Mechanical Superconducting Switch With Infinite Off Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional superconducting switches for MRI magnets suffer from high heat dissipation and limited 'off' resistance, requiring ancillary coils and thermal heaters, which are unstable and inefficient, especially in cryogen-free designs where cooling power is limited.
Innovation Solution
A mechanically operated superconducting switch using the wire ends of the magnet coils themselves, with no separate ancillary coil, employing mechanical action and BiPb or similar superconducting material blocks for contact, providing practically infinite 'off' resistance and minimizing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional superconducting switches with ancillary coils and thermal heaters are used, then switching operation is achieved, but heat dissipation increases and stability decreases
Solution Approach 1:
The invention extracts and eliminates the ancillary superconducting coil from the switch structure, using only the magnet coil wires themselves. This removes the source of heat dissipation associated with ancillary coils while maintaining the switching function through direct mechanical contact of wire ends.
Solution Approach 2:
The invention replaces the thermal heater mechanism with a purely mechanical switching system. Wire ends are brought into direct mechanical contact to close the circuit and separated to open it, eliminating the need for thermal heating and associated heat dissipation while improving reliability.
2Reliability
If ancillary superconducting coils with CuNi matrix are used, then switching function is provided, but temperature and wire instabilities occur due to flux jumping
Solution Approach 1:
The invention uses homogeneous superconducting wire material (such as NbTi or Nb3Sn) throughout the switch structure, eliminating the heterogeneous CuNi matrix found in conventional ancillary coils. This homogeneity prevents flux jumping and associated thermal instabilities while maintaining superconducting properties.
3Productivity
If conventional switches with limited open-circuit resistance are used, then current switching is achieved, but ramp rate is limited and heat dissipation occurs during energisation
Solution Approach 1:
The invention extracts the limiting factor of conventional switches by eliminating the ancillary coil structure that imposed resistance limitations. The direct mechanical contact of superconducting wire ends provides effectively infinite open-circuit resistance when open, enabling much faster ramp rates and eliminating heat dissipation during energisation.
4Ease of operation
If thermal heaters are used to open and close the switch, then switching operation is achieved, but cooling power requirements exceed typical cryogenic refrigerator capacity
Solution Approach 1:
The invention replaces the thermal heater-based switching mechanism with a purely mechanical system. Wire ends are mechanically contacted to close the switch and separated to open it, eliminating the need for thermal heating and cooling. This reduces cooling power requirements to well within the capacity of typical 4.2K cryogenic refrigerators.
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 achieves persistent current switching with minimal heat dissipation, increased ramp rates, and improved stability, utilizing the magnet's own wire ends and copper matrix for enhanced performance, suitable for cryogen-free MRI magnets.
Implementation Method 1
A mechanically operated superconducting switch using the wire ends of the magnet coils themselves, with no separate ancillary coil, employing mechanical action and BiPb or similar superconducting material blocks for contact
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
A mechanically operating superconducting switch comprising two superconducting wires (10, 12), a respective end of each superconducting wire being embedded in a respective block (13, 14; 42, 52) of superconducting material. A mechanical arrangement (24, 16, 18, 20; 60) is provided for driving respective contact surfaces (15) of the two blocks into physical contact with one another, and for separating them.