MRI Superconducting Magnet Energization via Gradient Amplifier
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Solution Overview
Problem
Energizing and discharging superconducting magnets in MRI systems is inefficient and costly due to the need for specialized power supplies and diodes, which increases operational effort and expenses.
Innovation Solution
A MRI system design that includes a switch assembly for galvanically coupling the superconducting field coil to the gradient amplifier and coil, allowing for energization and discharge through the gradient system, with a quench assembly to manage current reduction and helium evaporation, enabling efficient energy transfer and reduced cooling needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized power supplies and diodes are used for energizing and discharging superconducting magnets, then reliable energization and discharge can be achieved, but operational effort and expenses increase
Solution Approach 1:
The gradient amplifier, originally designed solely for driving gradient coils, is adapted to perform the additional function of energizing the superconducting magnet. The same amplifier now serves dual purposes: driving gradient coils during MRI operation and delivering controlled current ramps for magnet energization, eliminating the need for separate dedicated power supplies
Solution Approach 2:
The gradient amplifier utilizes its own internal power supply and control circuitry to perform magnet energization without requiring external specialized equipment. The system serves itself by leveraging existing components (amplifier, gradient coil, switch assembly) to accomplish the energization task that would traditionally require separate dedicated equipment
2Reliability
If dedicated magnet power supplies and discharge diodes are provided, then proper energization and discharge control is achieved, but device complexity and costs increase
Solution Approach 1:
The patent combines multiple previously separate systems into a unified configuration. The gradient amplifier, gradient coil, and switch assembly work together as an integrated system for magnet energization, merging the functions of power supply, current control, and magnetic field generation into a coordinated sequence using existing components
Solution Approach 2:
The gradient amplifier is designed to perform multiple functions: driving gradient coils during normal operation and energizing the superconducting magnet during startup. This multi-functionality eliminates the need for dedicated magnet power supplies and reduces overall system complexity
3Power
If high currents of 480 A and ramp voltage of 5 V are used for energizing, then sufficient power delivery is achieved, but energy dissipation in the magnet increases
Solution Approach 1:
The gradient coil is pre-cooled to cryogenic temperatures before energization begins, establishing a low-temperature thermal environment in advance. This preliminary cooling action reduces the thermal mass and heat capacity of the gradient coil, minimizing energy dissipation during the subsequent high-current energization process
Solution Approach 2:
The energization process maintains continuous current ramping through the gradient coil without interruption, ensuring that the magnetic field builds up smoothly and continuously. This continuous action prevents energy losses associated with intermittent operation and maintains optimal efficiency throughout the energization sequence
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 approach simplifies and cost-reduces the energizing and discharging processes by leveraging the gradient system for power delivery and cooling, reducing the magnetic energy stored in the superconducting field coil to 4% of its nominal value without additional cooling, and allowing operation in persistent mode.
Implementation Method 1
a superconducting magnet assembly with a superconducting field coil for generating a stationary uniform main magnetic field
Implementation Method 2
a gradient system including a gradient coil for generating gradient magnetic fields
Implementation Method 3
activate the quench assembly when the electrical DC current strength falls below the threshold value. This aspect of the invention enables the discharge the superconducting field coil resistively through the gradient coil(s) until the electrical current strength in the superconducting field coil is reduced to the pre-determined threshold value and then the superconductive field coil is further down-ramped via the quench assembly where the remaining liquid Helium is quickly evaporated
Data Source
AI summary
A magnetic resonance imaging (MRI) system includes a superconducting magnet assembly with a superconducting field coil for generating a stationary uniform main magnetic field. A gradient system includes a gradient coil for generating gradient magnetic fields and a gradient amplifier which is connectable to the gradient coil for driving the gradient coil. A switch assembly is adapted for galvanically coupling the superconducting field coil to the gradient amplifier. In this way, it is possible for energizing and discharging a superconducting magnet of an MRI system in an easy and cost-efficient way.