Outer Vacuum Chamber Load Layout for MRI Magnet Ramp-Down Heat
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Solution Overview
Problem
Modern magnetic resonance systems with low helium content face challenges in dissipating energy from superconducting coils efficiently, leading to large and heavy aluminum storage facilities that occupy significant space, are difficult to transport, and cause altered dynamic vibration behavior due to asymmetric mass distribution.
Innovation Solution
Integrating a load facility, including diodes or resistors, within the outer vacuum chamber to convert electrical energy into thermal energy, and using a cold head for cooling, with optional external heat storage units, to manage energy dissipation and reduce system size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If aluminum storage facilities are used to dissipate energy from superconducting coils, then energy dissipation capacity is improved, but system weight and space requirements increase significantly
Solution Approach 1:
The patent changes the physical state of the heat storage material from solid aluminum to liquid nitrogen, utilizing its phase transition properties. Liquid nitrogen absorbs heat during evaporation, providing effective energy dissipation while dramatically reducing the mass required compared to solid aluminum storage facilities.
Solution Approach 2:
The invention employs the phase transition of liquid nitrogen from liquid to gas state to absorb and dissipate heat energy. This phase change process occurs at constant temperature (77K at atmospheric pressure), providing efficient heat absorption during the ramp-down of superconducting magnets without requiring large masses.
2Loss of energy
If large aluminum masses are used for energy storage, then energy dissipation is improved, but transportation and installation difficulty increase
Solution Approach 1:
The patent transforms the heat storage medium from solid aluminum requiring large volumes to liquid nitrogen which can be stored in compact pressurized containers. The liquid state and high density of nitrogen allow for much more compact storage and easier transportation compared to equivalent capacity aluminum facilities.
3Ease of operation
If asymmetric mass distribution is used for accessibility, then service accessibility is improved, but dynamic vibration behavior deteriorates
Solution Approach 1:
The invention replaces the large asymmetric aluminum mass with compact liquid nitrogen storage, which can be positioned more centrally or symmetrically in the magnet structure. The reduced mass and different distribution characteristics improve the dynamic vibration behavior while maintaining service accessibility through alternative access points.
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
The solution enables efficient energy dissipation and reduces the system's size and weight, allowing for quicker recovery from power failures and improved thermal insulation, thus enhancing operational reliability and accessibility.
Implementation Method 1
electrical current is introduced from the magnetic coil facility into the load facility
Implementation Method 2
the superconducting magnetic coils must be cooled for example to 4 K
Implementation Method 3
A vacuum is usually provided between the outer vacuum chamber and the cryoshield to largely prevent heat transfer from the outside to the inside
Data Source
AI summary
Techniques are provided for cooling a magnetic resonance system in a cost-effective and space-saving manner. For this purpose, a magnetic resonance system is proposed which has a superconducting magnetic coil facility, an outer vacuum chamber in which the superconducting magnetic coil facility is arranged, and a first load facility for ramping down the superconducting magnetic coil facility. An electric current is introduced from the magnetic coil facility into the load facility, and the first load facility is arranged within the outer vacuum chamber.