The field of the disclosure relates generally to electromagnetic projectile launching, and more particularly, to apparatus, methods and systems for electromagnetic projectile launching.
Known electromagnetic launching systems generally utilize an electromagnetic force, particularly the Lorentz force, to accelerate and launch a projectile. Two common types of electromagnetic launch systems are railguns and coilguns.
In a typical railgun system, a launch package slides between a pair of generally parallel rails. The launch package includes a payload coupled to an armature that functions as a sliding switch or an electrical short between the rails. In at least some known systems, launch packages include a sabot. By passing a large electrical current through one rail, through the armature, and back along the other rail, a large magnetic field is generated behind the launch package. The rapidly changing magnetic field within the boundaries of the two rails accelerates the launch package to a high velocity accordingly.
Electromagnetic coilgun systems include one or more electrical coils. In some systems, the coils surround a barrel. A launch package, including a payload and an armature, is positioned within the barrel. In other systems, the coils do not surround a barrel and the payload and/or armature surrounds the coils. In either type of system, when the electrical coils are energized, magnetic fields are generated along the length of the coilgun. In multi-coil coilguns, sequentially switching the electrical coils produces a wave of magnetic energy that travels along the length of the coilgun. Some coilguns push the launch package down the length with a magnetic field behind the package, while others both push and pull the launch package (referred to as push-pull) by selectively energizing coils on opposite ends of the launch package.
Both railguns and coilguns include an armature in the launch package. The armature is the portion of the launch package upon which electromagnetic forces act. In various systems, the armature is a separate item coupled to or integrated within a payload, is the payload itself, and/or is a sabot coupled to a payload. The design and operation of the armature for a railgun and a coilgun differs. However, in both types of electromagnetic launching system, the system acts on the armature to propel the launch package. The armatures are typically made from an electrically conductive material, such as iron, steel, copper, aluminum, etc. In some types of coilgun systems, the armature is generally a non-ferromagnetic material, such as copper or aluminum.
In one aspect of the present disclosure, a projectile for use with an electromagnetic launcher is provided that includes an armature including a superconductor material. The armature is configured for coupling to a payload and configured for acceleration by the electromagnetic launcher.
In another aspect of the present disclosure, a method is provided for use in making a projectile for an electromagnetic launcher. The method includes providing an armature including a superconductor material configured for coupling to a payload and configured for acceleration by an electromagnetic launcher. The method includes cooling the armature to at least a temperature at which the superconducting material enters a superconducting state.
In a further aspect of the present disclosure, an armature for use with an electromagnetic launcher is provided. The armature includes a superconductor material having a toroidal shape, and a reinforcement material wrapped about the superconductor material.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps unless such exclusion is explicitly recited. Furthermore, references to “one embodiment”, “one implementation”, the “exemplary embodiment” or the “exemplary implementation” are not intended to be interpreted as excluding the existence of additional embodiments or implementations that also incorporate the recited features.
The exemplary apparatus, methods, and systems described herein relate generally to electromagnetic projectile launching. More particularly, the exemplary implementations relate to superconducting armatures for electromagnetic projectile launching.
System 100 includes a cooler 110 that reduces the temperature of a superconducting armature (not shown in
The aforementioned two properties of superconductors enable superconductors to function as powerful artificial magnets and facilitate efficient acceleration in an electromagnetic launch system. In other implementations, cooler 110 does not generate a magnetic flux, and the armature is transitioned to a superconducting state without a trapped magnetic flux. In still other implementations, system 100 does not include cooler 110, and the superconducting armature is loaded into system 100 already cooled, with or without a trapped magnetic flux, to the superconducting state by a different system. In the exemplary implementation, the superconducting material of the armature has a trapped magnetic field, whether generated by cooler 110 or by another system, of about ten teslas (T). In other implementations, magnetic fields of greater or lesser magnitude may be trapped in the superconducting material of the armature.
Armature 202 is fabricated from a superconductor material. In the exemplary implementation, the superconductor material is a bulk, single-crystal high temperature superconductor (HTSC). In some implementations, armature 202 is yttrium barium copper oxide. In other implementations, the superconductor material is bismuth strontium calcium copper oxide. In still other implementations, armature 202 is fabricated from any other suitable superconductor material.
Armature 202 is configured for acceleration and launching by system 100. Armature 202 is sized and shaped to fit within barrel 102. More specifically, armature 202 is configured to withstand the significant shear and radial pressures during acceleration and launch of armature 202 by system 100. In some implementations, the shear stress on armature 202 has a peak value of about 108 pascals (Pa) and a peak radial stress of about 2×106 Pa. The shape of armature 202 is selected to facilitate withstanding the acceleration and launch pressures generated on armature 202 by system 100. The shape of armature 202 may be any shape suitable for acceleration and launch by system 100.
In the implementation shown in
As shown in
System 800 includes a cooler 810 that reduces the temperature of a superconducting armature 812 to and/or below a temperature at which the superconducting material used in fabricating armature 812 is transitioned to a superconducting state. Moreover, in the exemplary implementation, cooler 810 generates a magnetic field through the superconducting material of the armature as the material is being cooled to the transition temperature. Superconductors have a flux-trapping property such that a magnetic flux will be trapped in the superconductor if it is present when the material crosses the temperature threshold between conducting and superconducting states, sometimes referred to as the “critical temperature”. Moreover, once the superconductor material becomes superconducting, the superconductor will reject any further imposition of magnetic flux. This property is referred to as flux-exclusion. In other implementations, cooler 810 does not generate a magnetic flux, and the armature 812 is transitioned to a superconducting state without a trapped magnetic flux. In still other implementations, system 800 does not include cooler 810, and the superconducting armature 812 is loaded into system 800 already cooled, with or without a trapped magnetic flux, to the superconducting state by a different system. In the exemplary implementation, the superconducting material of the armature has a trapped magnetic field, whether generated by cooler 810 or by another system, of about ten teslas (T). In other implementations, magnetic fields of greater or lesser magnitude may be trapped in the superconducting material of the armature.
An exemplary projectile package 814 includes armature 812 and a payload 816. Armature 812 is coupled to payload 816 and is configured for acceleration by system 800. In the exemplary implementation, armature 812 is attached externally to payload 816. In other implementations, armature 812 may be integrated with payload 816. In still other embodiments, armature 812 is the payload (i.e., the armature is being launched by system 800 without a separate payload 816). Moreover, in some implementations armature 812 is permanently (or semi-permanently) attached to payload 816, i.e., armature 812 launches from system 800 and is delivered to a target with payload 816. In other implementations, armature 812 is removably coupled to payload 816 and is detached from payload 816 when payload 816 leaves rails 802 and 804 or shortly thereafter. In some embodiments, armature 812 is a sabot attached to payload 816.
Armature 812 completes an electrical circuit between rails 802 and 804. In operation, controller 806 couples current from source 808 to rails 802 and 804. Electrical current flows down rail 802, through armature 812, and returns through rail 804. This current creates a magnetic field inside the loop formed by the length of rails 802 and 804 up to the position of armature 812. Because the current is in the opposite direction along each rail 802 and 804, the net magnetic field between the rails is directed at right angles to the plane formed by the central axes of the rails 802 and 804 and armature 812. This produces, in combination with the current, a Lorentz force which accelerates armature 812 along the rails 812
The exemplary methods and systems described herein provide highly efficient electromagnetic launch systems and projectiles. An armature constructed from superconducting material operates more efficiently than similar armatures constructed of non-superconducting systems. Magnetic field strengths much greater than those attainable using non-superconducting materials may be obtained by using superconducting armatures. Moreover, efficiency increases may also be obtained by trapping a magnetic field in the superconducting material of the armature. Wrapping the superconducting armature with reinforcing material facilitates increasing the stability and strength of the superconducting material. Armatures configured in accordance with the present disclosure may be shaped to withstand the shear and tensile stresses induced on the armature during acceleration by an electromagnetic launching system. The described implementations permit simple launching using push only systems with pulsed magnetic fields. Strong trapped magnetic fields permit high velocities with shorter barrel lengths, more efficient magnetic coupling, and lower pulsed power requirements than in systems using other known magnetic materials.
The description of the different advantageous embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous embodiments may provide different advantages as compared to other advantageous embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated. This written description uses examples to disclose various embodiments, which include the best mode, to enable any person skilled in the art to practice those embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
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