high 18,000 gauss saturation (B) or residual flux density, and a high 6,500-9,000 gauss retentivity (H) magnetizing capacity. 
         [0030]    In the representative embodiment, gray iron is relatively non-reactive metal, in comparison to more reactive metals like sodium. Gray iron has a relatively high specific gravity of about 7.5, in comparison with less dense metals like sodium that is characterized by a specific gravity of only about 0.93. The comparatively high specific gravity (density) of gray iron is attractive because it is believed to promote the simulation of the inertial forces. The comparatively high melting point of gray iron is believed to be attractive for promoting convective heat transfer, which may be difficult to promote with metals characterized by a lower melting point, such as sodium. The existence of a eutectic phase change also enhances the attractiveness of gray iron over other alternative metals that lack a eutectic phase change, such as sodium. 
         [0031]    Notably, one or both of the rotational motion of globe  16  about rotational axis  22  and orbital motion axis  64  causes movement of the molten metal  132  within outer core  120 . More specifically, movement of the molten metal  132  generates Coriolis inertial forces in the molten metal  132 . Although not wishing to be bound by theory, the Coriolis inertial forces in the molten metal  132  are believed to cooperate with naturally occurring convection currents within the chamber  130  to form electric currents in rolls aligned along the magnetic axis  14 , thereby generating the magnetic field  12 , although Applicants do not wish to be bound by theory. Convection currents may occur as a result of the temperature gradients existing across chamber  130  and within the molten metal  132 . When a conducting fluid, such as molten metal  132 , flows across the magnetic field  12 , additional electric currents are induced, which, in turn, continue to generate magnetic field  12  in a self-perpetuating mechanism, although Applicants do not wish to be bound by theory. 
         [0032]    In use, the apparatus  10  will be monitored for the presence of the magnetic field  12  with the globe  16  held static and, if the magnetic field  12  is not measurable, the globe  16  will be rotated to introduce the inertial forces into the molten metal  132 . If the magnetic field  12  is still not measurable, charged particles or an electrical current may be introduced into the molten metal  132  inside the globe  16 , as described below 
         [0033]    With continued particular reference to  FIGS. 2 and 3 , globe  16  includes an annular spherical shell in the form of a mantle  146  that surrounds the outer core  120  and fills the volume defined between outer layer  104  and outer core  120 . In one embodiment, mantle  146  is constructed from segments composed of a cast mixture of limestone and granite. It is contemplated, however, that mantle  146  may instead be made from other materials instead of, or in addition to, the limestone and granite of the representative embodiment. For example, mantle  146  may be made of a material including only one of limestone and granite. Alternatively, the mantle  146  may be composed of magma basalt silicates or another type of glass with a suitable composition to operate as a thermal insulator. Moreover, the mantle  146  of the representative embodiment is defined by twelve segments having complementary shapes such that, when coupled, may define the overall hollow-spherical shape of mantle  146 . Those of ordinary skill in the art will readily appreciate that mantle  146 , which functions as a thermal insulator, may be instead made of a single segment or a different number of segments. 
         [0034]    Globe  16  includes features that permit the introduction of the molten metal  132  by a simple pouring process. In particular, a conduit  150  provides a fluid communication path between the outer surface  40  of globe  16  and the chamber  130  of outer core  120 . More specifically, a first end  152  of conduit  150  is coupled with one of the shells  122  defining outer core  120  to thereby provide access to chamber  130 . A second end  154  of conduit  150  is in the form of a funnel to facilitate pouring and directing of the molten metal  132  thereinto. Notably, conduit  150  may further facilitate the injection of energetic charged particles, such as electrons, into the chamber  130 , which cooperates to further facilitate generation of magnetic field  12 , although again Applicants do not wish to be bound by theory. Conduit  150  extends along the magnetic axis  14  that, in this illustrative embodiment, is oriented at an angle of about 11 degrees relative to the rotational axis  22 . 
         [0035]    Other features of globe  16  provide structural integrity thereto. For example, in this embodiment, a plurality of structural supporting hollow rods  166  extend from the inner core  110 , through the outer core  120  and are coupled to the outer layer  104  of globe  16  to support the inner core  110  and outer core  120 . Those of ordinary skill in the art will appreciate that other types of structural features may be present in addition or as an alternative to support rods  166 . Notably, the hollowness of support rods  166  may permit injection of charged particles from device  80  into the chamber  130  containing the molten metal  132 . Injection of charged particles into chamber  130  polarizes the domains of the molten metal  132  to thereby further facilitate the generation of magnetic field  12 , although again Applicants do not wish to be bound by theory. The hollow tubes defined by support rods  166  may also permit the introduction of electric wires (not shown) that allow the introduction of an electric current into the inner core  110  and/or outer core  120  that would act as a seed current for the generated magnetic field  12 . Moreover, the hollowness of support rods  166  may also permit the introduction of one or more thermocouples  168  therethrough (schematically shown as lines) that facilitate measurement of the temperature within chamber  130 . The support rods  166  may be formed from a high temperature material, such as a nickel-based superalloy like Inconel®. 
         [0036]    With continued particular reference to  FIGS. 2 and 3 , one or more electrical heaters  188  are operatively coupled to outer core  120 . Heaters  188 , such as silicon carbide rod-type heating elements, permit preheating the inside of the device and maintenance of a desired temperature of the molten metal  132  within chamber  130 , for example, at a temperature of about 1300° C. In this regard, heaters  188  may be operatively coupled to a control system (not shown) that receives temperature data as positive feedback from the thermocouples  168  and selectively energizes heaters  188  in ways known in the art. Heaters  188  include terminal blocks in the form caps  189  that are accessible at the outer surface  40  of the globe  16  to permit coupling of wires  190  to the heaters  188  for transmitting electrical power to the heaters  188  from an external power source (not shown). In this illustrative embodiment, globe  16  has 24 heaters  188 , more specifically two in each of the twelve segments defining the mantle  146 . The tips of the heaters  188  are spaced by respective gaps from the outer surface of the inner core  110 . 
         [0037]    With reference to  FIGS. 5 and 5A , in which like reference numerals refer to like features in  FIGS. 1-4 , an apparatus  10   a  includes a track  63   a  similar in most respects to track  63 , but which is inclined or banked to permit rotation of the globe  16  with the axis  22  oriented at an angle, ε, relative to imaginary line  67 . 
         [0038]    With reference to  FIGS. 1-4  and  6 , the apparatus  10  is assembled by initially mounting the lower hollow hemispherical shell  102  of the thin outer crust  104  to the support  18 . The lower segments, such as the representative segments  200 ,  202 , of the mantle  146  are placed inside the hemispherical shell  102 , which holds the segments  200 ,  202  in place. The lower shell  122  is placed to rest on the segments  200 ,  202 , as shown in  FIG. 6 . Amounts of a filler material (not shown) are applied to fill the seams between adjacent segments of the mantle  146 , which functions to reduce heat loss through the seams. The segments  200 ,  202  of the mantle  146 , as well as the other segments that are not visible in  FIG. 6 , support the mass of the outer core  120 . The upper hemispherical opposed shell  122  of the outer core  120  is then joined to complete the spherical outer core  120 . The support rods  166  penetrate through openings in the form of slots along the location where the opposed hemispherical shells  122  of the outer core  120  are joined. The upper segments of the mantle  146  are then placed into position. The heaters  188  extend into the annulus define between the upper and lower hemispheres of the mantle  146 . The completed mantle  146  now rests inside the lower hemisphere  102  of the outer crust  104 . The upper hemisphere  100  of the outer crust  104  is then lowered into position to complete the spherical outer crust  108 . After the thermocouples  168  are inserted, the bolts are clamped to secure the globe  16 . 
         [0039]    While the invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features described herein may be utilized alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.