Inductive Energizing of Superconducting MRI Magnets
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Solution Overview
Problem
Conventional methods for energizing superconducting magnets in MRI systems are costly and result in liquid helium loss due to heavy, expensive power supplies and high current leads, which can lead to magnetic field drift and affect MRI performance.
Innovation Solution
A system that includes a cryostat with a first coil inside and a second coil outside, configured for inductive coupling to the main coil, with a controller to control both coils and induce current in the main coil, reducing helium loss and costs by using a low current AC power supply and minimizing physical connections between cryogenic and room temperature environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large power supply with high rated current leads is used to energize the superconducting magnet, then the magnet can be energized effectively, but liquid helium is lost and costs increase
Solution Approach 1:
The patent replaces the conventional direct electrical connection system (current leads) with an inductive coupling system using magnetic fields. The external coil generates a time-varying magnetic field that induces current in the superconducting main coil, eliminating the need for physical current leads that penetrate the cryogenic boundary and cause helium leakage.
Solution Approach 2:
The patent introduces an external coil as an intermediary device that transfers energy to the superconducting magnet through magnetic induction rather than direct electrical contact. This intermediary approach allows energy transfer across the cryogenic boundary without requiring physical penetration, thus preventing helium loss.
2Power
If a large power supply is used to provide current to the superconducting magnet coils, then the magnet can be energized, but the power supply becomes heavy and expensive
Solution Approach 1:
The patent replaces the heavy conventional power supply system with an external coil that uses magnetic induction to transfer energy. The external coil can be designed with lighter materials and structures since it does not need to handle high currents directly through physical connections, significantly reducing the overall system weight.
3Power
If high rated current leads are used to handle high electrical current, then the magnet can be energized, but the connections lead to loss of liquid helium
Solution Approach 1:
The patent extracts and removes the current leads entirely from the system by using inductive coupling. The external coil provides the necessary magnetic field to induce current in the main coil without requiring any physical connection or lead that would penetrate the cryogenic boundary and cause helium leakage.
Solution Approach 2:
The patent substitutes the mechanical/electrical connection system (current leads) with a magnetic field-based inductive coupling system. This eliminates the need for physical penetrations through the cryostat wall, preventing the pathway for liquid helium to escape.
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 effectively energizes the superconducting magnet with reduced helium loss and lower operational costs, maintaining a stable magnetic field and improving MRI system performance.
Implementation Method 1
a second coil coupled to the first coil and positioned external to the housing of the cryostat, the second coil configured to inductively couple to the main coil
Data Source
AI summary
A system for energizing a main coil of superconducting magnet in a magnetic resonance imaging (MRI) system includes a cryostat comprising a housing. A first coil is positioned within the housing of the cryostat. Alternatively, the first coil may be positioned external to the housing of the cryostat. A second coil is coupled to the first coil and positioned external to the housing of the cryostat. The second coil is configured to inductively couple to the main coil. A controller is coupled to the first coil and the second coil and is configured to control the first coil and the second coil to induce current in the main coil.