Rotating Superconducting Coil Cryogenic Cooling
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Solution Overview
Problem
Conventional cooling systems for superconducting coils in rotatable particle accelerators face challenges such as bulkiness, high cryogen consumption, and interference issues due to the need for large cryogen baths and thermal conductors, which hinder efficient cooling and stability of the magnetic field.
Innovation Solution
A cooling system comprising a local cryogen chamber with highly thermally conductive means for heat transfer to vaporize cryogen and a recondensing unit for vaporized cryogen to be recondensed and reused, allowing for efficient cooling of superconducting coils during rotation without the need for large cryogen baths or direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large cryogen bath is used to cool the superconducting coil, then the cooling effectiveness is improved, but the system becomes bulky and unsuitable for rotation
Solution Approach 1:
The system divides the cooling function into two separate components: a compact cryogen chamber that rotates with the particle accelerator and a stationary recondensing unit. This segmentation allows the rotating part to be small and lightweight while maintaining effective cooling through the thermally conductive link.
Solution Approach 2:
A thermally conductive link acts as an intermediary between the rotating cryogen chamber and the stationary recondensing unit. This intermediary transfers heat efficiently while allowing mechanical separation, enabling the rotating component to be compact without compromising cooling performance.
2Reliability
If a pressure vessel is used to contain the cryogen, then the system can withstand high pressures from vaporisation, but the system becomes more complex and bulky
Solution Approach 1:
The pressure containment function is separated from the rotating cooling system. The cryogen chamber is small and doesn't require heavy pressure vessel construction because the recondensing unit, which handles vaporization pressures, is stationary and can be properly engineered for pressure containment.
Solution Approach 2:
The pressure vessel requirements are extracted from the rotating component and placed in the stationary recondensing unit. This allows the rotating particle accelerator to be lightweight and compact while the stationary unit handles the bulky pressure containment functions.
3Temperature
If thermal conductors are used to transfer heat from the coil, then cooling is achieved, but the temperature gradients degrade performance
Solution Approach 1:
The thermally conductive link serves as an optimized intermediary that minimizes temperature gradients. By designing this link with high thermal conductivity and appropriate geometry, the system achieves efficient heat transfer from the coil to the cryogen chamber while maintaining stable temperatures and minimizing performance-degrading gradients.
4Volume of moving object
If the particle accelerator is made compact for rotation, then the system size is reduced, but the magnetic field intensity decreases
Solution Approach 1:
The system uses superconducting coils which operate at cryogenic temperatures to achieve much higher current densities than conventional resistive coils. This parameter change (operating temperature) enables compact dimensions while maintaining or enhancing magnetic field intensity, as superconducting wires can carry hundreds or thousands of amperes without dissipation.
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 enables a compact, lightweight, and efficient cooling system that maintains stable temperatures for superconducting coils, reducing interference and allowing for stronger magnetic fields, thus enabling a more compact and cost-effective particle accelerator design suitable for various applications.
Implementation Method 1
thermally conductive means arranged to facilitate heat transfer from the at least one superconducting coil to the cryogen chamber to vaporize cryogen contained therein
Implementation Method 2
highly thermally conductive means for heat transfer
Implementation Method 3
the cryogen absorbs heat from the superconductor
Implementation Method 4
a cryogen recondensing unit in fluid communication with the cryogen chamber, whereby vaporized cryogen may flow from the cryogen chamber to the cryogen recondensing unit to be recondensed
Data Source
AI summary
An ion therapy system comprises a particle accelerator (1) mounted on a rotatable gantry (2). The particle accelerator includes a superconducting coil (17) which rotates about its axis as the particle accelerator rotates about the gantry axis in use to direct an output beam towards a target from different directions. The particle accelerator is rotatable through (180) degrees to move the beam through a corresponding arc. The particle accelerator includes cooling system arranged to cool the coil as the coil rotates. The superconducting coil (17) is mounted in a coil support (25). The coil is surrounded by a cryogen chamber (32) which is located radially outwardly from the coil (17) on the other side of the support (25). The cryogen chamber is in fluid communication with a cryogen recondensing unit (29) whereby vaporized cryogen may flow from the cryogen chamber (32) to the cryogen recondensing unit (29) to be recondensed in use before returning to the cryogen chamber. Thermally conductive means (40) is arranged to facilitate heat transfer from the superconducting coil (17) to the cryogen chamber (32) to vaporize cryogen contained therein in use and thereby remove heat from the coil.