WO2013110960A1

WO2013110960A1 - Apparatus for generating a propulsive force using superconductors

Info

Publication number: WO2013110960A1
Application number: PCT/GR2013/000007
Authority: WO
Inventors: A. Athanassios NASSIKAS
Original assignee: Nassikas A Athanassios
Priority date: 2012-01-23
Filing date: 2013-01-22
Publication date: 2013-08-01
Also published as: GR20120100051A

Abstract

A means for the generation of propulsive force and an apparatus (1) for implementing the means comprising a solenoid (3), such as a superconductive electromagnet, filling, partially or wholly, the convergent portion of a superconductive tapered tube (2) of optimal length, whose solid parts are made of a superconductor with high magnetic field trapping ability, such as the type II superconductor Y--Ba--Cu--0, and within which a propulsive force is developed due to the Meissner effect. The propulsive force, which is directed toward the tapered tube's converging end, may be used for the propulsion or operation of any machine, motor, or vehicle. One arrangement employed for the creation of a strong magnetic field comprises, a solenoid placed at the wide end of said tapered tube, whilst another arrangement comprises a pair of superconducting solenoids (3, 4) located at the ends of said tapered tube (2), whilst yet another arrangement comprises a superconductive solenoid (5) located in the convergent region (2b) of said tapered tube and powered by an AC or DC power source (6).

Description

APPARATUS FOR GENERATING A PROPULSIVE FORCE

USING SUPERCONDUCTORS

Nassikas, Athanassios A.

Priority Statement

The present application hereby claims priority on Greek patent application number GR 20120100051 filed January 23, 2012, which is hereby incorporated herein by reference.

Field of the Invention

The present invention relates to superconducting magnetic propulsion systems. The present invention relates to the magnetic field exclusion below a critical temperature in a superconductor, i. e., the Meissner effect.

The present invention relates to high critical temperature type II superconductor

Background of the Invention

There is a history of magnetic levitation and magnetic propulsion systems, for example: H. Johnson, 1995. "Magnetic propulsion system". U.S. Pat. No. 5,402,021 and M. Brady, 2004. "Permanent magnet machine (Perendev)". WO 2006/045333. The inventions of Johnson and Brady use non-superconductors.

Y. Kambe, 1996. Yoshitaka (JP)-TOYOTA MOTOR CO LTD (JP). EP0748033. The invention of Kambe uses a magnetic field source and superconducting material.

G. Lanzara, 1990. "Magnetically levitated vehicle with superconducting mirror sheets interacting with guideway magnetic fields." U.S. Pat. No. 4,979,445. The magnetic levitation invention of Lanzara uses a magnetic field source and a superconducting material exhibiting the Meissner effect; however, unlike the present invention, its magnetic field source is not secured to the superconductor.

A previous Greek application GR-20090100276 disclosed an apparatus for generating a propulsive force that comprises a superconductive tapered tube and a magnet field generating source such as a solenoid mounted at the narrower end of said tapered tube. The present invention differs from this previous embodiment in that it proposes a differing placement of the magnet field generating source in relation to the tapered tube. Rather than placing said field source at the narrower end of said tapered tube, the present invention finds, it advantageous to place said field source entirely within said tapered tube at the wider end of said tube, or within the converging throat of said tapered tube, or to employ two magnetic field sources one placed at either end of said tapered tube entirely within said tapered tube. The advantages of these field source placements and embodiments are that said apparatus generates a stronger propulsive force as is explained below.

Summary of the Invention

The object of the present invention is to provide an electromagnetically developed propulsive thrust from a hollow, conically-shaped superconductor, i.e., a tapered tube, driven by a magnetic field generated by a superconducting solenoid, or similar magnetic field source. A magnetic field generated by an electrically driven magnetic field source is applied to a preferably high temperature superconductor having the shape of a tapered tube. After the magnetic field is established, the tapered tube superconductor is cryogenically cooled to and below the critical temperature, forcing the magnetic field mostly out of the superconducting tapered tube. Experimental verification is provided below.

The system comprising the superconductor tapered tube and superconducting solenoid may be cooled below its critical temperature by contact with a cryogenic material. For example, said system may be cooled by immersion in a cryogenic fluid coolant like liquid helium or liquid nitrogen, by forced circulation of said coolant through the system, or by being placed in contact with a solid coolant such as cryogenic solid neon. Furthermore, said system may be cooled by means of a mechanical heat engine, such as a Sterling engine, or by a solid state Peltier thermoelectric cooling device. Superconductors normally function as magnetic field shields, but they lose their shielding properties when the magnetic field becomes very strong. This is especially problematic with type I superconductors. Type II superconductors are able to maintain their superconducting state even when exposed to much higher magnetic field intensities, but, as described above, they do not function as perfect magnetic field shields. When such a superconductor is below its critical temperature T_c and subject to critical magnetic field strengths in the range between Hci and H_C2, the Meissner effect is less perfect, there being some magnetic field leakage through the type II superconductor. Nevertheless, the proposed invention works adequately to produce propulsion even if the shield is fabricated from a type II superconductor.

The present invention is not predicated on a hydro dynamical interaction between the surrounding fluid and the superconductor solid part. The cryogenic fluid is merely one illustrative example of a cooling medium that is necessary in both embodiments for the superconductor solid part to maintain its superconductive properties and therefore, through the Meissner effect, to repulsively interact with the applied external magnetic field in order to produce a propulsive force. Moreover, it is emphasized that equation (5) presented below that expresses the force being generated in the preferred embodiment of the invention, is not an equation of hydrodynamics involving any parameters of a working fluid, but an equation derived from the classical theory of magnetic fields.

One principal feature of the present invention is that said superconductor which functions as a magnetic field shield has the form of a tapered tube that surrounds and constrains the lines of magnetic flux produced by said magnetic field source, preventing their outward penetration and causing them to converge within said tapered tube magnetic field shield enclosure and thereby resulting in a pressure against said shield's inner surface. The magnetic field pressure acting on said shield acts as a propulsive thrust in the direction of the shield's narrower end, hence, in the direction of field line convergence.

The ability to magnetically induce a thrust on a superconductor may appear paradoxical, however, this is comparable to the apparent paradoxical effect of the Faraday disc generator where the magnetic field produced by a rotating magnet electro dynamically induces currents in a copper disc cemented to the magnet (One-piece Faraday generator: A paradoxical experiment from 1851. Crooks, et al. July 1978 Am. J. Phys., vol. 46, no. 7, pp. 729-731). In both cases the apparent paradox is resolved if the magnetic field is understood to be deployed in space in a manner independent of its field source. For example, Michael Faraday, the originator of the law of electromagnetic induction (F = qv X B), in 1831 had observed that the magnetic field created by a magnet was not rigidly attached to its source magnet, but that it behaved independently of its magnet. He observed this in experiments he conducted with a copper disc cemented to a rotating cylindrical magnet whose axis of rotation was aligned with its axis of magnetization. In paragraphs 256, 257, and 258 of his diary, dated December 26, 1831, he describes that when he connected a galvanometer between the center and edge of the rotating copper disc, he observed a voltage whose polarity correlated with the direction of rotation and that was registered even when the magnet instead remained still while the disc rotated {Faraday's Diary, Michael Faraday, Thomas Martin (editor), Royal Inst. Great

Britain, 2008, vol. I, pp. 402-403). He comments: "A rotary and a stationary magnet cause the same effect." He also found that keeping the disc stationary while revolving the magnet produced no galvanometer voltage. This leads to the conclusion that the magnetic field of a revolving magnet remains stationary in space. This is also consistent with convention in electromagnetic theory which considers that electromagnetic waves radiated from an antenna propagate forward with no rigid attachment to the emitting antenna, while exerting back only a small reaction force called the radiation reaction.

In a similar fashion, the magnetic field generated by a solenoid in the present invention may be considered to establish itself in space and to exert a pressure on the adjacent tapered tube superconductor shield while at the same time having no rigid attachment to said solenoid that generates said field. The same principle can explain the levitation of a maglev train by a magnetic field produced by a solenoid situated on the train track and inducing a repulsive magnetic field in an overlying horizontal superconductor situated on the train thereby raising the train above its track. Or alternatively, the same principle can explain the transverse thrust that a solenoid's magnetic field induces on a maglev train that employs tiltable

superconductor plates, as described in the patent by Lanzara (U.S. Pat. No. 4,979,445). In the case of the Lanzara maglev apparatus where the superconductor plates are tilted relative to the magnetic field axis, the magnetic lines of flux adjacent to the superconductor shield surface produce a thrust according to the Meissner effect and this thrust has a component oriented either toward the front of the train or toward its rear depending on the tilt of the shield surface. So regardless of whether the magnetic field source is fixed on the ground and develops a motion relative to the repelling superconductor shield, as in the maglev apparatus, or whether said magnetic field source is attached to said superconductor shield, as in the case of the present invention, the repulsion between the magnetic lines of flux adjacent to the shield surface and the pinned magnetic fields created by supercurrents in the superconductor shield occurs in a similar manner in both cases. This thrust effect in both cases is a phenomenon peculiar to the use of superconductors and their ability through the Meissner effect to create magnetic lines of flux opposing the external magnetic field.

The present invention does not claim a mechanism contravening the law of energy conservation. First, to achieve its superconducting state for a given magnetic field intensity Hci, the system must cool below its minimum critical temperature T_cl. Maintaining this minimum critical temperature requires a continual expenditure of energy necessitating an energy supply. If forced circulation of a cryogenic liquid is employed, an additional energy supply is necessary to sustain this circulation. Furthermore, an input of energy is necessary when a superconductor solenoid is employed as the means for applying a magnetic field. Nevertheless, it is reasonable to inquire where the device herein disclosed acquires its energy for propulsion. This question is equivalent to asking where a maglev train superconductor acquires the energy that levitates it above its track. Consider the ideal case of a maglev train which rests on a rail that contains underlying embedded permanent magnets each of whose field axes points upward towards overlying horizontally disposed high-temperature superconductor plates attached to the bottom of the train. Imagine that initially these superconductor plates are above their critical temperature and that the train rests firmly on its rails, the magnetic field from each magnet passing through its respective overlying superconductor. Now, a cryogenic liquid is added to insulated containers that surround each plate to cool them below their critical temperature. As the plates become superconducting, they develop supercurrents which produce pinned magnetic fields having a polarity opposed to the magnetic fields from the underlying magnets and they repulsively expel those fields. The mutual repulsion of these opposed fields produces an unbalanced force which levitates the train, a process that requires energy. The energy required for levitating each plate amounts to the weight resting on that plate, multiplied by the levitated distance which would be approximately 1.5 centimeters.

Related to this, there is the question of how the pinned fields in the superconductor plates sustain themselves to continue this repulsion as they keep the train levitated. What centripetal force acts to keep Cooper pair electr^ons indefinitely circling as supercurrents and forming their pinned fields when at the same time these fields are being forcefully opposed by the external magnetic field that these fields are actively expelling? These supercurrents cannot be circling due to the effect of the external magnetic field, since the generated pinned fields for the most part expel this external field from the superconductor. Furthermore it is unlikely that these supercurrents or their pinned fields would be drawing the required energy for levitating the train from this external magnetic field because the pinned fields are opposing these magnetic fields. It is also unlikely that in creating their pinned fields that the supercurrents draw energy from the superconductor's environment, that is, from the surrounding cryogen cooling bath. This would go against the conventional understanding that heat flows out of the superconductor into its cooling bath as it cools below its critical temperature, and not vice versa.

One possible alternative is that this energy comes from the quantum field itself. This is a reasonable possibility since the phenomenon of superconductivity is generally considered to be a quantum phenomenon. Quantum field theory, as conventionally taught, holds that the field of any particle, including the Cooper pair electrons in superconductor supercurrents, are nonlocalized, hence that the fields of such Cooper pair electrons as well as the fields of the particles forming the substance of the superconductor are intertwined with the quantum vacuum which extends everywhere through space and which is theorized to comprise a vast store of energy. So, one explanation would be that when supercurrents create and sustain themselves and their pinned magnetic fields which levitate the train, they are drawing energy from this omnipresent reservoir. The same reasoning discussed in regard to the maglev train example also pertains to the present invention which similarly involves a superconductor form generating pinned fields which repel the externally applied magnetic field.

Regardless of the question of where the pinned fields acquire their energy, in the case of the presently disclosed propulsion device, the thrust effect on said superconducting tapered tube may be seen to be predicted by the accepted laws of classical magnetism, as described below. Brief Description of the Drawings

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the

accompanying drawings, in which: FIG. 1 is a cross-sectional view of a device capable of developing a propulsive thrust which consists of a superconducting tapered tube with a magnetic field source superconducting solenoid located at its wide end producing a magnetic field that acts on the superconducting tapered tube to create a thrust.

FIG. 2 displays a cross-sectional view of said thrust-producing device similar to that shown in FIG. 1 that utilizes two magnetic field source superconducting solenoids, one at each end of a superconducting tapered tube.

FIG. 3 displays a cross-sectional view of said thrust-producing device that utilizes a conically shaped superconducting solenoid magnetic field source placed within the tapering throat of a superconducting tapered tube. FIG. 4 (prior art) is a cross-sectional view of a device capable of developing a propulsive thrust described in application No. GR-20090100276 comprising a superconductive tapered tube with a magnet mounted at its narrow end.

FIG. 5 illustrates how trapped flux in an YBCO superconductor varies with the

superconductor's temperature when excited with a magnetic field flux ranging from 6 to 8 Tesla.

FIG. 6 illustrates an experiment carried out by A. Nassikas which shows the type II superconducting tapered tube responding to a Meissner-effect-mediated magnetic field while suspended on a Teflon line in a pendulum manner and immersed in a liquid nitrogen bath.

Detailed Description of a Best Mode The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is merely made for the purpose of describing the general principles of the invention. One embodiment of the present invention comprises a magnetic propulsion device (1) consisting of a superconductive tapered tube (2), preferably made from a type II

superconductor, and a magnetic field source solenoid of cylindrical shape (3) fixed to the wide end of the tapered tube as shown in FIG. 1 such that the primary magnetic field axis of said field source is approximately coaxial with the tapered tube's axis of symmetry. Said solenoid is positioned within a non-tapering end section (2b) of said tapered tube, said non- tapering portion having a cylindrical form with constant cross section. Said tapered tube would have a thickness sufficient to shield most of the external magnetic flux impinging upon it.

A second embodiment of the present invention comprises a magnetic propulsion device (1) consisting of a superconductive tapered tube (2) and two magnetic field source solenoids of cylindrical shape (3) and (4) fixed to either end of the tapered tube as shown in FIG. 2 such that the primary magnetic field axis of each magnetic field source, or solenoid, is

approximately coaxial with the tapered tube's axis of symmetry. Each such solenoid is positioned within non-tapering end sections (2b) and (2b¹) of said tapered tube, each having a cylindrical form with constant cross section.

A third embodiment of the present invention, as shown in FIG. 3, comprises a magnetic propulsion device (1) consisting of a superconductive tapered tube (2) and a magnetic field source solenoid of conical shape (5) which is fixedly attached to said tapered tube within the tapered portion (2a) of said tapered tube such that the primary magnetic field axis of said field source is approximately coaxial with the tapered tube's axis of symmetry. Said solenoid may be powered either from a source of direct or alternating current (6).

The solenoids employed in said embodiments may be either normal solenoids, solenoids with magnetizable cores, or superconductive solenoids. Said solenoids may be wound either as bobbins or as a series of adjacent, coaxial pancake coils. In the third embodiment, the diameter of said pancake coils would progressively decrease to conform to the converging shape of the tapered tube throat. In all embodiments an energy supply of either direct or alternating current is required to maintain the current in said solenoids against resistive losses if it is a normal solenoid, or to provide an energizing power source in the case where said solenoid is a superconducting solenoid. Although an energy supply for the solenoids is not depicted in FIGS. 1 and 2, it should nevertheless be understood that one is present. Examples of type II superconductors, also referred to as high-temperature superconductors, include cuprate ceramic materials such as Y— Ba~Cu— O (YBCO) or Sm— Ba~Cu~0 which more generally are called REBCO (Rare Earth-Ba₂Cu₃0,._x) superconductors. The

superconductor Sm--Ba— Cu— O is able to trap magnetic fields to produce pinned fields as large as 10 Tesla (Melt-processed Sm— Ba~Cu~0 superconductors trapping strong magnetic field H. Ikuta et al. 1998 Supercond. Sci. Technol. 11 1345-1347). Bulk YBCO

superconductors have been shown to trap magnetic fields as high as 17 Tesla (High temperature superconductor bulk magnets that can trap magnetic fields of over 17 tesla at 29 K. M. Tomita & M. Murakami 2003 Nature, vol. 421 , pp. 517-520). Melt-texturing of a REBCO type II superconductor during its fabrication improves its ability to trap magnetic fields even at liquid nitrogen temperatures (Polycrystalline HTS material for bearings and electric power devices. F. N. Werfel, et al. 2001 Physica C, vol. 357-360, pp. 843-851.) (Superconductor bearings, flywheels and transportation. F. N. Werfel, et al. 2012 Supercond. Sci. Technol., vol. 25, 014007, 16 pp.).

The following presents one way of understanding the field-propulsion effect that is the subject of the present invention. Referring by example to FIG. 1, the magnetic field originating from solenoid (3) of the present invention may be considered to establish itself in the space surrounding said solenoid. Furthermore, when this generated field encounters a magnetic barrier comprised of a superconducting tapered tube shield (2) that exhibits the Meissner effect, the vortex current which this external field induces within said tapered tube will generate a pinned field throughout said tapered tube shield that opposes and repels this external field. As a result, said external field will impart a repulsive force to said tapered tube shield. This external generated magnetic field will exert said repulsive force on all sides of said tapered tube shield, but in varying amounts due to the variation in magnetic field intensity present over differing sectors of the shield's surface. As may be seen in FIG. 1, the magnetic field contacting the inner surface of said shield, within the tapered tube's throat, will have a greater strength than that contacting the outer surface of said shield. This is because within the tapered tube throat the magnetic lines of force have a close proximity to the magnetic field source and are forced to converge to a high intensity by the confinement within the tapered tube throat, whereas in the vicinity of the more distal outer surface of the shield, the magnetic lines of force are deployed through a much larger volume of space as they arc between the solenoid's two poles and hence the outer surface of the superconducting tapered tube shield is exposed to a much weaker field intensity. As a result of this difference in field intensity, unbalanced forces will develop on the superconducting shield. That is, the incremental magnetic force dF, pushing outward against an incremental surface ds of the inner surface of said shield produces an incremental magnetic pressure (dF,/ds) which is greater than the incremental magnetic pressure (dF₂/ds) pushing inward against the outer surface of said tapered tube shield (FIG. 1); i.e., dFi » dF₂. The resultant force (or pressure) vector components oriented perpendicular to the tapered tube's axis of symmetry will cancel out one another. But the force (or pressure) vector resultant directed parallel to the tapered tube's axis of symmetry will be aimed in the direction of tapered tube convergence and will act to propel the tapered tube in this convergence direction. This result is obtained regardless of the cross-sectional geometry of the tapered tube, i.e., regardless as to whether the tapered tube has a circular, elliptical, rectangular, or polygonal cross section.

In general, the inner-directed forces (dF₂) acting on the outer surface of the tapered tube will be far weaker than the outer-directed forces (dF^ acting on the inner surface of the tapered tube, hence acting within the throat of the tapered tube. So to a first approximation, the forces acting on the outer surface of the tapered tube may be neglected and we may calculate the propulsion force acting on the tapered tube solely in terms of the forces acting on said tube within its throat.

Numerical Calculation

To make such a calculation we begin on the basis of the classical theory of the magnetic field. The equation for the force exerted on a closed surface S is given as:

F = -g[H(n - B) + B(n - H) - n(H - B)]dS (1)

2 s where H is the magnetic field intensity, B is the flux density, and n is the unit vector perpendicular to surface S under consideration, which faces outwardly from this surface.

In expressing the force exerted on a superconducting magnetic field shield, we take η·Β=0 and η·Η=0 which sets the first two terms in equation (1) to zero, giving: F =— ^n(H · B)dS (2)

2 '_S

This means that the force exerted on a surface element dS will equal:

dF = ~n(H - B)dS (3)

Consequently, a magnetic field with properties H and B existing in the vicinity of a magnetic field shield element dS, with μ₀ the magnetic permeability and n = 1 , will create a pressure p on this element, such that:

p = dF/dS = ^(H - B) = -^-B² (4)

2 2μ_ϋ

This indicates that by means of a solenoid and a magnetic field shield, configured in the above stated manner, that it is possible to create a variety of magnetic propulsion engines, the propulsive force of which is given by pressure equation (4).

It is important to note that the London equations are accepted as being valid in the description of phenomena taking place within the superconducting material where the pinning forces and trapped fields related to the present invention are being created, while far from this region Maxwell's equations dominate as the valid descriptor. However we do know that Eq. (1) of classical magnetism can be applied to the present invention because the surface S for integrating Eq. (1) may be chosen to lie outside of any material component, hence far from the superconductor domain. So Eq. (1) provides an adequate theoretical basis for

understanding the operation of said invention. More specifically, in the present invention, Eq. (1) applies precisely for boundary conditions with μ = 0, corresponding to type I superconductors, hence to materials that are known to exist and can be approximately extended to type II superconductors, which have μ very small or a μ that is anisotropic.

On the basis of the classical theory of magnetism, the magnetic force exerted on a closed surface S is given by Eq. (1). Applying Eq. (1) for the calculation of the force on the tapered tube under discussion we have:

where, Β_α and B_p are the magnetic flux densities at respectively the smaller and the larger sections shown in FIG. 1, where Φ = A„ x Β_α = Α_β x B_p is the magnetic flux, and A_a and A_p are the cross sectional areas of those respective sections. This equation indicates that the thrust is towards the direction of convergence, that is towards the smaller section a, regardless of the applied magnetic field polarity. As a result, the magnetic propulsion device will produce a thrust irrespective of whether its solenoids are energized with DC or AC power.

The above equation represents the interaction between the magnetic field (B) and the superconducting shield (2). In reality near the magnetic field shield, the situation is more complicated, involving quantum phenomena related to Cooper pair flux trapping. It is important to note that Eq. (5) above indicates that the propulsive force developed on the shield scale's approximately according to B², the square of the magnetic flux density of the solenoid (3), and according to the difference in cross-sectional area A. The approximation symbol "~" is used for two reasons. First, this equation assumes that the vector B is perpendicular and constant at all points of the cross sectional areas A_a and A_p, which is only approximately valid. Second, Eq. (5), in its accurate form, is valid only for the case where material (1) is a type I superconductor, which is of a type that does not permit the passage of any magnetic field. Thus, by designating its approximate version, the formula, Eq. (5), pertains also to type II superconductors which have some magnetic field leakage. A numerical calculation of the propulsion force F may be made with the aid of the Quick Field Finite Element Systems program [Quick Field, Finite Element Systems, User's Guide Version 5.3 -Terra Analysis Ltd. (2005)]. This program is used for calculating magnetostatic forces wherever they appear in electromagnetic machines. This calculation is precise for superconductors that have boundary conditions with μ = 0 (type I superconductors), and can be approximately extended to type II superconductors, which have μ very small. Such calculations give a better approximation when they take into account the anisotropic behavior of μ in type II superconductors. The previous embodiment of the present invention for generating a propulsive force, as disclosed in GR-20090100276, is shown in Fig. 4. Said magnetic propulsion device (1) comprises a superconductive tapered tube (2) extending from a wide inlet end (β) to a narrow outlet end (a), and which includes a conically shaped convergent portion (2a) and a cylindrically shaped portion with a constant cross section (2b¹) located at the narrow end (a) of said tapered tube (2), and includes a magnetic field source (3) fixedly attached near the narrow end of said tapered tube (2) and extending partially within the non-tapering portion of said tube (2b'). The magnetic field created by said magnetic field source produces a pressure on the superconductive tapered tube (2) as expressed by equation (4) above. Moreover in this previous 2009 disclosure, as in the presently disclosed embodiment, unbalanced forces dF, and dF, are produced on the inside and outside of said tapered tube such that dFj » dF₂, which results in a net propulsion of the device.

However, by placing the magnet field source entirely within said tapered tube at the wide end of said tube, as is done in the present invention (FIG. 1), a much greater flux density B is created within said tapered tube, and this dramatically increases the propulsive force which the device develops. In addition, by placing magnet field sources at both the wide end and narrow end of said tapered tube, as shown in FIG. 2, or by placing a conical magnetic field source entirely within the tapered portion of said tapered tube, as shown in FIG. 3, again a much greater flux density B is produced within the tapered tube as compared with that created by the previous 2009 disclosure. Consequently, all of the embodiments disclosed herein produce a dramatically greater propulsive thrust as compared with that produced in the previous disclosure. The alternative placement of a solenoid magnetic field generating source disclosed in the present invention increases the magnetic flux density within the superconducting tapered tube for several reasons which may be understood as follows. First, based on a knowledge of the closed integral form of Ampere's law, we know that

in out where N signifies the total number of turns, I signifies the current passing through the solenoid, and where [J] Heft , the closed line integral of the magnetic field intensity, is equal to

J HC¾ the integral of the magnetic field intensity inside of the solenoid, plus J Heft the in out integral of the magnetic field intensity outside of the solenoid. The "in" term which represents the field inside the solenoid, integrates to H_mL where H_m is the average field intensity inside the solenoid, and L is the length of the solenoid. The field outside the solenoid may then be expressed as:

J^* Hi/l = NI - H_mL . (7)

Out A large diameter solenoid spanning the wide end of the tapered tube will have a small H_m in comparison to a small diameter solenoid spanning the narrow end of the tapered tube. This is because H_m = Φ/μ₀Α, where Φ is the magnetic flux of the solenoid and A is its cross-sectional area. So, if for example the wide end of the tapered tube has an area three times larger than the narrow end, the magnetic intensity inside a solenoid spanning the wide end of the tube will be one-third of that of the magnetic intensity produced inside a solenoid spanning the narrow end of the tube, in the case where each solenoid produces the same magnetic flux. Consequently, referring to Eq. (7), we see that for a solenoid at the wide end the term H_mL will be much smaller and the external magnetic field intensity will be

much larger than is the case for a magnet at the narrow end of the tapered tube. It is this external field that is present within the throat of the tapered tube that is significant for producing said propulsive force since a more intense magnetic field is able to induce stronger repulsive pinned fields in the superconductor. As mentioned earlier, said propulsive force varies as B². Hence if, for example, the average magnetic flux density B is three times larger, the propulsive force produced on the superconducting tapered tube will be about nine times larger.

Moreover because H_m is larger when the solenoid is made smaller in diameter and positioned at the narrow end of the tapered tube, its magnetic resistance will also be larger, and this will tend to diminish the overall magnitude of its magnetic flux as compared with a solenoid placed at the wide end of said tube. Consequently, this is another reason why a solenoid at the wide end of the tapered tube will develop a stronger propulsive force.

Furthermore, for a solenoid that spans the wider end of the tapered tube and which consequently has a large cross-sectional area, the field strength will decline with distance much less rapidly than a magnetic field source placed at the narrower end of said tube. So this too contributes to an improvement in the exerted propulsive force when the magnetic field source is placed at the wide end of the tapered tube. Also by placing the solenoid at the wide end of said tapered tube, it is beneficial to reduce the length of the tapered portion of the tapered tube (2a) so as to be more steeply tapered than is shown in the 2009 disclosure. Reducing the length of this tapered portion will increase the magnetic field intensity within said portion and result in an enhanced propulsive force acting on said tapered tube. How the magnetic field intensity within the tapered tube depends on the length of the tapered portion of said tube may be illustrated by means of the following equation (Eq. 8):

out tu e externa externa where J Hdl is the intensity line integral outside of the solenoid, J Hdl is the intensity line out tube

integral inside of the tapered tube, and j Hdl is the intensity line integral outside of the

external

tapered tube. The line integral for the tube portion may be approximated as the product of the average magnetic intensity within the tube, H_lube , with the length of the tube, L_tube .

Consequently, under the condition that J Hdl remains constant, the average field

external

intensity within the tube, H_tube , will increase as the length of the tube, L^, decreases, and this will consequently increase the propulsive force on the tapered tube which varies as B². Shortening the length too much however, will increase the magnetic resistance which could reduce the value of J Hdl and thereby lead to a reduction of average (H^). The optimum

out

length of the tapered tube in the present invention is defined with the aim of maximizing the propulsive force F, all other parameters being held constant. The optimal tube geometry for producing a maximal force may be found by means of simulation with an appropriate software program, e.g. «Quick Field, Finite Element Systems, User's Guide Version 5.3 - Terra Analysis Ltd (2005)» or by means of experimentation.

One other consideration is the position of the magnetic field source within the superconducting tube. In the previous 2009 disclosure (FIG. 4 prior art), the magnetic field source is shown projecting out from the end of the cylindrical portion (2b) of the tapered tube. This placement results in a diminished magnetic flux returning through the wide end of the tapered tube to the opposite magnetic pole of the source. This is because a portion of the magnetic flux from the projecting pole of the magnetic field source returns to said field source by passing into the unshielded side of said field source and hence does not make the circuit back through the wide end of the tapered tube. The current embodiments, which place the solenoids entirely within the superconducting tube enclosure avoid this problem and consequently develop greater magnetic field intensities and thrusts within the tapered tube throat.

Use of a tapered solenoid placed within and spanning the length of the throat of said tapered tube, as shown in FIG. 3, will produce a magnetic field strength within said tapered tube that is greater still than that produced by placing a solenoid at the wide end of said throat; as shown in FIG. 1. Hence due to the close proximity between said magnetic field generating source and said superconducting tapered tube, this embodiment will yield a greater propulsive force on said tapered tube. By placing magnetic field sources or solenoids at both the wide end and narrow end of said tapered tube with the poles of said sources being similarly aligned to create mutual attraction, as shown in FIG. 2, the field strength within said tapered tube will be greater in comparison to the field strength of a single magnetic field source placed just at the wide end of said tapered tube. Consequently, if magnetic field sources are placed at both the inlet and outlet of said tapered tube, the resulting increase in magnetic field strength within said tapered tube will result in a greater propulsive force being exerted on said tapered tube as compared with use of a single magnetic field source. Hence in the present invention, the diameter and arrangement of the magnetic field sources being used is changed from that presented in the preceding 2009 disclosure. Temperatures in the range of 40 to 50 K have been obtained in outer space on spacecraft in Earth orbit that have been shaded by a sunshield, as in the case of the James Webb Space Telescope. Consequently, in application to the propulsion of a satellite or spacecraft in outer space, the present invention may not require cooling to maintain the superconductive state of its tapered tube if said tube is fabricated from a type II superconductor.

In the above disclosed magnetic propulsion device, it is useful to be able to control the magnitude of the propulsion force or even turn it off. One way of doing this is by controlling the magnitude of the magnetic flux produced by the solenoid (3) or by changing its position relative to the tapered tube throat. Another way of doing this is to change the temperature of the superconductor shield which in turn changes the magnitude of the trapped magnetic flux. As seen in FIG. 5, the magnitude of the magnetic flux trapped in a type II superconductor varies with the superconductor's temperature, increasing as the superconductor's temperature progressively drops below its critical temperature. As a result, at progressively lower temperatures, an external magnetic field will exert a progressively greater force on the superconductor shield. On the other hand, if the superconductor's temperature is allowed to rise above its critical point, its trapped flux will approach zero and the propulsive force on the shield will shut off. Once cooling is restored to its shield, said propulsive device will again generate a propulsion force. One way of regulating the temperature of the superconductor shield is by changing the speed of the heat pump cooler used to refrigerate the shield or, if a thermoelectric cooler is used, by changing the voltage on the Peltier cooler. Alternatively, by turning said cooler off entirely to allow the superconductor to heat up above its critical point, the propulsive force will shut off Alternatively, the temperature of the superconductor shield may be raised or lowered by making or breaking the thermal contact path between said shield and its cooler, for example by means of an actuator relay. In outer space where the temperature is sufficiently low for superconductivity the temperature of the superconductive tapered tube may be controlled by means of an electrical heater. Experiment

An experiment was performed by A. Nassikas in April 2012 in a closed laboratory room free of air currents. A tapered tube was constructed which had a form similar to that shown in FIG. 2. Said tapered tube (2) was made of the type II superconductor YBCO (Yttrium— Barium— Copper— Oxide) and designed with a wall thickness of 7 mm and a taper of 45° connecting its wide end (3.5 cm ID) to its narrow end (1.29 cm ID). Magnetic field sources (3) and (4) of 0.5 T were fixed at each end of said tapered tube to produce an axial magnetic field that was coaxially aligned with the tapered tube's axis of symmetry. The propulsion device (1), consisting of the tapered tube and its attached magnetic field sources, was suspended at the end of a Teflon thread P, which was secured to a fixed point d on a rigid support (7) to form a pendulum; see FIG. 6. Said propulsion apparatus was immersed in a bath of liquid nitrogen (8) retained within insulated container. A second nonmagnetic pendulum bob (9) was hung from point 0₂ by thread P₂ so as to serve as a reference plum adjacent to the main pendulum. A black backdrop (10) was placed behind the pendulum bobs to increase the visibility of their threads. When the YBCO tapered tube became superconducting, the propulsion device was seen to move from its plumb position. Thread Pi was witnessed to become displaced laterally from P₂ by S = 2.0 cm for a vertical thread segment length measuring L = 80 cm. That is, P, made an angle of 1.4 degrees relative to P₂. The propulsion device weighed w = 200 grams. So, the superconducting tapered tube device was being displaced horizontally by a force of F = w x S/L = 5 grams. Thus the test was witnessed to have a positive result. The magnetic field source (3) of the propulsion device is estimated to have produced a trapped flux of approximately 0.07 Tesla in the

superconducting tapered tube.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention.

Claims

1. An apparatus for developing a propulsive force comprising:

a superconductor magnetic field shield means configured in the form of a tapered tube;

and magnetic field generating means installed entirely within said tapered tube, said magnetic field generating means further comprising an arrangement of magnetic field generating means capable of creating a strong magnetic field wherein said tapered tube is cryogenically cooled to maintain it in a superconducting state.

2. An apparatus for developing a propulsive force according to claim 1 wherein the superconductive material from which said tapered tube is a type II superconductor.

3. An apparatus for developing a propulsive force according to claim 2 wherein the means for creating a strong magnetic field is a solenoid which is installed within a portion of constant cross section at the narrow end of said tapered tube.

4. An apparatus for developing a propulsive force according to claim 2 wherein the solenoid has a magnetizable core.

5. An apparatus for developing a propulsive force according to claim 2 wherein the solenoid is a superconducting solenoid.

6. An apparatus for developing a propulsive force according to claim 2, wherein the means for creating a strong magnetic field comprises a pair of solenoids, said solenoids being installed within portions of constant cross-section in the corresponding ends of the convergent region of said tapered tube.

7. An apparatus for developing a propulsive force according to claim 2, wherein the means for creating a strong magnetic field is a convergent solenoid located in the convergent portion of the tapered tube and wherein the entire tapered tube is the convergent region thereof.

8. An apparatus for developing a propulsive force according to claim 7, wherein said convergent solenoid is a convergent superconductive solenoid.

9. An apparatus for developing a propulsive force according to claim 2, wherein said solenoid is supplied with power from a source of direct or alternating current.

10. An apparatus for developing a propulsive force according to claim 2, wherein the means for cooling said superconductor magnetic field shield means is a cryogenic material.

11. An apparatus for developing a propulsive force as claimed in claim 2 wherein means for cooling said superconductor magnetic field shield means is a heat engine.

12. An apparatus for developing a propulsive force as claimed in claim 2 wherein means for cooling said superconductor magnetic field shield means is a thermoelectric cooler.

13. An apparatus for developing a propulsive force as claimed in claim 2, comprising:

control means for varying the temperature of said superconducting shield in a controlled manner to change the superconductive state of said magnetic field shield.

14. An apparatus for developing a propulsive force as claimed in claim 2 wherein

said means for cooling said magnetic field shield means is a sunshade.

15. An apparatus for developing a propulsive force as claimed in claim 2 wherein means for controlling the temperature of said superconductor magnetic field shield means is an electric heater.

16. An apparatus for developing a propulsive force, comprising:

a tapered tube composed of a type II superconductor; and

a solenoid for creating a magnetic field wherein the solenoid is fixed entirely within said tapered tube and wherein a primary magnetic field axis of said solenoid is coaxial with the axis of symmetry of said tapered tube.