Patent Application
20160086724
Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to conductor assemblies and methods of forming both wiring assemblies and systems incorporating conductor assemblies which, when conducting current, generate a magnetic field or which, in the presence of a magnetic field, induce a voltage. Such wiring, or conductor, assemblies may be components used in systems that rely on the generation of large and uniform magnetic fields.
2. Background Art
It is of continued importance across many sectors of the world economy (e.g., research and development, medical applications, rotating machines, and the like) to achieve improved performance in magnetic conductor assemblies. Development of new and improved commercial applications is dependent on an ability to create large and uniform magnetic fields. Advancements are also needed in numerous performance and reliability factors to realize commercially useful embodiments in medical, industrial and commercial applications. For example, it is desirable to make charged particle therapy cancer treatment (e.g., proton and carbon therapy) more available to patients, but these systems require cyclotrons that utilize very large magnets to steer beams of high energy charged particles. System size and cost severely limit the availability of these applications. Currently, the gantries used for proton therapy treatment rooms may extend multiple stories in height and weight over one hundred tons. One impediment to further deployment of these and other charged particle beam systems is the size and cost of the beam acceleration and focusing equipment.
Numerous magnet applications require provision of a magnetic field on the inside or the outside of a cylindrical structure with a varied number of magnetic poles. Examples of such applications are use of magnets for charged particle beam optics such as used in particle accelerator applications, particle storage rings, beam lines for the transport of charged particle beams from one location to another, and spectrometers to spread charged particle beams in accord with particle mass. Magnets of various multipole orders are needed for charged particle beam optics. In such charged particle beam applications dipole magnets are needed for steering the particle beam, quadrupoles are needed for focusing the beam, and higher order multipole magnets provide the optical equivalent of chromatic corrections.
Field errors (i.e., deviations from the ideal field strength distribution for a given application) in such systems are known to degrade the performance of the beam optics, leading to a rapid increase in beam cross sections, or beam loss within the system. Analogous to light optical systems, for which the lenses conform to predefined geometries and are ground accordingly with very high precision to render satisfactory resolution of the transmitted image, optimal performance of magnets in charged particle beam systems is dependent on creation of optimal positioning of conductor in winding configurations. This includes achievement of mechanical tolerances which result in very close conformity of the fabricated systems with predefined configurations to achieve necessary field uniformity. This is recognized for a variety of magnet designs, including double helix magnets and saddle coil magnets. See, for example, the following patent applications, each now incorporated herein by reference: U.S. 2009/0251257 filed Apr. 2, 2008, U.S. Pat. No. 7,992,884 filed Jun. 5, 2008 and PCT/US 2013/73749.
Numerous winding configurations for single-helix, double-helix, saddle coil and other conductor configurations can be manufactured by machining grooves into composite or metallic support structures, into which a conductor is inserted and, as needed, bonded into place with appropriate adhesives. The machined grooves precisely define the conductor layout of the winding and simultaneously stabilize the conductor mechanically to counteract Lorentz forces that act within the coil windings. Winding configurations of the types mentioned above, as well as the embodiments disclosed herein, typically surround a cylindrical aperture, with the conductor inserted into machined grooves to follow a 3-dimensional space curve.
The current-carrying conductor configurations used for charged particle beam optics are typically of cylindrical shape, with the conductors surrounding a tube, also of cylindrical shape. During operation, the tube is evacuated and a particle beam of narrow width passes along the central axis of the tube. The field-generating winding configurations for such applications, in most cases, consist of multiple saddle shaped layers of winding. Each layer comprises multiple turns of winding as shown in
The present invention is based, in part, on recognition that definition of the conductor configuration in, for example, a saddle coil magnet (i.e., the conductor path) and accuracy of conductor placement in the winding configuration are critical to acquiring satisfactory or optimal field uniformity, especially in the case of large magnets (e.g., magnets having lengths on the order of about 15 m) and in the case of superconducting windings. With recognition that numerous applications of magnetic fields, in addition to those related to charged particle beam optics, have potential for improved performance based on improved field uniformity, practical limitations in conventional fabrication processes may adversely affect field uniformity or limit magnet size. Field uniformity may be compromised by limitations in the fabrication process when the required magnetic coils are several meters long, as is often required for coil structures. Examples of magnets requiring large coil lengths are the bending magnets used in large accelerators like the Large Hadron Collider (LHC) near Geneva, which includes magnets having lengths of about 15 m. However, due to superior winding support and field quality achievable with machined grooves, such coil configurations of the types disclosed in the '749 application are best suited for future high field accelerator magnets having field strengths on the order of 16 to 20 Tesla.
The present invention provides a method of manufacturing and assembling segmented support structures for conductor assemblies and magnets, including magnets comprising coil windings which are multiple meters in length. The support structure into which the machined grooves are formed to define the conductor path may consist of a composite material or may be a metal in the shape of a cylinder, but which need not be manufactured in the form of a single piece of stock. Rather, the support structure may be formed in multiple connectable support structure segments. The plurality of segments includes multiple individual segments, each of sufficient length to support multiple individual coil turns in a helical or other desired conductor configuration. When the segments are connected, a contiguous desired conductor configuration, which may, for example, be helical, is formed and continues without interruption from connectable segment to connectable segment.
In the long term, for charged particle therapy and certain other high magnetic field applications, it is likely that superconducting magnets will be preferred over resistive magnets. Generally, superconducting magnets offer very stable and high field strengths and can be substantially smaller in size than resistive magnets. Moreover, the power demands of superconducting magnets are very low. However, the opportunity to provide superconducting magnets in new applications may be compromised because of the well-known quenching phenomenon. When the superconducting material undergoes an unexpected and rapid transition to a normal, non-superconducting state this can result in rapid formation of a high temperature hot spot which can destroy a magnet. Designs which improve reliability have been costly. Cost is a major constraint to greater commercialization of conventional superconducting magnet technologies which rely on saddle or racetrack coils. Moreover, for a given set of operating conditions, significant design efforts must be employed to achieve requirements of field uniformity and to assure that quenching does not occur during normal system use.
Whether future systems employ resistive or superconductive windings, a need will remain to improve design efficiency, reliability and field quality. In order to deploy carbon-based systems for charged particle cancer treatment, for example, the use of superconducting magnets may be imperative in order to meet the bending requirements of the high energy carbon beam. Coil segments used to bend beams are very complex to manufacture and must be very stable in order to implement a curved trajectory. Further, it is very difficult to apply conventional geometries, e.g., saddle coil and race track configurations, to curvilinear applications in an easily manufacturable manner and still meet requirements for field configurations.
Thus there exists a need for an easily manufacturable conductor assembly to be utilized in magnetics applications, that will support the manufacture and assembly of any winding or conductor configuration.
The present invention provides a segmented wiring support structure and method of manufacturing and assembling conductor assemblies for magnets, including magnets comprising coil windings which may be multiple meters in length, that provide an easier and lower cost method of manufacture that the designs and methods of the prior art.
In an embodiment, the support structure of the invention comprises a cylinder in which machined grooves are formed in segmented support structures to define the conductor path. The conductor path may be any configuration such as helical, saddle coil or otherwise. The segments may be manufactured of a composite material or a metal in the shape of a cylinder having an inner diameter, an outer diameter and an axis, but which need not be manufactured from a single piece of material. Rather, the support structure may be formed in multiple connectable segments which, when connected together, form a completed wiring support structure. In an embodiment supporting a helical conductor configuration, each support segment structure may be of sufficient length, for example, to support multiple individual conductor turns in a helical configuration. When the segments are connected the helical configuration continues without interruption from connectable segment to connectable segment. The segmented wiring support structure of the invention may be applied to linear magnet geometries, curved magnet geometries or a combination of linear and curved magnet geometries. Multiple concentric layers of conductor configurations may be formed in which each layer of conductor is in grooves in segmented support structures comprising a cylinder, wherein each cylinder is concentrically disposed about an axis. Thus each cylinder has an axis, and the axes of the cylinders formed by the segmented supported structures are coaxially disposed. In this manner any number of layers of conductor configurations may be supported by the segmented structures of the invention.
In accordance with one embodiment of the present invention, the invention comprises a wiring support structure that is formed in discrete wiring support elements which may be individually manufactured and the joined together to form a completed wiring support of a desired geometry.
Embodiments of multi-segment configurations of the invention include mass produced cylindrically shaped segments and multi-layer structures comprising concentrically positioned cylindrical segments residing in different cylindrical planes about a central axis. Multi-layer structures may include spaced-apart rows of helically wound conductors where the winding may spiral around a central axis or may spiral within a cylindrical surface.
Mass production methods may be used to fabricate the support structure segments of the invention. The support structure segments of the invention may be molded, for example, of a resin composite material. Likewise the support structure segments of the invention may be cast, for example, of a metal material. For metallic support structures there may be a segmentation into very short segments like transformer laminations which are stamped and united to produce the basic shape of each segment.
Another application, for which segmentation of a coil structure into shorter sections is of substantial advantage, is for bent, or curved, magnets, which have an axis that is curved, or for which a portion of the axis is curved, as depicted in U.S. Pat. Nos. 7,889,046 and 7,880,578. While it is possible to rotate a bent support structure in order to machine the conductor support grooves in a surface of the support structure, this becomes more and more difficult for bends or curves that extend beyond angles much larger than 45 degrees. The segmented wiring support structure and method of manufacturing and assembling conductor assemblies of the invention allow a linear or curved conductor support structure to be fabricated in segments, making manufacturing much easier. As an example, in the case in which a curved magnet extends to an arc of 360 degrees, identical segments of, for example 30 degree arcs, could be fabricated using the segmented wiring support structure and method of manufacturing and assembling conductor assemblies of the invention, making manufacturing much easier.
The segmentation of a conductor support structure as is a feature and object of the invention that is applicable to any conductor configuration such as, for example, helix, multi-layer helix, saddle coil, and any other desired conductor configuraion. For curved conductor structures comprising multi-layer windings, winding segments of different layers are in the form of concentric shapes having a constant radius of curvature. This permits each outer level of support structure segments to be positioned about, e.g., to slide over in a sliding engagement, an inner level of support structure segments. This arrangement may form a series of co-axial multi-layer segments. Several large multilayer segments, each comprising sections, may have different radii of curvature. When connected in series the segments can provide a path of variable curvature.
The present invention overcomes the shortcomings of the prior art in that it enables manufacturing of wiring support structures that heretofore were either difficult or impossible to manufacture and produce.
The present invention provides a method of manufacturing magnets, including magnets comprising coil windings which are multiple meters in length. In one embodiment, the support structure into which the machined grooves are formed to define the conductor path may consist of a composite material or a metal in the shape of a cylinder, but which need not be manufactured in the form of a single piece of stock. Rather, the support structure may be formed in multiple connectable segments. The plurality of the segments include multiple individual segments, each of sufficient length to support multiple individual coil turns in a helical configuration. When the segments are connected the helical configuration continues without interruption from connectable segment to connectable segment.
As used herein, the terms coil, spiral, helix and helical include but are not limited to regular geometric patterns. In addition, the terms coil, spiral and helix include configurations wherein a width (e.g., along the axial direction) or a thickness (e.g., along a radial direction or transverse to the axial direction) may vary. Further, terms such as winding, helical winding, wiring pattern and coil configuration as applied to physical embodiments formed of various conductor and/or insulative materials, are used without regard to how the materials are formed in place. That is, although it is conventional to physically wind a strand of conductor in the configuration of a spiral, the foregoing terms as used herein refer to the resulting configuration and not the methodology used to form the pattern. So, for example, a coil or winding may be formed from a cylindrical body by removal of body material, this resulting in a shape that corresponds to a spiral winding. In addition, the void resulting from the removal of material may also correspond to a spiral shape.
With coils helically-wound about an axis to produce magnetic field components transverse to the axis, cancellation of axial field components can be effected by the formation coils in concentrically positioned pairs having opposite tilt angles, this sometimes resulting in a high quality transverse field, e.g., a uniform dipole with essentially no higher order components. See, for example, Goodzeit et al., “The Double-50 Helix Dipole-A Novel Approach to Accelerator Magnet Design”, IEEE Transactions on Applied Superconductivity, Vol. 13, No. 2, June 2003, pp. 1365-1368, which describes analytics for a double helix magnet geometry, incorporated herein by reference in its entirety. See, also, U.S. Pat. No. 6,921,042 incorporated herein by reference in its entirety.
Conductor assemblies used for magnets preferably comprise channels, or grooves, in which one or more conductors may be disposed. The formation of grooves into which a conductor is inserted provides precise conductor positioning and stabilization while also isolating portions of the conductor from other portions of the conductor. The channel profile is not limited to accommodating round wire or cables. Other conductors having square or rectangular shapes in cross section, or tape, can be used in conjunction with channels. The channel may have a cross section be configured to match the cross sectional shape of the conductor. The conductor pattern and the corresponding channel path can be formed in a relatively tight helical configuration wherein the advance per turn in an axial direction is so small that portions of the conductor in adjacent turns come very close or into contact with one another. In embodiments where contact between adjacent portions of conductor turns is a concern, the conductor has an insulative coating. As used herein, “channel” and “groove” are used interchangeably.
When the channels accommodate square or rectangular cross sectional shapes of conductor, including tape, to minimize deformation in conductor, e.g., twisting, a helical channel can be formed at a variable angle with respect to a central axis, which may be the axis of the wiring supporting structure, or reference surface. In such embodiments, the resulting field will differ from that which is generated for a conventional conductor of circular cross sectional shape. A channel for a circular shaped conductor will not follow the same path as a channel formed at such variable angle to accommodate a rectangular shaped conductor without shape deformation.
The term “conductor” as used herein refers to a string-like piece or filament of relatively rigid or flexible material, commonly referred to as cable or wire, being of the type comprising either a single conductive strand or multiple ones of such strands grouped together as one functional conductive path. The term multi-strand conductor refers to such a conductor formed as a single identifiable unit and composed of multiple conductive strands which may be twisted, woven, braided or intertwined with one another to form an identifiable single unit of wire. Multi-strand conductor may take the form of conductor that embodies a circular or a non-circular cross section. Conductors may be superconducting.
The term cross section refers to a section of a feature, e.g., of a conductor or an aperture or a coil, taken along a plane which is transverse to a definable axis through which the feature extends. If the coil row axis is curvilinear about a point of interest on the axis, the plane along which the cross section is taken is understood to be transverse to the direction of a vector which is tangent to the direction of the axis at the point of interest.
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Referring next to a view of a partially assembled segmented support structure of
The full groove turns 32 and partial groove turns 32′ of the inner support structure segments 24 shown in
In an alternate method of assembly, the inside diameter D1′ of each inner support structure segment 24, which may be formed of a resin composite material, may be substantially equal to the outside diameter D1 of center tube 20. Prior to installation of each inner support structure segment 24 over center tube 20, a temperature differential may be created between the tube 20 and the inner support structure segments 24 that sufficiently reduces the outside diameter D1 of center tube 20 relative to the inside diameter D1′ of the inner support structure segments 24 in order to enable each inner support structure segment 24 to slide over center tube 20 into a desired position, and permit alignment of adjoining partial groove turns 32′ along abutting end faces 26 and 28 of adjacent inner support structure segments 24. Once installation is complete, and center tube 20 and inner support structure segments 24 come into thermal equilibrium, the diameters D1 and D1′ again become substantially equal or a slight press fit, locking center tube 20 and inner support structure segments 24 together. The temperature differential between the tube 20 and the inner support structure segments 24 may, for example, be created by active chilling of center tube 20 prior to or during the assembly process. In this manner, an assembled inner support structure 22 of the invention may be fabricated and assembled having a contiguous groove of a desired inner conductor layer configuration, for example helical, saddle coil or otherwise as may be desired by a user, along its outer diameter.
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With this arrangement, assembly of a segmented support structure of the invention may comprise any number of layers of concentric support structures concentrically positioned about ceneter tube 20 and coaxial thereto0. Thus, the segmented support structure of the invention 10 may have a single groove 36 or multiple grooves formed in any desired number of concentric cylindrical layers. Further, each of the grooves may be of sufficient depth to stack multiple conductors in a single groove, resulting in multiple coils, as described in FIG. 8 of PCT/US2013/73749. A magnet comprising the segmented support structure of the invention may therefore comprise any number of layers of segmented support structures, each layer comprising a contiguous groove for holding a conductor, the groove comprising any desired configuration such as helical, spiral, saddle coil or otherwise. It is not necessary that each layer comprise similar groove configurations as the other layers.
Referring to
An embodiment of the invention has been illustrated for helical coil designs, including double helix designs and single helix designs as described in U.S. Pat. Nos. 6,921,042 and 7,893,808. The invention may also be practiced by using saddle coil conductor configurations such as described in PCT/US2013/73749, including embodiments where none of the segments incorporate complete turns and not all segments are identical. Thus the invention is not limited to a specific conductor geometry such as saddle coil, single helix, or double helix configurations. For example, a series of identical segments may be provided for mounting about a tube structure to construct the straight sections of multiple saddle coil winding configurations in a dipole or quadrupole or higher order design, while segments providing portions of the curved paths may contain differing groove patterns.
Although exemplary embodiments have been described, numerous variants are included within the scope of the claims. For example, the segments which form each groove pattern (e.g., segments 24 and 54) may be formed of two half cylinder portions that are placed about an inner structure such as tube 20. In this embodiment, the half cylinder portions forming the inner and outer support structure segments in the case of a two layer segmented support structure may be joined by any means known in the mechanical arts such as, for example, and not by way of limitation, chemical bonding, threaded fasteners or other attachment means.
A support structure 22 has been illustrated as comprising a series of identical cylindrically shaped sections, but in other embodiments of the invention a support structure may comprise sections of differing length, curvature or groove pattern. As noted, differing sections may be assembled to form a saddle coil configuration. In another example, the segments could differ in order to vary the multi-pole order of the configuration, or to provide flared conductor assembly ends.
Referring now to
In a single helix embodiment, the segmented support structure for a helical conductor assembly of the invention may comprise a plurality of support structure segments, wherein each support structure segment is defined as a tubular shape formed about an axis, each segment having a length, and each support structure segment further comprising a first end face and a second end face, each end face transverse to said axis and wherein each support structure segment is further defined as having an outer surface defined by an outer diameter, said outer diameter of each support structure segment further comprising a plurality of grooves for containing a conductor. The plurality of grooves of the plurality of support structure segments may together form a contiguous helical groove disposed about an axis, the helical groove axis having a curved portion, when said support structure segments are disposed such that said first end faces and said second end faces of said plurality of support structure segments are in contact with one other forming a cylinder having an axis, said helical groove forming an aperture region, such that when a conductor is disposed in said contiguous helical groove, a magnetic field having multi-pole components oriented in directions transverse to the axis is capable of being sustained; wherein the aperture region extends outward from the axis a radial distance to the contiguous helical groove; and wherein a conductor contained in said contiguous helical groove capable of generating a magnetic field in the curved aperture region along a plane passing through a point along the curved segment of the contiguous helical groove; and the magnetic field along directions parallel to the plane includes a first dominant component of multi-pole order A and one or more second components each of different order than A, wherein at 80 percent of the radial distance the field contribution along the plane by each of the one or more second components is at least 103 times smaller in magnitude than the magnitude of the first dominant component of order A.
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The segmented wiring support structure of the invention may form any number of coaxial conductor layers, and each conductor layer need not be of the same conductor configuration as the other conductor layers, i.e. single helix, double helix, saddle coil, or otherwise.
Although specific embodiments of the segmented wiring support structure are described and depicted in the specification, drawings, and claims, the scope of the claims includes equivalent structures and steps, and thus the scope of the invention is not to be limited to the exemplary embodiments depicted in the figures.
This non-provisional application for patent filed in the United States Patent and Trademark Office (USPTO) under 35 U.S.C. §111(a) claims the benefit of provisional application Ser. No. 62/053,360, which was filed in the USPTO on Sep. 22, 2014, and which is incorporated herein in its entirety by reference. The following U.S. patents are each herein incorporated by reference in their entirety: U.S. Pat. No. 7,889,046 titled CONDUCTOR ASSEMBLY FORMED ABOUT A CURVED AXIS, issued from the USPTO on Feb. 15, 2011 (“the '046 patent”); U.S. Pat. No. 7,880,578, titled CONDUCTOR ASSEMBLY INCLUDING A FLARED APERTURE REGION issued from the USPTO on Feb. 1, 2011; U.S. Pat. No. 7,990,247 titled COIL MAGNETS WITH CONSTANT OR VARIABLE PHASE SHIFTS, issued from the USPTO on Aug. 2, 2011; U.S. Pat. No. 6,921,042 titled CONCENTRIC TILTED DOUBLE-HELIX DIPOLES AND HIGHER-ORDER MULTI-POLE MAGNETS, issued from the USPTO on Jul. 26, 2015; and U.S. Pat. No. 7,893,808 titled CONDUCTOR ASSEMBLY HAVING AN AXIAL FIELD IN COMBINATION WITH HIGH QUALITY MAIN TRANSVERSE FIELD issued from the USPTO on Feb. 22, 2011. Also incorporated by reference herein in its entirety is U.S. patent publication US 20090251257 A1, published by the USPTO on Oct. 8, 2009, titled WIRING ASSEMBLY AND METHOD OF FORMING A CHANNEL IN A WIRING ASSEMBLY FOR RECEIVING CONDUCTOR AND PROVIDING SEPARATE REGIONS OF CONDUCTOR CONTACT WITH THE CHANNEL.
| Number | Date | Country | |
|---|---|---|---|
| 62053360 | Sep 2014 | US |
