MRI Emergency Quench Control via External Dissipation
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Solution Overview
Problem
Superconducting MRI magnets require costly and time-consuming quenching procedures during emergencies, which can cause mechanical damage and prolonged cooling times, as existing systems lack a reliable method to differentiate between immediate quenching and controlled ramp-down operations.
Innovation Solution
A magnetic resonance imaging system with a superconductive magnet and an emergency button, where distinct user actions (e.g., single vs. double pressing) control the magnet's state, allowing for either controlled energy dissipation to an external device or quenching, enabling rapid field removal without unnecessary heating or helium loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a quench button is activated during an emergency, then the magnetic field is rapidly removed, but the magnet conductors warm up and require significant extra time to cool down before the magnetic field can be ramped up again
Solution Approach 1:
The system dynamically adjusts the emergency response based on the state of the external dissipation device. When the dissipation device is available and operational, the system routes energy externally to avoid quenching. When the dissipation device is unavailable, the system performs a quench to rapidly remove the magnetic field. This dynamic adaptation resolves the contradiction by selecting the appropriate method based on real-time system conditions.
Solution Approach 2:
An external dissipation device is introduced as an intermediary between the magnet and the quench process. This intermediary allows energy to be dissipated outside the magnet conductors, preventing the warming up that would otherwise occur during a quench. The dissipation device acts as a mediator that enables rapid field removal without the harmful thermal effects on the magnet itself.
2Reliability
If the emergency button is configured to always initiate a quench, then the magnetic field is rapidly removed in any emergency, but unnecessary quenching causes costly and time-consuming cooling periods
Solution Approach 1:
The system incorporates feedback from the state of the external dissipation device to determine the appropriate emergency response. The control system continuously monitors whether the dissipation device is available and operational, and uses this information to select between quenching and controlled ramp-down. This feedback mechanism ensures that quenching is performed only when necessary, eliminating unnecessary cooling periods while maintaining reliable emergency field removal.
Solution Approach 2:
The system changes the operational parameters of the magnet based on the available emergency response options. When an external dissipation device is available, the system uses controlled ramp-down with external energy dissipation. When no dissipation device is available, the system switches to quenching mode. This parameter change approach allows the system to adapt its emergency response to available resources, avoiding unnecessary quenching while ensuring reliable field removal.
3Loss of time
If the emergency button is configured to always initiate a controlled ramp down, then cooling time is minimized, but the magnetic field removal may be too slow for severe emergencies
Solution Approach 1:
The system dynamically selects between controlled ramp-down and quenching based on the severity of the emergency and the availability of external dissipation devices. For less severe emergencies or when dissipation devices are available, controlled ramp-down is used to minimize cooling time. For severe emergencies or when dissipation devices are unavailable, quenching is initiated to ensure rapid field removal. This dynamic selection resolves the contradiction by matching the response speed to the emergency severity.
Solution Approach 2:
The system uses feedback from emergency detection sensors and dissipation device status to determine the appropriate response speed. When sensors detect a severe emergency condition or when the dissipation device is unavailable, the system triggers a quench for rapid field removal. When conditions are less severe or dissipation is available, the system uses controlled ramp-down. This feedback-driven approach ensures the fastest appropriate response while minimizing unnecessary cooling time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for rapid and controlled management of MRI magnet states, minimizing damage and cooling times, enabling immediate system recovery post-emergency by differentiating between immediate quenching and controlled ramp-down operations.
Implementation Method 1
a superconductive magnet with windings for generating a magnetic field, the magnet being operable in a superconducting state and in a normal conductivity state
Implementation Method 2
A superconducting magnet is an electromagnet made from coils/windings of superconducting wire
Implementation Method 3
ramping down the magnetic field while dissipating energy stored in the windings of the magnet to an external dissipation device
Implementation Method 4
parts of the normally superconducting windings of the magnet are intentionally heated up resulting in conversion of the superconductor to normal conductivity state. This state spreads rapidly throughout the magnet and the energy stored in the magnet is dissipated as heat in the magnet conductors and internal structure
Implementation Method 5
conversion of the superconductor to normal conductivity state
Implementation Method 6
the magnet coil must be cooled below its critical temperature, i.e. the temperature at which the winding material changes from the normal resistive state and becomes a superconductor
Implementation Method 7
When liquid cooling is applied, typically liquid helium is used as a cryogen
Implementation Method 8
The helium gas formed by the boiling of liquid helium in the superconducting magnet helium pressure vessel is flowed through passageways in a recondenser cooled by a cryocooler to recondense the helium gas back to liquid helium
Data Source
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AI summary
The invention relates to a magnetic resonance imaging (MRI) system with emergency quench. According to the invention, a magnetic resonance imaging system (1) comprising a superconductive magnet (2) with windings (3) for generating a magnetic field, an emergency button (4) and a ciruitry logic (5) for controlling the magnet (2) coupled to the magnet (2) and to the emergency button (4), wherein the magnet (2) is operable in a superconducting state and in a normal conductivity state, respectively, and the emergency button (4) and the circuitry logic (5) are configured in such a way that, when the magnet (2) is operated in the superconducting state, actuating the emergency button (4) by a user in a predefined first way initiates ramping down the magnetic field while dissipating energy stored in the windings (3) of the magnet (2) to an external dissipation device (6), and actuating the emergency button (4) by a user in a predefined second way which is different from the first way initiates quenching the magnetic field by heating up at least part of the windings (3) of the magnet (2) leading to a dissipation of energy stored in the windings (3) of the magnet (2) as additional heat to the magnet (2). In this way, an easy and reliable way to control a superconductive magnet (2) of an MRI system (1) is provided in an event in which the magnetic field has to be removed.