Electrical connections for use in cryogenic applications

Abstract

An apparatus is described for electrically connecting a superconducting component located within a cryogenic chamber to an electrical device located outside the cryogenic chamber. The apparatus includes a coil including a plurality of helical loops and located within the cryogenic chamber, and an actuator for compressing and expanding the coil between a first state and a second state. In the first state, the coil has a first electrical resistance and a first thermal conductivity, and in the second state, the coil has a second electrical resistance and a second thermal conductivity.

Description

[Background technology]

[0001]

[0001] Superconducting devices, including superconducting magnets, are typically maintained at extremely low pressures and at extremely low temperatures (e.g., near absolute zero) by encasing the superconducting magnet in a chamber containing a coolant. These superconducting devices are used in a variety of applications, one common application being magnetic resonance imaging (MRI) systems, which are commonly used in medicine.

[0002]

[0002] Maintaining a constant low temperature in these so-called cryogenic chambers is very important for the normal operation of the superconductors that make up the superconducting magnets. Therefore, it is very important to keep the cryogenic chamber sealed so that heat from outside the cryogenic chamber does not significantly affect the temperature inside the cryogenic chamber. However, electrical connections from room temperature equipment to superconducting components (such as superconducting magnets) are essential. For example, the operation of superconducting components requires the flow of electrical current from an external power source. However, when electrically connecting an external device to a superconducting component in a cryogenic chamber, a thermal conduction path may be formed. As a result, unacceptable levels of heat may be transferred from the surroundings to the cryogenic chamber, compromising the desirable superconducting properties of the superconducting components in the cryogenic chamber.

[0003]

[0003] In a typical superconducting component (such as a magnet), a liquid helium bath is used to maintain the cryogenic temperature of the superconducting coils and accessories housed within a cryogenic chamber. In certain known systems, electrical connection to these types of magnetic coils is often provided by removable electrical leads that penetrate the pressure vessel, relying on the constant evaporation of the contained liquid helium to conduct along these leads and temporarily remove the heat generated by them. As such, these leads are inserted into the cryogenic chamber during ramp-up operation of the superconducting component, and once steady-state operation is achieved, these leads are removed to reduce the heat load on the refrigeration system. Specifically, and as known to those skilled in the art, after ramping up the magnet to full current, a superconducting switch is closed to create a loop.

[0004]

[0004] However, some superconducting magnets include a closed cooling system within the vacuum space of the cryogenic chamber that directly cools the superconducting components. In such applications, an electrical path is required to electrically connect from an electrical device (such as a power source) outside the cryogenic chamber to the superconducting components. Known connections result in unacceptable levels of thermal conductivity along the electrical connections. As a result, the use of known electrical connections can significantly degrade the performance of the superconducting components. Summary of the Invention [Problem to be solved by the invention]

[0005] What is needed, therefore, is an electrical connection between a superconducting component within a cryogenic chamber and an electrical device outside the cryogenic chamber that overcomes at least the shortcomings of the known electrical connections discussed above. [Means for solving the problem]

[0006] According to an aspect of the present disclosure, an apparatus for electrically connecting a superconducting component in a cryogenic chamber to an electrical device outside the cryogenic chamber is disclosed. The apparatus includes a coil including a plurality of helical loops and an actuator for compressing and expanding the coil between a first state and a second state. In the first state, the coil has a first electrical resistance and a first thermal conductivity, and in the second state, the coil has a second electrical resistance and a second thermal conductivity.

[0007]

[0007] According to another aspect of the present disclosure, a method of providing an electric current to a superconductor component residing in a cryogenic chamber is disclosed, the method including the steps of providing an apparatus including a coil including a plurality of helical loops, compressing the coil to a first state, where in the first state the coil has a first electrical resistance and a first thermal conductivity, and expanding the coil to a second state, where in the second state the coil has a second electrical resistance and a second thermal conductivity.

[0008]

[0008] According to another aspect of the present disclosure, a magnetic resonance imaging (MRI) system includes a magnet system including a superconducting magnet in a cryogenic chamber and an apparatus for electrically connecting a superconducting component in the cryogenic chamber to an electrical device outside the cryogenic chamber. The apparatus includes a coil including a plurality of helical loops and an actuator for compressing and expanding the coil between a first state and a second state. In the first state, the coil has a first electrical resistance and a first thermal conductivity, and in the second state, the coil has a second electrical resistance and a second thermal conductivity. [Brief description of the drawings]

[0009]

[0009] Example embodiments are best understood when the following detailed description is read in conjunction with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, dimensions have been arbitrarily increased or decreased for clarity of discussion. Where applicable and practical, like reference numerals refer to like elements.

[0010] [Figure 1] FIG. 1 illustrates a magnetic resonance imaging (MRI) system in accordance with a representative embodiment. [Diagram 2] FIG. 2 is a perspective view of an apparatus for electrically connecting a superconducting component located within a cryogenic chamber to an electrical device located outside the cryogenic chamber according to a representative embodiment. [Diagram 3]

[0011] FIG. 3 is a cross-sectional view of an apparatus for making electrical connections in a cryogenic chamber in a first state according to a representative embodiment. [Figure 4]

[0012] FIG. 4 is a cross-sectional view of an apparatus for making electrical connections within a cryogenic chamber in a second state according to a representative embodiment. [Diagram 5]

[0013] FIG. 5 is a perspective view illustrating a cross-sectional view of an apparatus for making electrical connections in a cryogenic chamber in a first state according to a representative embodiment. [Figure 6]

[0014] FIG. 6 is a perspective view illustrating a cross-sectional view of an apparatus for making electrical connections in a cryogenic chamber in a second state according to a representative embodiment. [Figure 7]

[0015] FIG. 7 is a conceptual diagram illustrating compressive and expansive forces applied by an actuator to compress an apparatus for making an electrical connection in a cryogenic chamber from a second state to a first state. [Figure 8]

[0016] FIG. 8 is a flow chart of a method for providing electrical current to a superconductor component located in a cryogenic chamber, according to a representative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0017] In the following detailed description, for purposes of explanation and not limitation, representative embodiments disclosing specific details are described to provide a thorough understanding of the embodiments according to the present teachings. Descriptions of known systems, devices, materials, methods of operation, and methods of manufacture may be omitted so as not to obscure the description of the representative embodiments. However, systems, devices, materials, and methods within the purview of one of ordinary skill in the art are within the scope of the present teachings and may be used in accordance with the representative embodiments. It is to be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. Defined terms are to be given the technical and scientific meaning of the defined terms as commonly understood and accepted in the art of the present teachings.

[0012]

[0018] In this specification, terms such as "first," "second," and "third" are used to describe various elements or components, but it should be understood that these elements or components are not limited by these terms. These terms are used only to distinguish one element or component from another. Thus, a first element or component discussed below may be referred to as a second element or component without departing from the teachings of the inventive concept.

[0013]

[0019] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in this specification and the appended claims, singular terms are intended to include both the singular and the plural, unless the context clearly dictates otherwise. Furthermore, the term "comprises" and / or similar terms specify the presence of stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0014]

[0020] Unless otherwise noted, when an element or component is said to be "connected," "coupled," or "adjacent" to another element or component, it is understood that the element or component may be directly connected or coupled to the other element or component, or there may be intervening elements or components present. That is, these and similar terms encompass the cases where one or more intermediate elements or components may be used to connect the two elements or components. However, when an element or component is said to be "directly connected" to another element or component, this only encompasses the cases where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0015]

[0021] As used herein and in the appended claims, and in addition to their ordinary meaning, the terms "substantial" or "substantially" mean to an acceptable limit or degree, e.g., "substantially thermally isolated" means that one of ordinary skill in the art would consider thermal isolation acceptable.

[0016]

[0022] As used herein and in the appended claims, and in addition to their ordinary meaning, the terms "approximately / approximately / about" mean within a limit or amount that would be acceptable to one of ordinary skill in the art. For example, "approximately the same" means that one of ordinary skill in the art would consider the compared items to be the same.

[0017]

[0023] The present disclosure is intended to describe embodiments, and / or specific features, subcomponents, according to one or more of its various aspects, and thus provide one or more of the advantages specifically set forth below. For purposes of explanation and not limitation, example embodiments disclosing specific details are described to provide a thorough understanding of the embodiments according to the present teachings. However, other embodiments consistent with the present disclosure that depart from the specific details disclosed herein remain within the scope of the appended claims. Furthermore, descriptions of well-known devices and methods may be omitted so as not to obscure the description of the example embodiments. Such methods and devices are within the scope of the present disclosure.

[0018]

[0024] The present teachings disclose an apparatus and method for providing electrical connection between sealed superconducting magnets that reduces heat loss from a cryochamber. In certain embodiments, the apparatus connects to an actuator (such as a solenoid-operated electrical switch) within the vacuum space of the cryochamber to enable electrical connection between electrical devices within the room temperature space and the superconducting magnets within the cryochamber during transient use, while substantially thermally preventing significant heat loss from the cryochamber during steady-state operation (i.e., providing substantial thermal isolation of the superconducting magnets).

[0019]

[0025] Advantageously, and as described in more detail below, the apparatus and methods of the present teachings substantially overcome the difficulties of balancing magnetic bistable behavior (i.e., ramp-up and steady-state operation), ohmic heating, heat conduction, and ice intolerance in a magnetic system. As described in more detail below, the apparatus described in connection with various representative embodiments achieves lower ohmic heating, similar steady-state heat conduction, lower transient heat conduction, and superior ice resistance compared to known electrical connections. These improvements provide improved performance in areas such as refrigeration capacity, magnet system availability, and magnet system reliability, as well as magnet manufacturability, to name a few. Finally, while various representative embodiments of the apparatus and methods of the present teachings are described in connection with a magnetic resonance imaging (MRI) system, it is emphasized that this is merely an exemplary application. More generally, the apparatus and methods of the present teachings are contemplated for use in other applications requiring electrical connection between a device in a cryogenic chamber and an electrical device that is outside the cryogenic chamber and at a higher temperature (e.g., room temperature).

[0020]

[0026] An electrical connection to the superconducting magnet provided by the apparatus of the various exemplary embodiments described below is necessary to change the state of the magnetic field. When the magnet is needed for imaging, current is passed through the superconducting coils through the apparatus in a first state to ramp up. Once the full magnetic field is achieved and the superconducting circuit is completed, the apparatus is placed in a second state. In the second state, both electrical and thermal conduction through the apparatus is approximately two orders of magnitude lower than in the first state, as described in more detail below.

[0021]

[0027] In certain circumstances, returning the device to the first state and zeroing out the voltage removes current from the superconducting coils through the device. Operation of the device is controlled by on-board magnet electronics that determine when the device can switch from the first state to the second state or vice versa. The electronics use known algorithms to determine when to operate the device based on input from a number of sensors. These electronics include a processor 112, memory 114, and actuators 304, 404, 504, which may be part of the MRI system 100 described below and function according to the method 800 described below. Alternatively, the device may be manually operated to switch between the first and second states based on the timing and sequence of ramp-up / ramp-down events.

[0022]

[0028] Although the magnet can remain in the field for very long periods (years) without external intervention, there are reasons to ramp down the superconducting magnet and then ramp it up again for operation. These reasons include, for example, preventative maintenance schedules for external magnet system components, cleaning or maintenance of the imaging suite, safety, power loss, and other common occurrences. The present teachings allow these desired ramp-up and ramp-down of the superconducting magnet to be performed without compromising the sealing of the cryo-chamber that houses the superconducting magnet. Furthermore, during relatively long periods of operation, the apparatus of various representative embodiments reduces heat loss from the cryo-chamber to an acceptable level. For illustrative purposes, the heat loss in the second state is about two orders of magnitude lower compared to the heat loss in the first state (e.g., during ramp-up).

[0023]

[0029] 1 shows an exemplary embodiment of an MRI system 100 according to a representative embodiment. The MRI system 100 includes a magnet system 101, a patient table 104 for holding a subject or patient 20, gradient coils 103 that at least partially surround at least a portion of the patient 20 for which the MRI system 100 generates an image, a radio frequency coil 105 that applies radio frequency signals to at least a portion of the subject or patient 20 being imaged and perturbs the arrangement of the magnetic field, and one or more sensors 10 that detect changes in the magnetic field caused by the radio frequency signals and the patient 20. In particular, the magnet system 101 includes a main magnet 106 that is located within a cryogenic chamber 107. The main magnet 106 includes a superconducting coil 108 that is maintained at a suitable temperature and pressure via the cryogenic chamber 107. As mentioned above, the magnet system 101 is sealed with an electrical connection via a conduit 109 and a two-state device (not shown in FIG. 1) that connects the superconducting coil 108 to a power supply (not shown) that is used to power the superconducting magnet. In particular, although the MRI system 100 is described in the singular, the term "system" shall be construed to include a collection of systems or subsystems that individually or collectively execute one or more sets of software instructions.

[0024]

[0030] The MRI system 100 also includes a power supply 110, a processor 112, and a memory 114. The memory 114 and the processor 112 together may be referred to as a controller. In certain representative embodiments, the memory 114 and the processor 112 may be components of a main system (not shown) that is used to control various components of the system. Alternatively, the memory 114 and the processor 112 may be separate elements from the main system. The controller may include a display (not shown) including, but not limited to, a light emitting diode (LED), a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a flat panel display, a solid state display, or a cathode ray tube (CRT). The controller, including the memory 114 and the processor 112, may be housed in or linked to a workstation (not shown), such as a computer or a separate assembly of one or more computing devices, a display / monitor, and one or more input devices (keyboard, joystick, mouse, etc.) in the form of a stand-alone computing system, desktop, tablet, etc., to perform one or more computer functions.

[0025]

[0031] Processor 112, which is tangible and non-transient, represents one or more processors. As used herein, the term "non-transient" is to be construed as a property of a state that persists for a period of time, rather than an eternal property of the state. The term "non-transient" specifically negates momentary properties, such as carrier waves or signals or other types of properties that exist only temporarily at any time and in any place. Processor 112 (and other processors) of the present teachings are products and / or machine parts.

[0026]

[0032] The processor 112 executes software instructions stored in the memory 114 to perform various functions including ramping up and down a superconducting magnet using the apparatus described in various embodiments herein. The processor 112 may be a general purpose processor or part of an application specific integrated circuit (ASIC). The processor 112 may also be (or include) a microprocessor, a microcomputer, a processor chip, a controller, a microcontroller, a digital signal processor (DSP), a state machine, or a programmable logic device. The processor 112 may also be (or include) a logic circuit such as a programmable gate array (PGA) such as an FPGA, or another type of circuit including discrete gate and / or transistor logic. The processor 112 may be (or include) a central processing unit (CPU), a graphics processing unit (GPU), or both. Additionally, the processor 112 may include multiple processors, parallel processors, or both. Multiple processors may be included or coupled in a single device or multiple devices.

[0027]

[0033] The memory 114 may include a main memory, a static memory, or both, and the memories may communicate with each other via a bus (not shown). The memory 114 described herein is a tangible storage medium capable of storing data and executable instructions, and is non-transient while the instructions are stored therein. As used herein, the term "non-transient" is to be interpreted as a property of a state that persists for a period of time, rather than a permanent property of a state. The term "non-transient" specifically negates the properties of a momentary nature, such as a carrier wave or signal or other type of property that exists only temporarily at any time and in any place.

[0028]

[0034] The memory 114 of the present teachings is a product and / or a machine part. The memory 114 includes one or more computer-readable media from which the processor 112 can read data and executable instructions (e.g., to execute the processes described in connection with ramp-up and steady-state operations). The memory described herein may be a random access memory (RAM), a read-only memory (ROM), a flash memory, an electrically programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a removable disk, a tape, a compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a floppy disk, a Blu-ray disk, or any other form of storage medium known to those skilled in the art. The memory of the present teachings may be a volatile or non-volatile memory, a secure and / or encrypted memory, a non-secure and / or unencrypted memory. The monitor and interface (not shown), processor 112 and memory 114 may be housed in or linked to a workstation (not shown), such as a computer or another assembly of one or more computing devices, a display / monitor, and one or more input devices (keyboard, joystick, mouse, etc.), in the form of a standalone computing system, desktop or tablet, etc.

[0029]

[0035] For illustrative purposes, the main magnet is a 1.5T (or greater) sealed MRI magnet available from Koninklijke Philips. The apparatus described below can be electrically connected to a superconducting magnet maintained at 40K with an external power supply of 300K, providing improved electrical and thermal properties compared to known connections. However, it is emphasized that the apparatus is not limited to use in MRI devices and systems, but may be implemented in one of many applications requiring electrical connections across relatively large temperature gradients that require specific desired electrical and thermal behavior. Thus, the apparatus of various embodiments of the present teachings allows for electrical connections across an interface between a relatively low temperature environment (such as a cryogenic chamber) and a relatively high temperature environment (such as room temperature).

[0030]

[0036] FIG. 2 is a perspective view of an apparatus 200 for electrically connecting a superconducting component (not shown in FIG. 2) located within a cryogenic chamber (not shown in FIG. 2) to an electrical device (not shown in FIG. 2) located outside the cryogenic chamber, according to a representative embodiment. The apparatus 200 has a first end 202, a second end 204, and a number of helical loops 206 between the first end 202 and the second end 204. As will be understood as the description proceeds, the apparatus provides an electrical path and a thermal path between the superconducting component and the electrical device. In FIG. 2, the apparatus is shown in a compressed state (sometimes referred to as a first state). This results in an increase in cross-sectional area, resulting in a decrease in electrical resistance and an increase in thermal conductivity, as compared to the apparatus 200 stretched in an expanded state (sometimes referred to as a second state).

[0031]

[0037] Device 200 is generally made of a flexible conductive material that is cut to provide seams 208 that allow for either compression in the -x direction of the coordinate system of Figure 2 or expansion in the +x direction of the coordinate system of Figure 2. To aid in understanding, the conductive material may include copper or aluminum, and device 200 in its compressed state has an axial length (x direction of the coordinate system of Figure 2) of approximately 4 inches (1 inch = 2.54 cm).

[0032]

[0038] As will be described in more detail below, when compressed, the seams 208 between adjacent helical loops 206 are beneficially substantially gap-free since adjacent helical loops 206 are in physical contact with one another. In contrast, when stretched, the seams 208 between adjacent helical loops 206 are relatively large, typically preventing one helical loop 206 from being in physical contact with an adjacent helical loop 206. By way of illustration only, in an uncompressed state, the seams 208 form a gap of approximately 0.050 inches to 0.100 inches. In particular, the gap will typically depend on the distance of movement and the force required to expand the device to a second state. Thus, the device 200 is a continuous structure that is compressible to a first state and stretchable to a second state, as will be described below, capable of changing its effective cross-sectional area and changing both electrical and thermal conductivity.

[0033]

[0039] 3 is a cross-sectional view of an apparatus 300 for making electrical connections within a cryogenic chamber 302 in a first state, according to an exemplary embodiment. Various aspects and details of the apparatus 300 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1 and 2 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0034]

[0040] The device 300 is located within a cryogenic chamber 302 and includes an actuator 304. To aid in understanding, the actuator 304 is an electrical, solenoid-operated device. More generally, the actuator 304 is one of many devices that provide a suitable force to expand / compress the device 300. These include, but are not limited to, known linear motors and translation mechanisms such as cams, pistons, or rods. As described in more detail below, the actuator 304 compresses the device 300 (in the −z direction of the illustrated coordinate system) when a connection is required to provide power from a power source (not shown) to the superconducting components. As described above, compression places the device in a first state, where the device forms an electrically (and thermally) conducting tube. In contrast, and as described in more detail below, when the superconducting components are functioning in a steady-state mode, the actuator applies a force to expand the device 300, placing the device in a second state. In the second state, the seams between the spiral loops that make up the device 300 are relatively large, typically preventing one spiral loop from physically contacting an adjacent spiral loop. As noted above, the second state results in a relatively high electrical resistance and a relatively low thermal conductivity. The device 300 is connected to the cryochamber 302 using a conduit 306. To aid in understanding, the conduit 306 is a ceramic piece (such as a ring) through which the electrical connection 308 to the actuator 304 and the device 300 is made. The conduit 306 is beneficially a poor conductor of heat, thereby reducing the heat transfer from the surroundings to the cryochamber 302 so as not to significantly affect the performance of the superconducting components located within the cryochamber. Thus, the conduit 306 typically comprises a ceramic material that provides substantial electrical and thermal isolation from the surroundings or outside the cryocontainer, along with a substantially leak-tight seal. Conduit 306 typically has a diameter of about 2 inches to about 3 inches and a thickness (in the x-direction of the coordinate system of FIG. 3) of about 0.5 inches.

[0035]

[0041] In the first state, the device 300 provides a relatively low electrical resistance path between an external electrical device and the superconducting components within the cryogenic chamber. As noted above and described in more detail below, in the compressed state (first state), the device provides a substantially solid tube having a ring-shaped cross section as shown. This ring-shaped cross section provides a cross section with high electrical (and thermal) conductivity compared to the isolated helical loops when the device 300 is uncompressed. Thus, in this first state, the electrical resistance is beneficially low compared to the electrical resistance in the second state, as described in more detail below.

[0036]

[0042] For example, when the superconducting component requires ramping up, actuator 304 compresses device 300, providing an electrical path from an external electronic device (such as a power source) through (external) electrical connection 308 to an internal electrical connection 310 that is electrically connected to the superconducting component. As can be appreciated, device 300 allows for electrical connection between an external electrical device (such as a power source) at 300K and a superconducting component (such as the magnet of an MRI device or system) that is maintained at 40K, providing improved electrical and thermal properties compared to known connections.

[0037]

[0043] 4 is a cross-sectional view of an apparatus 400 for making electrical connections in a cryogenic chamber in a second state according to an exemplary embodiment. Various aspects and details of the apparatus 400 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1-3 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0038]

[0044] The apparatus 400 resides within a cryogenic chamber 402 and includes an actuator 404. For ease of understanding, the actuator 404 is a solenoid-actuated device. As will be explained in more detail below, the actuator 404 expands the apparatus 400 (in the +z direction of the illustrated coordinate system) when the superconducting components are operating in a steady state with substantially no power being applied to the superconducting components. As noted above, the expansion of the apparatus 400 causes the apparatus to enter a second state in which the seams between the helical loops that make up the apparatus 400 are relatively large, typically preventing one helical loop from making physical contact with an adjacent helical loop. As noted above, the second state results in a relatively high electrical resistance and a relatively low thermal conductivity.

[0039]

[0045] The device 400 is connected to the cryochamber 402 using a conduit 406. To aid in understanding, the conduit 406 is substantially similar to the conduit 306 described above, being a ceramic piece (such as a ring) through which electrical connections 408 are made to the actuator 404 and the device 400. The conduit 406 is beneficially a poor conductor of heat, thereby reducing the heat transfer from the surroundings to the cryochamber 402 so as not to significantly affect the performance of the superconducting components located within the cryochamber.

[0040]

[0046] In the second state, the device 400 provides a relatively high electrical resistance path between an external electrical device and the superconducting components within the cryogenic chamber 402. As noted above and described in more detail below, in the expanded state (second state), the device presents a substantially rectangular cross-section as shown. This rectangular cross-section provides a cross-section with reduced electrical (and thermal) conductivity compared to the ring-like cross-sectional loop when the device 400 is compressed. Thus, in this second state, the thermal resistance is beneficially higher compared to the thermal resistance of the device 400 in the first state, as described in more detail below.

[0041]

[0047] For example, when the superconducting components require steady-state operation, the actuator 404 expands the device 400. Due to the relatively small conductive cross-section of the device 400, the electrical and thermal resistance of the electrical path from an external electronic device (such as a power source) through an (external) electrical connection 408 to an internal electrical connection 410 electrically connected to the superconducting components is relatively large. Thus, in the second state during steady-state operation, the current conduction and the thermal conduction are reduced to an acceptable value. To aid in understanding, in the second state during steady-state operation, the current conduction and the thermal conduction are reduced to an acceptable level. To aid in understanding, in the second state during steady-state operation, the current conduction and the thermal conduction are two orders of magnitude lower than the current conduction and the thermal conduction of the device 300 described above. Beneficially, this reduces the heat loss from the cryogenic chamber 402. As will be appreciated, the device 400 allows for electrical connection between an external electrical device (such as a power source) at 300K and a superconducting component (such as a magnet of an MRI device or system) maintained at 40K, improving electrical and thermal properties compared to known connections.

[0042]

[0048] Beneficially, the relatively low electrical conductivity of the second state promotes a sort of self-cleaning. In particular, ice formation on surfaces when the magnet is operating at steady state is not an uncommon problem. This occurs even in the substantial absence of moisture, as ice can form from nitrogen in the environment. In known devices, ice can form on the contact pads of electrical connections. Thus, a distinct advantage of the device 400 is the helical coil design. To this end, if ice forms between adjacent turns of adjacent helical coils (e.g., at the seam 508 of adjacent helical loops 506 in the exemplary embodiment described below) when the device 400 is in the second state during steady state operation, actuation to compress the device to the first state compresses the helical loops, reducing the conductive cross section at the location where the ice formed, as described below, but separating the turns of the coil (with some gap maintained) so that, electrically, the cross section of this turn corresponds to that of the second state (described below). This results in a relatively high electrical resistance and relatively high ohmic heating. When the device 400 is compressed to the first state, heat generated during conduction raises the temperature, melts the ice, and the gap between adjacent helical coils is again substantially zero (i.e., they are in contact with each other). Beneficially, in the present teachings, this cleaning step is performed by a controller outside the cryochamber, and therefore without compromising the seal of the cryochamber.

[0043]

[0049] 5 is a perspective view showing a cross-sectional area of ​​an apparatus 500 for making electrical connections in a cryogenic chamber in a first state according to an exemplary embodiment. Various aspects and details of the apparatus 500 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1-4 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0044]

[0050] The device 500 includes a plurality of helical loops 506. The device 500 provides electrical and thermal paths between a superconducting component and an electrical device. As with the devices described above, the device 500 is generally made of a flexible conductive material that is cut to provide seams 508 that allow the device 500 to either compress in the −z direction of the coordinate system of FIG. 5 or stretch in the +z direction of the coordinate system of FIG. 5 to an expanded state, as described below. As described above, when compressed, the seams 508 between adjacent helical loops 506 are relatively small. Thus, when compressed, adjacent helical loops 506 are in intimate contact, such that the device 500 exhibits a ring-like conductive cross-section. Specifically, the cross-sectional area of ​​the device 500 is π(r o 2 -r i 2 ), where r o is the outer diameter of the helical loop 506, and r i is the inner diameter of the helical loop 506. As noted above, in this first state, the electrical resistance provided by the device is lower compared to when the device is in the second state (when adjacent helical rings are physically separated). In particular, the electrical resistance and thermal resistance of the device 500 are reduced to acceptable levels. To aid in understanding, the electrical resistance and thermal resistance of the device 500 are two orders of magnitude lower than the electrical resistance and thermal conductivity of the device in the second state when the helical loop 506 is separated.

[0045]

[0051] In the first state, a continuous electrical path is provided from one end of the device 500 to the other, minimizing the effects of surface contamination. Specifically, when the mating surfaces of adjacent helical loops 506 are compressed, the compressed structure (turn) is not contaminated and electricity is conducted through the large compressed cross section and along the short compressed length. The short structure provided by the device 500, which has a large cross section compared to the expanded device, offers little thermal resistance. Furthermore, if the mating surfaces between adjacent helical loops 506 are contaminated with ice, heat will be generated locally in these areas due to the reduced cross section of conductivity. As this area of ​​the device 500 is heated by the flow of electrical current, the contaminants will evaporate (especially in a vacuum), leaving behind a clean conductive surface, as desired.

[0046]

[0052] Furthermore, the inter-turn pressure between adjacent helical loops 506 that results in electrical conductivity similar to a closed cross-section is much lower than the inter-turn pressure that results in thermal conduction similar to a closed cross-section, meaning that the cross-section of the compressed device 500 is nearly electrically uninterrupted, but thermally much smaller, compared to the device in the expanded state where the helical loops 506 are separated.

[0047]

[0053] 6 is a perspective view showing a cross-sectional area of ​​an apparatus 600 for making electrical connections in a cryogenic chamber in a first state according to an exemplary embodiment. Various aspects and details of the apparatus 600 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1-5 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0048]

[0054] The device 600 includes a plurality of helical loops 606. The device 500 provides electrical and thermal paths between the superconducting component and an electrical device. As with the devices described above, the device 600 is generally made of a flexible conductive material cut to provide seams 508 that can be stretched or expanded in the +z direction of the coordinate system of FIG. 6 or compressed in the −z direction of the coordinate system of FIG. 6 into a compressed state, as described above. As described above, when stretched, the seams 608 between adjacent helical loops 606 are relatively large. Thus, when stretched or expanded, adjacent helical loops 606 are stretched and the device 600 exhibits a rectangular conductive cross-section with area H×W, where H is the height of the helical loop 606 and W is the width of the helical loop 606. In particular, when H=W, the device exhibits a square conductive cross-section. As described above, in this second state, the electrical resistance provided by the device is higher compared to when the device is in the first state (when adjacent helical rings are physically separated). In particular, the electrical resistance and thermal resistance of device 600 is increased relative to device 500. To aid in understanding, the electrical resistance and thermal resistance of device 600 are two orders of magnitude greater than the electrical resistance and thermal conductivity of device 500 in the first state where the helical coils are separated.

[0049]

[0055] In particular, during periods when no current needs to be passed through device 600, device 600 is uncompressed and adjacent helical loops 606 are separated (i.e., seams 608 are larger in the +z direction of the coordinate system of FIG. 6). In this second state, heat transfer from one end of device 600 to the other must occur through a relatively small H×W cross-section and along a large uncompressed length compared to compressed device 500. Such a relatively long structure with a small cross-sectional area provides poor thermal transfer compared to compressed device 500.

[0050]

[0056] Additionally, heat radiated through the open space at seam 608 between adjacent helical loops 606 is reduced compared to compressed device 500. This results in a smaller temperature difference between adjacent helical loops 606 compared to device 500. Additionally, when device 600 is used in a vacuum, there is no convective heat transfer across seam 608. Thus, in this second state, heat loss through device 600 is lower compared to device 500 where helical loops 506 are compressed and in contact with each other.

[0051]

[0057] 7 is a conceptual diagram illustrating compressive and expansive forces (F) applied by an actuator to compress and elongate or expand an apparatus 700 for making electrical connections in a cryogenic chamber from a second state to a first state. Various aspects and details of the apparatus 700 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1-6 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0052]

[0058] As shown in FIG. 7, an actuator (such as actuator 304, 404) applies a force that compresses device 700 (i.e., a force in the −z direction according to the coordinate system shown in FIG. 7) and expands or stretches device 700 (i.e., a force in the +z direction according to the coordinate system shown in FIG. 7). As described above, when compressed by an actuator, device 700 is in a first state having a lower electrical resistance and a higher thermal conductivity compared to when device 700 is stretched. Similarly, when stretched by an actuator, device 700 is in a second state having a higher electrical resistance and a lower thermal conductivity compared to when device 700 is compressed. As described above, the electrical resistance and thermal conductivity of device 700 in the first state are two orders of magnitude lower than the electrical resistance and thermal conductivity of device 700 in the second state.

[0053]

[0059] 8 is a flow chart of a method of providing electrical current to a superconductor component in a cryogenic chamber, according to an exemplary embodiment. Various aspects and details of method 800 are similar or identical to those described in connection with the exemplary embodiment of FIGS. 1-7 and will not be repeated so as not to obscure the description of this exemplary embodiment.

[0054]

[0060] The method includes, in step 801, providing an apparatus including a coil including a plurality of helical loops.

[0055]

[0061] The method includes compressing the coil to a first state at step 802. In the first state, the device has a first electrical resistance and a first thermal conductivity.

[0056]

[0062] The method expands the device to a second state at step 803. In the second state, the device has a second electrical resistance and a second thermal conductivity.

[0057]

[0063] Methods, systems, and components for reducing heat loss and providing power across an interface between a relatively low temperature environment (such as a cryogenic chamber) and a relatively high temperature environment (such as room temperature) have been described with reference to several exemplary embodiments, the terms used being understood to be terms of description and illustration, rather than terms of limitation. Changes may be made in their aspects within the scope of the appended claims, as currently presented and as amended, without departing from the scope and spirit of the optimization of interventional procedures. Although the development of adaptive predictive analytics has been described with reference to specific means, materials, and embodiments, it is not intended that the development of adaptive predictive analytics be limited to the details disclosed. Rather, the development of adaptive predictive analytics extends to all functionally equivalent structures, methods, and uses as set forth in the appended claims.

[0058]

[0064] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of various embodiments. The illustrations do not completely describe all elements and features of the disclosure described herein. Many other embodiments will be apparent to those skilled in the art upon review of the present disclosure. Other embodiments can be utilized and derived from the present disclosure, such as structural and logical substitutions and changes can be made without departing from the scope of the present disclosure. Moreover, the illustrations are merely representative and may not be to scale. Certain proportions in the illustrations may be exaggerated and other proportions may be minimized. Thus, the present disclosure and the figures should be considered illustrative and not restrictive.

[0059]

[0065] Although specific embodiments have been illustrated and described herein, it should be understood that subsequent arrangements designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. The present disclosure is intended to cover any and all subsequent adaptations or variations of the various embodiments. Combinations of the above embodiments with other embodiments not specifically described herein will be apparent to those of skill in the art upon review of the description.

[0060]

[0066] This Abstract of the Disclosure is provided for purposes of compliance with 37 C.FR §1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all features of any of the disclosed embodiments. Accordingly, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separate claimed subject matter.

[0061]

[0067] The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in the present disclosure. Therefore, the above disclosed subject matter is considered to be illustrative and not restrictive. Moreover, the appended claims are intended to cover all such modifications, enhancements, and other implementations that fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent permitted by law, the scope of the present disclosure shall be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be limited or restricted by the foregoing detailed description.

Claims

1. 1. An apparatus for electrically connecting a superconducting component located within a cryogenic chamber to an electrical device located outside the cryogenic chamber, the apparatus comprising: a coil providing an electrical path from the external electrical device to the superconducting component, the coil including a plurality of helical loops and located within the cryogenic chamber; an actuator for compressing and expanding the coil between a first state and a second state; Including, 1. An apparatus, wherein in the first state, the coil has a first electrical resistance and a first thermal conductivity, and in the second state, the coil has a second electrical resistance and a second thermal conductivity; The apparatus, wherein the actuator includes a linear motor.

2. The apparatus of claim 1 , wherein the first electrical resistance is less than the second electrical resistance.

3. The apparatus of claim 1 , wherein the first thermal conductivity is greater than the second thermal conductivity.

4. 10. The device of claim 1, wherein the device has a first cross-sectional area in the first state and a second cross-sectional area in the second state, the second cross-sectional area being smaller than the first cross-sectional area.

5. 5. The device of claim 4, wherein when the device is in the first state, the helical loops are compressed relative to one another and the first cross-sectional area is the area of ​​a ring.

6. 5. The device of claim 4, wherein when the device is in the second state, the helical loops separate from one another and the second cross-sectional area is a rectangular area.

7. 6. The device of claim 5, wherein a current of a first magnitude is passed through the device when the device is in the first state.

8. 8. The device of claim 7, wherein substantially no current flows through the device when the device is in the second state.

9. 1. A method of providing an electric current to a superconductor component located within a cryogenic chamber, the method comprising: providing an apparatus including a coil providing an electrical path from an electrical device to the cryogenic chamber to the superconductor component, the coil including a plurality of helical loops; compressing the coil to a first state, wherein in the first state the coil has a first electrical resistance and a first thermal conductivity; expanding the coil to a second state, wherein in the second state the coil has a second electrical resistance and a second thermal conductivity; Including, The method wherein the compression and expansion are performed by a linear motor.

10. The method of claim 9 , wherein the first electrical resistance is less than the second electrical resistance.

11. The method of claim 9 , wherein the first thermal conductivity is greater than the second thermal conductivity.

12. 10. The method of claim 9, wherein the device has a first cross-sectional area in the first state and a second cross-sectional area in the second state, the second cross-sectional area being smaller than the first cross-sectional area.

13. 13. The method of claim 12, wherein when the device is in the first state, the helical loops are compressed relative to one another and the first cross-sectional area is the area of ​​a ring.

14. 13. The method of claim 12, wherein when the device is in the second state, the helical loops separate from one another and the second cross-sectional area is a rectangular area.

15. a magnet system including a superconducting magnet located within a cryogenic chamber; An apparatus according to any one of claims 1 to 8; 1. A magnetic resonance imaging (MRI) system comprising:

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