System and method for detecting superconducting state transitions

Abstract

A system and method for detecting the superconducting state of a superconducting magnet used in magnetic resonance imaging (MRI) are disclosed. The system includes a sensor (208) having a magnet (230) capable of being positioned near one or more superconducting coil elements (204) of the superconducting magnet. The sensor is configured to switch between a first state and a second state based on a repulsive force generated between the magnet and the one or more superconducting coil elements, wherein the second state indicates that the one or more superconducting coil elements have reached a superconducting state, and wherein the first state indicates that the one or more superconducting coil elements have not yet reached the superconducting state. The output of the sensor can control the operation of a continuous current switch (206) and the connection or disconnection of a power supply (210) associated with the superconducting magnet.

Description

Background Technology

[0001] Magnetic resonance imaging (MRI) systems include superconducting magnets used to align and realign hydrogen nuclei (protons) within water molecules in the body being imaged. A strong first magnetic field is applied, causing the proton "spins" of the hydrogen nuclei to align, which can then be systematically realigned by applying a second magnetic field. MRI systems may include radio frequency (RF) coils to selectively apply a B1 magnetic field during the transmission phase. During the reception phase, the hydrogen nuclei return to their original positions (i.e., their positions before the selective application of the B1 magnetic field) and emit a weak RF signal, which can be picked up and used to generate an image. MRI systems typically also include a continuous current switch (PCS). The PCS is mounted in parallel with the superconducting magnet in the circuit, allowing a stable magnetic field to be maintained for extended periods.

[0002] Superconductivity is typically defined as a state where a material exhibits zero resistance at temperatures below a critical temperature threshold, where effects such as the escape of a magnetic field from the material occur. Because the PCS (polyconducting magnet) has resistance, the superconducting magnet is powered by direct current (DC) supplied by a power source. For example, a typical power source can provide 500 amperes of DC current. The PCS then switches to a state of short-circuiting with the DC power source (i.e., exhibiting low impedance) by reverting to the superconducting state, allowing a stable magnetic field to be maintained.

[0003] In conventional MRI systems, the superconducting windings (coils) of the superconducting magnet are typically composed of superconducting fibers embedded in a copper matrix and immersed in liquid helium to keep the superconducting windings (coils) below their critical temperature. In this previous generation, the PCS (polyconducting conductor) was heated above the critical temperature of the superconducting material used in the PCS, so that the PCS exhibited resistance when the superconducting windings (coils) of the superconducting magnet were powered by direct current. Typically, the critical temperature of the PCS is in the range of 6 to 9 Kelvin. In conventional MRI systems, the PCS is also immersed in liquid helium, which allows it to rapidly return to a superconducting state when the heater is turned off.

[0004] A novel "sealed" MRI system has been developed in which the propellant core (PCS) is not immersed in liquid helium. In this system, a sealed cooling system is filled with helium gas at elevated temperatures. The PCS is cooled by an external cooling system, which requires a significantly longer time before an MRI scan can be performed. Furthermore, the cooling time of the PCS may vary based on manufacturing differences in the superconducting magnet and the external cooling system. While it is possible to determine whether the PCS is in a superconducting or resistive state by measuring its temperature, sensors for accurately measuring cryogenic (extremely low) temperatures are expensive and prone to inaccuracies, for example, due to temperature gradients across the PCS.

[0005] Figure 1The illustration shows an MRI system 100 with a known circuit layout of a known MRI system. Figure 1 In this MRI system 100, a magnet system 102 is included, comprising a superconducting magnet coil 104 and a circuit control unit (PCS) 106, the PCS 106 including a switch 107 (main PCS switch). The superconducting magnet coil 104 in the circuit of the MRI system 100 can represent the coil in the aforementioned known MRI systems. A power supply 110 supplies current to the PCS 106 in the circuit. When the power supply supplies current to the PCS 106, the PCS is considered to be in an open circuit state. When the coil is in a superconducting state, the PCS 106 is in a closed circuit state, and the magnet system is in a continuous state. When the PCS 106 exhibits resistance, a significant voltage is generated; however, when the PCS 106 is in a superconducting state, no significant voltage is generated.

[0006] Figure 1 Previous generations of superconducting magnet systems in known MRI systems could not measure or directly determine the superconducting state of the superconducting magnet system. In these systems, the one or more superconducting coil elements 104 and PCS 106 of the superconducting magnet were immersed in a helium bath, and the open-circuit resistance of PCS 106 was likely on the order of 10 to 100 ohms. When ramping up (or powering) a previous generation of superconducting magnets, a voltage of approximately 6 volts was applied, and the current in the superconducting magnet followed the formula V=L. The relationship di / dt increases, where V is the voltage, L is the inductance, and di / dt is the rate of change of inductance with time. When powering the superconducting magnet, some direct current flows through PCS 106. When PCS 106 reaches the required current, the voltage across PCS 106 begins to drop because the current is redistributed to one or more superconducting coil elements 104 of the superconducting magnet, which have zero resistance in the superconducting state.

[0007] A newer MRI system has been developed in which the PCS is not immersed in liquid helium, and cooling the PCS via an external cooling system requires a significantly longer time before MRI can be performed. Furthermore, the cooling time of the PCS can vary based on manufacturing differences in the superconducting magnet and the external cooling system. Once the conductor is assumed to have returned to a superconducting state, the magnet system attempts to apply current to the PCS. If the PCS has not yet returned to a superconducting state, the switch will fail to close, and the magnet will not be able to enter a sustained state. If the switch fails to close, the magnet will not be able to complete the power supply and will return to a non-magnetic field state. The inability to perform ramp-up results in delays before subsequent ramp-up attempts, which is particularly problematic when attempting to deliver the magnet system to the customer at the installation site. Therefore, new methods are needed to determine the superconducting state of a superconducting magnet system with a reasonable level of accuracy. Summary of the Invention

[0008] According to one aspect of this disclosure, a system for detecting the superconducting state of a superconducting magnet used in a magnetic resonance imaging (MRI) system includes: a superconducting magnet formed of one or more superconducting coil elements; a continuous current switch coupled to the superconducting magnet; and a sensor including a magnet, wherein the sensor is coupled to the continuous current switch and an associated power source, wherein in a first state, the sensor electrically couples the associated power source to the superconducting magnet; and in a second state, the sensor electrically disconnects the associated power source from the superconducting magnet, wherein the sensor switches between the first and second states based on a repulsive electromagnetic force generated between the magnet and the superconducting coil elements, for example, the sensor can be used to detect a transition of the superconducting coil elements from the first state to the second state (e.g., from a resistive state to a superconducting state); and from the second state to the first state (e.g., from a superconducting state to a resistive state).

[0009] According to another aspect of this disclosure, a method for detecting the superconducting state of a superconducting magnet used in a magnetic resonance imaging (MRI) system includes: providing a continuous current switch; providing a superconducting magnet formed of one or more superconducting coil elements; coupling a sensor to the continuous current switch and an associated power supply, such that the sensor switches between a first state and a second state: in the first state, the sensor electrically couples the associated power supply to the superconducting magnet; in the second state, the sensor electrically disconnects the associated power supply from the superconducting magnet, wherein the sensor switches between the first state and the second state based on the superconducting state of the superconducting coil elements.

[0010] The system and method actively switch the sensor between a first state and a second state by utilizing the repulsive electromagnetic force generated between the sensor and the one or more superconducting coil elements. The repulsive electromagnetic force is generated by the Meissner effect interaction between the sensor and the one or more superconducting coil elements. Attached Figure Description

[0011] The exemplary embodiments can be best understood by reading in conjunction with the accompanying drawings, based on the following detailed description. It should be emphasized that the various features are not necessarily drawn to scale. In fact, dimensions may be increased or decreased arbitrarily for clarity of discussion. Where applicable and practicable, the same reference numerals refer to the same elements.

[0012] Figure 1 The illustration shows the conventional superconducting configuration of a traditional MRI system.

[0013] Figure 2 The diagram illustrates a circuit of an MRI system for superconducting state detection with a superconducting magnet system, according to a representative embodiment.

[0014] Figures 3A-3B An exemplary sensor for an MRI system suitable for detecting the superconducting state of a superconducting magnet system, according to a representative embodiment, is illustrated.

[0015] Figures 4A-4B The illustration shows another exemplary sensor for an MRI system suitable for detecting the superconducting state of a superconducting magnet system, according to a representative embodiment.

[0016] Figure 5 The illustration shows yet another exemplary sensor of an MRI system suitable for detecting the superconducting state of a superconducting magnet system, according to a representative embodiment.

[0017] Figure 6 An exemplary method for detecting the superconducting state of a superconducting magnet, according to a representative embodiment, is illustrated. Detailed Implementation

[0018] The following detailed description is for illustrative purposes only and not for limiting purposes. Representative embodiments disclose specific details to provide a thorough understanding of embodiments according to these teachings. Descriptions of known systems, apparatuses, materials, methods of operation, and methods of manufacture may be omitted to avoid obscuring the description of representative embodiments. Nevertheless, systems, apparatuses, materials, and methods that are within the scope of these teachings and are applicable to those skilled in the art can be used according to representative embodiments. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The defined terms have meanings beyond their scientific and technical meanings as commonly understood and accepted in the art of this teaching.

[0019] It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another. Therefore, without departing from the teachings of the inventive concept, the first element or component discussed below may also be referred to as the second element or component.

[0020] As used in the specification and claims, the singular forms of the terms “a,” “an,” and “the” are intended to include both the singular and plural forms, unless the context clearly specifies otherwise. Additionally, when used herein, the terms “comprising,” “including,” “containing,” and / or “comprising” and / or similar terms specify the presence of the recited 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. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Unless otherwise stated, when an element or component is said to be “connected to,” “coupled to,” or “adjacent to” another element or component, it will be understood that the element or component can be directly connected to or coupled to the other element or component, or that there may be intermediate elements or components. That is, these and similar terms include cases where one or more intermediate elements or components may be used to connect two elements or components. However, when an element or component is referred to as being “directly connected” to another element or component, this only includes cases where two elements or components are connected to each other without any intermediate or intervening elements or components.

[0022] As described herein, various aspects of the present invention relate to systems and methods for sensing the transition of a superconducting magnet system from a resistive (normal) state to a superconducting onset state and vice versa. More broadly, various aspects of the present invention relate to systems and methods for determining the superconducting state of a superconducting magnet and / or one or more superconducting coil elements in a substantially real-time manner at any given time. The present invention is described as being for hermetically sealed MRI magnets, where the crossing of transition temperatures and the superconducting onset state have a more critical impact on magnet performance than in conventional MR magnets. However, those skilled in the art will readily understand that the present invention is applicable to any superconducting system in which the determination of the superconducting state of the system is required. Superconducting switch state detection is used for superconducting magnet control, providing the ability to accurately determine the specific time when the PCS is closed or about to close, and / or the time when the superconducting magnet transitions from a non-superconducting state to a superconducting state or from a superconducting state to a non-superconducting state, and eliminating the need to incorporate other detection mechanisms into the MRI system, which may require expensive components (e.g., expensive temperature sensors, such as ruthenium oxide sensors). The superconducting switch state detection described in this paper provides determinism based on the actual superconducting state of the superconducting magnet system rather than on predictions, which may be based on average values ​​of similar superconducting magnets without taking into account structural variables or performance degradation due to aging or operating conditions.

[0023] Figure 2 The illustration shows a system 200 for detecting the superconducting state of a superconducting magnet system 202 according to various aspects of the present invention. Figure 2In a representative embodiment, a PCS 206, including a PCS switch 207, is connected to one or more superconducting coil elements 204 of a superconducting magnet. System 200 includes a superconducting magnet formed of one or more superconducting coil elements 204. The superconducting magnet also includes a PCS 206 coupled to the superconducting coil elements 204 in a parallel arrangement. In one embodiment, a sensor 208 including a magnet 230 is coupled to the PCS. In another embodiment, the sensor 208 including the magnet 230 is coupled between the PCS 206 and an associated power source 210 in a parallel arrangement. In a first state (non-superconducting state), the sensor 208 electrically couples the associated power source 210 to the superconducting coil element 204; in a second state (superconducting state), the sensor 208 electrically disconnects the associated power source 210 from the superconducting coil element 204, such that the one or more superconducting coil elements 204 and PCS 206 are in a continuous mode.

[0024] Sensor 208 switches between a first state and a second state based on the superconducting state of superconducting coil element 204. Various aspects of the invention utilize the Meissner effect interaction between the magnet 230 of sensor 208 and the one or more superconducting coil elements 204. Typically, when the superconducting coil element 204 is in a superconducting state, a repulsive electromagnetic force is generated between sensor 208, which incorporates a magnet (e.g., a permanent magnet, an electromagnet), and the one or more superconducting coil elements 204. When the superconducting coil element 204 is in a non-superconducting state, the repulsive electromagnetic force is absent or negligible. Therefore, sensor 208 provides an accurate indication of the superconducting state of the superconducting magnet 204 and / or the one or more superconducting coil elements 204 at any given time. The repulsive electromagnetic force exerted between sensor 208 and the superconducting magnet and / or the one or more superconducting coil elements 204 is greater in the second state (superconducting state) than in the first state (non-superconducting state), causing the sensor to sense additional forces and / or displacement of the magnet position within sensor 208.

[0025] like Figure 2As shown, the system may include a controller 212 operatively coupled to sensor 208. Controller 212 may be mounted in a housing connected to the exterior of the superconducting magnet cryostat container. As described in more detail below, controller 212 is configured to receive an output signal 214 generated from sensor 208. Output signal 214 indicates the superconducting state of the superconducting magnet and / or one or more superconducting coil elements 204. The controller 212 may be positioned based on its characteristics. For example, when controller 212 includes analog circuitry that directly measures the characteristics at both ends of the PCS or receives the output from sensor 208, controller 212 may include one or more components in direct contact with PCS 206 and / or sensor 208, and one or more other components located in a housing connected to the exterior of the cryostat container. In the embodiments described herein, the electronics of controller 212 may not actually be within the cryostat container, and in some embodiments, controller 212 may be arranged separately from the superconducting magnet system 202.

[0026] The output signal 214 generated from sensor 208 can be any type of signal, which provides controller 212 with information about the superconducting state of one or more superconducting coil elements 204. Controller 212 is communicatively coupled to the MRI system in such a way that the MRI system can utilize the information provided to controller 212 by output signal 214 to allow the MRI system to tilt the superconducting magnet up or down based on desired operation, and / or perform an MRI examination on the subject while the superconducting magnet is in a superconducting state.

[0027] PCS 206 and sensor 208 are illustrated as being connected in parallel between power supply 210 and superconducting magnet and / or one or more superconducting coil elements 204. Those skilled in the art will understand that other embodiments or one or more intermediate components may be included in this and other configurations, and all such embodiments should be considered within the scope of this disclosure.

[0028] Power supply 210 primarily supplies DC power to the superconducting magnet system 202 until one or more superconducting coil elements 204 are in a superconducting state. After the superconducting magnet system 202 is powered and in a superconducting state, the heater is disconnected from the PCS and thus cooled to the superconducting state temperature, switching to continuous mode. At this point, sensor 208 changes from a first state to a second state based on the one or more superconducting coil elements becoming superconducting. In the second state (superconducting state), sensor 208 outputs an output signal 214, which can be used as an input to controller 212 (or other components) to determine when to perform an action on system 200. For example, the controller can use output signal 214 to electrically disconnect the associated power supply 210 from the superconducting magnet system 202 and / or superconducting coil elements 204. Similarly, controller 212 can also use output signal 214 to electrically connect the associated power supply 210 to the superconducting magnet system 202 and / or superconducting coil elements 204 in a resistive state. When the superconducting magnet system 202 is in a superconducting state, it can be used to perform MRI examinations on objects.

[0029] exist Figure 2 and most based on Figure 2 In some embodiments, the MRI system 200, including the magnet system 202, may employ a so-called "liquid helium-free" superconducting magnet as the superconducting magnet, which includes the one or more superconducting coil elements 204. In this document, such a "liquid helium-free" superconducting magnet system may be referred to as a sealed superconducting magnet system with a hermetically sealed superconducting magnet. The term "hermetically sealed" refers to the fact that the superconducting magnet system is not immersed in a refrigerant. Compared to previously unhermetically sealed systems that used relatively large volumes of refrigerant material (e.g., 1000 liters of liquid helium), the sealed superconducting magnets in such hermetically sealed superconducting magnet systems typically have a smaller volume of refrigerant material (e.g., less than 10 liters of liquid helium). As mentioned above, the PCS 206 used in a hermetically sealed system requires a longer time to shut off (become continuous), for example, approximately one hour.

[0030] like Figure 2 As shown, PCS 206 is connected across one or more superconducting coil elements 204 of the superconducting magnet system 202. Power supply 210 provides current to PCS 206 in a parallel circuit. When power supply provides current to PCS 206, PCS is in an open-circuit state (and PCS 206 is in a resistive state, also referred to as the first state in this specification). When one or more superconducting coil elements 204 and / or the magnet system 202 are in a superconducting state, PCS switch 206 is in a closed state, and the superconducting magnet system 202 is in a continuous state, referred to as the second state in this specification.

[0031] Sensor 208 is coupled to PCS 206 and an associated power supply 210, wherein, in a first state, sensor 208 electrically couples the associated power supply 210 to the superconducting magnet and / or the one or more superconducting coil elements 204. In a second state, sensor 208 electrically disconnects the associated power supply 210 from the superconducting magnet and / or the one or more superconducting coil elements 204. Sensor 208 switches between the first and second states based on the superconducting state of the superconducting coil element 204. Sensor 208 can also be configured to switch from the second state to the first state based on the superconducting state of the superconducting coil element 204.

[0032] As discussed in more detail in the following embodiments, sensor 208 includes one or more magnets in contact with or close proximity to the one or more superconducting coil elements 204. In a non-superconducting state, no repulsive electromagnetic force, or only a negligible one, is generated between the permanent magnet of sensor 208 and the one or more superconducting coil elements 204. However, this changes when the one or more superconducting coil elements 204 become superconducting. When the one or more superconducting coil elements 204 become superconducting, a repulsive electromagnetic force is generated between the magnet of the sensor and the one or more superconducting elements, causing the sensor to switch from a first state to a second state. This repulsive electromagnetic force is generated by the Meissner effect interaction between the permanent magnet of sensor 208 and the one or more superconducting elements 206.

[0033] Sensor 208 is also configured to operate when one or more superconducting coil elements 204 transition from a superconducting state to a non-superconducting position. When one or more superconducting coil elements 204 transition from a superconducting state to a non-superconducting position, the repulsive electromagnetic force between the permanent magnet of sensor 208 and the one or more coil elements 204 disappears, and sensor 208 is configured to generate an output signal to controller 212 indicating the non-conducting state of the one or more coil elements 204. Therefore, when the superconducting coil element 204 no longer exhibits superconductivity, sensor 208 switches from a second state to a first state. One advantage of the sensor 208 and various embodiments described herein is that the superconducting state of the superconducting magnet and / or one or more superconducting coil elements can be detected substantially in real time at any given moment.

[0034] Figure 3A and 3BAn exemplary system 300 including a sensor 308 according to various aspects of the present invention is illustrated. The sensor 308 includes a force transmission element 320 having a first end 322 coupled to a magnet 330 and a second end 324 coupled to a piezoelectric component 332. As discussed in more detail below, the force transmission element 320 may be rigid or elastic, depending on the design implementation. The piezoelectric component 322 is configured to output an output signal 214 to a controller 212 or another component of the MRI system 200 via one or more measuring leads 326. The output signal 214 may represent an electromagnetic force generated between the permanent magnet 330 and the superconducting magnet system 202 and / or the one or more superconducting coil elements 204 and transmitted to the piezoelectric component 332 via the force transmission element 320. In another embodiment, the output signal may represent the position of the permanent magnet 330 relative to the one or more superconducting coil elements 204 and / or the piezoelectric component 332. In either case, the output signal is coupled as an input to the controller 212 and is used to determine the superconducting state of one or more superconducting coil elements 204.

[0035] Figure 3A An embodiment of the invention is illustrated, wherein the superconducting magnet system 202 and / or the one or more superconducting coil elements 204 are in a resistive state (e.g., a non-superconducting state). As shown, a magnet 330 is close to or in contact with the superconducting magnet or the one or more superconducting coil elements 204. In this state, no repulsive force is typically generated between the magnet 330 and the one or more superconducting coil elements 204. Therefore, the force applied to the piezoelectric member 332 by the force transmission element 320 is less than the force when the magnet system 202 and / or the one or more superconducting coil elements 204 are in a superconducting state.

[0036] Figure 3B An embodiment of the invention is illustrated, wherein the superconducting magnet system 202 and / or one or more superconducting coil elements 204 are in a superconducting state. When the magnet system 202 and / or one or more superconducting coil elements 204 are in a superconducting state, a repulsive electromagnetic force is generated between the magnet 330 of the sensor 308 and the superconducting magnet system 202 and / or the one or more superconducting coil elements 204. The repulsive force is generated by the Meissner effect interaction between the magnet 330 of the sensor 308 and the superconducting magnet system 202 and / or the one or more superconducting coil elements 204. In the illustrated embodiment, the magnet 330 is displaced from a position close to or in contact with the magnet system 202 to another distance, said distance being farther from the one or more superconducting coil elements 204. This distance can be proportional to the repulsive force exerted between the magnet 330 of the sensor 308 and the one or more superconducting coil elements 204.

[0037] In another embodiment, the magnet 330 may remain substantially in the same position (e.g., the force transmission element 320 is rigid), but the repulsive force between the magnet 330 of the sensor 308, as measured by the piezoelectric component 332, and the superconducting magnet system 202 and / or one or more superconducting coil elements 204 will increase based on the superconducting state of the superconducting magnet system 202 and / or one or more superconducting coil elements 204.

[0038] Figures 3A-3B The illustration shows the force transmission member 320 as a plunger or spring device. It should be noted that, for ease of demonstration, the sensor device and one or more conductive coil elements are not shown to scale. The purpose is to make the sensor and its various components (e.g., force transmission member 320, such as a spring or plunger, permanent magnet, and piezoelectric element) compact, requiring the shortest possible travel distance to achieve a measurable signal. In this device, when a magnetic field is discharged, the magnet acts on the solid force transmission member (e.g., plunger or spring), which pushes the center of the piezoelectric element 332. This element then converts the applied force into a voltage larger than the steady-state voltage amplitude across the element, serving as an input to a controller or other electronic device to generate an output signal indicating the superconducting state of the superconducting magnet and / or one or more superconducting coil elements 204.

[0039] Figures 3A-3B An optional housing 340 for sensor 308 is illustrated. Those skilled in the art will readily understand that housing 340 can be of any size or shape. In one embodiment, housing 340 is configured to at least partially enclose force-transmitting member 320, force-transmitting element, and / or piezoelectric component 332. Housing may also be configured to at least partially enclose portions of permanent magnet 330 and the one or more superconducting coil elements 204.

[0040] Figures 4A-4B Another exemplary embodiment 400 according to various aspects of the present invention is illustrated. The sensor 408 also includes a force transmission element 420 having a first end 422 coupled to a lever device 440 and a second end 424 coupled to a piezoelectric member 432. The piezoelectric member 432 is configured to output an output signal representing an electromagnetic force generated between the magnet 430 and the lever device 440 through the force transmission element 420. Figures 4A-4BIn this embodiment, the force transmission element 420 is illustrated as a spring. In this embodiment (spring-spring-lever device), the sensor functions similarly to a spring scale, where the repulsion between the magnet 430 and the one or more superconducting coil elements 204 pushes the lever 440 downwards, which in turn pulls the force transmission element 432 (e.g., the spring), thereby applying an additional force to the piezoelectric component 432. The piezoelectric component 432 outputs an output signal commensurate with the applied force, which can serve as an input to the controller 212 for determining the superconducting state of the superconducting magnet system 202 and / or the one or more superconducting coil elements 204. Therefore, the sensor 408 is configured to switch from a first state (e.g., a resistive state) to a second state (e.g., a superconducting state) when the superconducting coil element 204 is in a superconducting state. When the superconducting coil element 204 is no longer in a superconducting state, the sensor 408 also switches from the second state to the first state.

[0041] Figures 4A-4B An optional housing 450 for sensor 408 is illustrated. Those skilled in the art will readily understand that housing 450 can be of any size or shape. In one embodiment, housing 450 is configured to at least partially enclose force-transmitting element 420, lever device 440, and / or piezoelectric component 432. Housing 450 may also be configured to at least partially enclose portion of magnet 430 and the one or more superconducting coil elements 204.

[0042] Figure 5 Another exemplary embodiment according to various aspects of the present invention is illustrated. Figure 5 The illustrated sensor embodiment resembles a reed switch. In this embodiment, when the superconducting magnet system 202 and / or the one or more superconducting coil elements 204 are in a normal state (e.g., a resistive state), the force transmission element 520 (illustrated as a spring) keeps the magnet 530 and the electrical contacts (510 and 542) separated. Once the Meissner effect causes the magnet 530 to be pushed upward (repelled) by the one or more superconducting coil elements 204, the contacts (510 and 542) will close, thereby engaging the contacts (510 and 542). In this embodiment, a low-power external current source can be used to detect the state of the switch, which will generate an output signal indicating the superconducting state of the superconducting magnet system 202 and / or the one or more superconducting coil elements 204, which is output to the controller 212. For example, the output signal can be binary, or it can be an analog or digital signal proportional to the force and / or position of the system components. Thus, when the superconducting coil element 204 is in a superconducting state, the sensor is configured to switch from a first state (e.g., a resistive state) to a second state (e.g., a superconducting state).

[0043] When the superconducting coil element 204 changes to a non-superconducting state, the repulsive force between the magnet 530 and the superconducting coil element 204 weakens, and the force transmission element 520 extends, thereby breaking the circuit between contacts 510 and 542. An output signal is generated indicating that the superconducting magnet system 202 and / or one or more superconducting coil elements 204 are in a non-superconducting state, and this output signal is used as the input to the controller 212. Thus, based on the fact that the superconducting coil element 204 no longer possesses superconductivity, the sensor switches from a second state to a first state.

[0044] In this embodiment, the sensor includes one or more first electrical contacts 510 coupled to at least a portion of a permanent magnet 530. A force-transmitting element 520 includes a first end mechanically coupled to the permanent magnet 530 and a second end mechanically coupled to a housing 540. The housing 540 may include at least one or more second electrical contacts 542 configured to electrically couple with one or more first electrical contacts 510 when the one or more superconducting coil elements are in a superconducting state. That is, the repulsive force applied between the sensor's magnet 530 and the superconducting magnet system 202 and / or the one or more superconducting coil elements 204 forces the electrical contacts 510 into electrical contact 542. When the electrical contacts 542 directly or indirectly (through another conductive component) engage with the electrical contacts 510 to form a circuit, an output signal is generated indicating that the magnet system 202 and / or the one or more superconducting coil elements 204 are in a superconducting state. When the circuit formed by the coupling of electrical contacts 510 and 542 is in or becomes an open circuit, an output signal is generated indicating that the magnet system 202 and / or the one or more superconducting coil elements 204 are in a non-superconducting state. The output signal can be input to the controller 212 to determine the superconducting state and / or for use in the control system.

[0045] It will be readily understood by those skilled in the art that the housing 540 can be of any size or shape. In one embodiment, the housing 540 is configured to at least partially enclose the force transmission member 520 and the electrical contacts 510 and 542. Optionally, the housing is configured to at least partially enclose the permanent magnet 530 and is located at a portion of the one or more superconducting coil elements 204.

[0046] The various embodiments provided above identify various force transmission elements 320, 420, 520. Those skilled in the art will readily understand that the force transmission element can take many forms, such as a spring, a plunger, or any other material suitable for applying mechanical forces in a superconducting environment.

[0047] The various embodiments provided above identify magnets 330, 430, and 530. Magnets can take any form, size, and / or shape. In one embodiment, magnets 330, 430, and 530 can be permanent magnets. Permanent magnets are generally defined as materials whose magnetic field is generated by the material's own internal structure. In another embodiment, magnets 330, 430, and 530 can be electromagnets. Electromagnets are typically metal cores that become magnets by passing an electric current through a coil surrounding them. For example, a current can be applied to the electromagnet during the ramp-up of the magnet system to a superconducting state. When the superconducting state is reached, the current flowing to the electromagnet can be shut off. In another embodiment, a current can be continuously applied to the electromagnet, which would allow detection of the magnet system transitioning from a resistive state to a superconducting state, and from a superconducting state to a resistive state.

[0048] Those skilled in the art will readily understand that piezoelectric components 332, 432 can take many forms, such as pressure sensors, position sensors, transducers, Hall effect transducers, strain gauges, or any other piezoelectric component suitable for outputting an output signal that can be used to indicate the superconducting state of the superconducting magnet system 202 and / or the one or more superconducting coil elements 204.

[0049] exist Figure 2 In this design, controller 212 is shown closely adjacent to the one or more superconducting coil elements 204 and PCS 206. However, controller 212 may be provided separately from the circuitry, for example, when connected via a communication line carrying digital signals generated by an analog-to-digital converter near PCS 206. Furthermore, controller 212 may include a set of elements working together, such as a memory storing instructions and a processor (e.g., a microprocessor) executing those instructions to implement the processes described herein. Controller 212 may also be a processor or include a processor, such as an application-specific integrated circuit (ASIC), which can automatically perform logical functions without necessarily requiring software, for example, triggering a response based on analog detection of a voltage level reaching a threshold.

[0050] Controller 212 may include detection circuitry. The detection circuitry may include an ADC (Analog-to-Digital Controller), a processor, and memory. The ADC detects analog voltage readings from the PCS (e.g., PCS 206) and / or from any sensor embodiment of the invention illustrated in the figures, and converts the detected analog voltage readings from analog readings into digital values. The ADC outputs a digital signal with the digital value to the processor. The analog voltage readings are based on a variable voltage across the PCS and / or based on any sensor embodiment of the invention, which is determined by whether the superconducting magnet system 202 and / or one or more superconducting coil elements 204 are in a resistive state (non-superconducting state) or a superconducting state. The processor retrieves or receives software instructions from memory and executes these instructions to determine whether the superconducting magnet system 202 and / or one or more superconducting coil elements 204 are in a non-superconducting state or a superconducting state.

[0051] For controller 212, those skilled in the art will readily understand that logical operations are performed on digital data by a processor executing instructions from one or more memories. However, logical operations can also be performed via an application-specific integrated circuit (ASIC), which may include circuitry for generating output signals representing the superconducting state of the superconducting magnet system 202 and / or one or more superconducting coil elements 204.

[0052] Figure 6 The illustration depicts a process or method 600 for detecting the superconducting state of a superconducting magnet according to a representative embodiment. For example... Figure 2 As shown, the superconducting magnet includes: PCS 206, a sensor according to any embodiment of the invention, and one or more superconducting coil elements 204. An associated power supply is provided, which can be coupled to one or more components of the superconducting magnet. Figure 2 The diagram shows PCS 206, a sensor according to any embodiment of the invention, and the one or more superconducting coil elements 204 coupled in a parallel arrangement. The sensor according to any embodiment of the invention may be coupled between PCS 206 and an associated power supply 210 in a parallel arrangement. PCS 206 may be coupled between the sensor according to any embodiment of the invention and the one or more superconducting coil elements 204.

[0053] Figure 6 The process begins from the default state at S610, in Figure 6 In this embodiment, the default state is the resistive state (i.e., the non-superconducting state) when PCS 206 is disconnected. The default state S610 may be that PCS 206 is not cooled and therefore the temperature is above the critical temperature (e.g., the temperature required for the magnet system 202 and / or the one or more superconducting coil elements 204 to reach the superconducting state) and is in an open-circuit configuration.

[0054] At S620, Figure 6 The process shown includes starting the cooling system for the PCS 206. Figure 2 The cooling system is not shown in circuit 200, but S620 can be executed manually or automatically by the machine.

[0055] At S630, Figure 6 The illustrated process includes switching the sensor between a first state and a second state, in which the sensor electrically couples an associated power supply to a superconducting magnet; and in the second state, when the sensor detects that one or more superconducting coil elements 204 are in a superconducting state according to any embodiment of the invention, the sensor electrically disconnects the associated power supply from the superconducting magnet. As described above, this state detection is achieved when the sensor detects a repulsive electromagnetic force generated by the interaction between the sensor's permanent magnet and the one or more superconducting coil elements 204 according to any embodiment of the invention.

[0056] At S640, Figure 6 The illustrated process includes generating an output signal for output to controller 212, which the MRI system can use to indicate whether magnet system 202 is in a non-superconducting or superconducting state. When magnet system 202 is in a superconducting state, the MRI system can be used to image a patient. When magnet system 202 is in a non-superconducting state, the controller can be used to control a cooling system (not shown) to bring PCS 206 and / or one or more superconducting coils to a superconducting temperature.

[0057] In the S650, Figure 6 The process includes notifying the operator of the superconducting state of the output magnet system 202. The notification may be in the form of an audible signal, a visual signal (e.g., a light illuminating), and / or a data signal provided to a communication device or computer display to alert the operator to the superconducting state of the magnet system 202.

[0058] In the S660, Figure 6 The process shown ends with the execution of an MRI procedure. The MRI procedure can be executed based on confirmation that the magnet system 202 is in a superconducting state.

[0059] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of various embodiments. These illustrations are not intended to be a complete depiction of all elements and features of the disclosure described herein. Many other embodiments will likely be apparent to those skilled in the art after reviewing this disclosure. Other embodiments can be utilized and derived from this disclosure, allowing structural and logical substitutions and changes to be made without departing from the scope of this disclosure. Furthermore, these illustrations are representative only and may not be drawn to scale. Some scales in the illustrations may be enlarged, while others may be minimized. Therefore, this disclosure and the accompanying drawings should be considered illustrative rather than restrictive.

[0060] The term "invention" may be used independently and / or collectively for convenience only, but this does not imply that the scope of this application is intentionally limited to any particular invention or inventive concept. Furthermore, while specific embodiments have been illustrated and described herein, it should be understood that any subsequent arrangements designed to achieve the same or similar purpose may replace the specific embodiments shown. This disclosure is intended to cover any and all subsequent modifications or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art upon review of the specification.

[0061] The abstract of this disclosure provided conforms to 37 CFR § 1.72(b), and it should be understood at the time of submission that the abstract is not intended to interpret or limit the scope or meaning of the claims. Furthermore, in the foregoing detailed description, various features may be combined together or described in a single embodiment for the purpose of simplifying this disclosure. This disclosure should not be construed as reflecting an intention that the claimed embodiments require more features than expressly recited in each claim. Rather, as reflected in the following claims, the inventive subject matter may refer to fewer than all features of any of the disclosed embodiments. Therefore, the following claims are incorporated into the detailed specification, wherein each claim independently defines the claimed subject matter.

[0062] The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in this disclosure. Therefore, the subject matter disclosed above should be considered illustrative rather than restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments falling within the true spirit and scope of this disclosure. Accordingly, to the fullest extent permitted by law, the scope of this disclosure will be determined by the broadest permissible interpretation of the following claims and their equivalents, and should not be limited to or restricted to the foregoing detailed description.

Claims

1. A system for detecting the superconducting state of a superconducting magnet (202) used in a magnetic resonance imaging system, comprising: The sensor (208) includes a magnet (230) capable of being positioned near one or more superconducting coil elements (204) of the superconducting magnet; The sensor is configured to switch between a first state and a second state based on the repulsive force generated between the magnet and the one or more superconducting coil elements, wherein the second state indicates that the one or more superconducting coil elements have reached a superconducting state, and wherein the first state indicates that the one or more superconducting coil elements have not yet reached the superconducting state.

2. The system according to claim 1, wherein, The sensor is configured to switch between a second state and a first state when the repulsive electromagnetic force generated between the magnet of the sensor and the one or more superconducting coil elements disappears.

3. The system according to claim 1 or 2, wherein, The repulsive force is generated by the Meissner effect interaction between the magnet of the sensor and the one or more superconducting coil elements.

4. The system according to any one of claims 1 to 3, wherein, The sensor further includes a force transmission element (320) having a first end coupled to the magnet (330) and a second end coupled to a piezoelectric component (322), wherein the piezoelectric component is configured to output an output signal representing an electromagnetic force generated between the magnet and the one or more superconducting coil elements and transmitted by the force transmission element to the piezoelectric component.

5. The system according to any one of claims 1 to 3, wherein, The sensor also includes a force transmission element (420) having a first end coupled to a lever device (440) and a second end coupled to a piezoelectric component (432), wherein the piezoelectric component is configured to output an output signal representing an electromagnetic force generated by the magnet (430) between the magnet (430) and the one or more superconducting coil elements and transmitted by the lever device to the piezoelectric component via the force transmission element.

6. The system according to claim 4 or 5, further comprising a housing (340, 450), wherein, The housing is configured to at least partially accommodate at least one of the magnet and the force transmission element.

7. The system according to any one of claims 1 to 3, wherein, The sensor includes one or more first electrical contacts (510) coupled to at least a portion of the magnet (530), and a force transmission element (520) has a first end mechanically coupled to the magnet and a second end mechanically coupled to a housing (540), wherein the housing includes at least one or more second electrical contacts (542) configured to be electrically coupled to the one or more first electrical contacts when the superconducting coil element is in the superconducting state.

8. The system according to any one of claims 1 to 7, wherein, The magnet is selected from at least one of permanent magnets and electromagnets.

9. The system according to any one of claims 1 to 8, further comprising a controller (212) configured to receive an output signal from the sensor, wherein, The output signal represents the repulsive force generated between the magnet and the one or more superconducting coil elements.

10. The system according to any one of claims 1 to 9, further comprising: The superconducting magnet (202) includes the one or more superconducting coil elements (204); A continuous current switch (206) is coupled to the superconducting magnet, wherein the operation of the continuous current switch is based on whether the sensor is in the first state or the second state.

11. The system of claim 10, wherein the continuous switch and the superconducting magnet are connectable to an associated power source (210), wherein, The associated power supply to the superconducting magnet is connected and / or disconnected based on whether the sensor is in the first state or the second state.

12. A method for detecting the superconducting state of a superconducting magnet (202) used in a magnetic resonance imaging system, comprising: Position a sensor (208) containing a magnet (230) near one or more superconducting coil elements (204) of the superconducting magnet; Based on the repulsive force generated between the magnet and the one or more superconducting coil elements, the sensor switches between a first state and a second state, wherein the second state indicates that the one or more superconducting coil elements have reached a superconducting state, and wherein the first state indicates that the one or more superconducting coil elements have not yet reached the superconducting state.

13. The method of claim 12, comprising: When the repulsive electromagnetic force generated between the magnet of the sensor and the one or more superconducting coil elements disappears, the sensor switches between its second state and its first state.

14. The method according to claim 12 or 13, further comprising: Based on whether the sensor is in the first state or the second state, the continuous current switch (206) coupled to the superconducting magnet is operated.

15. The method of claim 14, comprising: Based on the output of the sensor in relation to the first state or the second state, the power supply (210) is coupled to and / or decoupled from the superconducting magnet.

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