Superconducting MRI Magnet Rapid Field Ramping Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MRI systems with superconducting magnets face challenges in rapidly ramping up and down magnetic fields due to the need for expensive liquid cryogens and the time-consuming process of cooling and heating, which is not feasible for interventional and mobile imaging applications.
Innovation Solution
A control system using a superconducting switch and mechanical cryocooler to rapidly adjust the magnetic field by connecting and disconnecting the superconducting magnet from a power supply, allowing for rapid changes in current density while maintaining the magnet coils below the superconducting transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If liquid helium is used to cool superconducting magnet coils to achieve high magnetic field strengths, then the magnetic field strength is improved, but the system becomes expensive and unable to rapidly turn on or off the magnetic field
Solution Approach 1:
The patent extracts the magnet coils from the liquid cryogen environment and places them in a dry, cryogen-free environment. The magnet coils are cooled to cryogenic temperatures using a cryocooler but operate without immersion in liquid helium, allowing rapid field changes without the constraints of cryogen management.
Solution Approach 2:
The patent introduces a cryocooler as an intermediary device to cool the magnet coils to cryogenic temperatures without requiring liquid cryogens. This mediator enables the coils to achieve superconducting states while eliminating the need for liquid helium, thus allowing rapid field ramping.
2Speed
If current is rapidly changed in superconducting magnet systems to turn the magnetic field on or off quickly, then the speed of field ramping is improved, but heating occurs that boils off liquid cryogens
Solution Approach 1:
The patent removes the liquid cryogen from the system entirely, replacing it with a cryocooler-based cooling mechanism. This extraction eliminates the substance loss problem while enabling rapid current changes and field ramping without the risk of boiling off cryogens.
Solution Approach 2:
The patent replaces the thermal-mechanical system of liquid cryogen cooling with an electrical-controlled cryocooler system. This substitution allows precise control of cooling while eliminating the phase change issues that occur with liquid cryogens during rapid field changes.
3Loss of substance
If current is changed slowly in superconducting magnet systems to avoid heating, then liquid cryogen loss is reduced, but the time required to ramp the magnetic field increases to many hours
Solution Approach 1:
The patent replaces the passive liquid cryogen cooling system with an active cryocooler system that can rapidly respond to thermal loads. This substitution enables fast field ramping by providing controlled cooling capacity that matches the thermal demands of rapid current changes.
Solution Approach 2:
The patent implements a dynamic cooling system using a cryocooler that can adjust its cooling capacity in real-time to match the thermal demands of rapid field changes. This dynamic response allows fast ramping without the thermal management constraints of static liquid cryogen systems.
4Speed
If a quench mechanism is used to rapidly turn off the magnetic field in emergency situations, then the speed of field shutdown is improved, but the system requires time-consuming and expensive replacement of liquid cryogens
Solution Approach 1:
The patent extracts the liquid cryogen from the system and replaces it with a cryocooler-based cooling mechanism. This elimination of liquid cryogens means that emergency shutdowns via quenching do not result in substance loss or require time-consuming replacement operations.
Solution Approach 2:
The patent converts the potential harm of quenching (rapid uncontrolled heating and cryogen loss) into a beneficial outcome by operating in a cryogen-free environment. The same quench mechanism that would normally cause cryogen loss now simply dissipates energy without material loss, enabling rapid shutdowns without operational disruption.
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
Enables rapid ramping of the magnetic field up and down in minutes, reducing the need for expensive cryogens and allowing for safe storage and transportation of MRI systems, while maintaining superconducting properties.
Implementation Method 1
A control system using a superconducting switch and mechanical cryocooler to rapidly adjust the magnetic field by connecting and disconnecting the superconducting magnet from a power supply
Implementation Method 2
maintaining the magnet coils below the superconducting transition temperature
Implementation Method 3
A control system using a superconducting switch and mechanical cryocooler to rapidly adjust the magnetic field by connecting and disconnecting the superconducting magnet from a power supply
Data Source
AI summary
Systems and methods for rapidly ramping the magnetic field of a superconducting magnet, such as a superconducting magnet adapted for use in a magnetic resonance imaging system, are provided. The magnetic field can be rapidly ramped up or down by changing the current density in the superconducting magnet while monitoring and controlling the superconducting magnet's temperature to remain below a transition temperature. A superconducting switch is used to connect the superconducting magnet and a power supply in a connected circuit. The current generated by the power supply is then adjusted to increase or decrease the current density in the superconducting magnet to respectively ramp up or ramp down the magnetic field strength in a controlled manner. The ramp rate at which the magnetic field strength is changed is determined and optimized based on the operating parameters of the superconducting magnet and the current being generated by the power supply.