Superconducting Magnet Quench Dissipation Outside the Cryostat
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Solution Overview
Problem
Conventional cryogenically cooled superconducting magnets face challenges in efficiently dissipating energy during a quench, leading to excessive heat within the cryostat, which results in high cryogen consumption and potential coil damage.
Innovation Solution
The introduction of a second superconducting switch with a resistive heating element and a high power resistor, allowing a significant fraction of the magnet's energy to be dissipated externally, reducing heat within the cryostat and cryogen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quench energy is dissipated within the cryostat using conventional methods, then the magnet coil is protected from localized overheating, but excessive heat remains inside the cryostat causing rapid cryogen boil-off and increased cooling time
Solution Approach 1:
The patent extracts the energy dissipation function from the cryostat interior to the exterior environment. By connecting a quench resistor outside the cryostat through a current lead, the majority of quench energy is dissipated externally, removing the harmful thermal load from the cryogen-containing environment while still protecting the coil through controlled current decay.
Solution Approach 2:
The patent introduces a current lead as an intermediary element that bridges the interior and exterior of the cryostat. This intermediary allows controlled transfer of quench current from the protected coil environment to the external resistor, enabling energy dissipation outside while maintaining coil protection through the controlled decay path.
2Use of energy by stationary object
If quench energy is dissipated within the cryostat, then the magnetic field energy is converted to heat, but this heat rapidly boils the liquid cryogen and expels it from the cryostat
Solution Approach 1:
The patent extracts the energy conversion location from inside the cryostat to outside. The quench resistor is positioned externally, so when quench occurs, the magnetic field energy is converted to heat in the external resistor rather than inside the cryostat, preventing cryogen boil-off while still achieving the necessary energy dissipation.
Solution Approach 2:
The patent converts the harmful effect of quench energy (which would boil cryogen if dissipated internally) into a beneficial external heat dissipation process. The same energy conversion mechanism is used, but relocated to where the heat has no harmful effect on the cryogen system, turning a potential damage mechanism into a protective feature.
3Loss of substance
If a second superconducting switch with resistive heating element is introduced, then energy dissipation occurs outside the cryostat, but the device complexity increases
Solution Approach 1:
The patent makes the current lead serve multiple functions: it provides electrical connection for normal operation and simultaneously serves as a quench protection path during quench events. This multi-functionality reduces the need for separate dedicated quench protection components, minimizing added complexity while achieving external energy dissipation.
Solution Approach 2:
The patent enables the quench protection system to activate automatically through the inherent voltage generated during quench. The resistive heating element and external resistor configuration allows the system to self-activate without external control signals, using the quench-induced voltage to drive current through the external dissipation path, thereby reducing control system complexity.
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 effectively reduces cryogen consumption and subsequent cooling time by dissipating most of the magnet's energy outside the cryostat, minimizing the risk of coil damage and optimizing the magnet's operational availability.
Implementation Method 1
a second superconducting switch with a resistive heating element and a high power resistor allows for the dissipation of a significant fraction of the magnetic field energy outside the cryostat
Implementation Method 2
a superconducting magnet is typically made up of a number of coils of superconducting wire, cooled to a cryogenic temperature, typically about 4K, at which superconductivity is possible
Implementation Method 3
The copper provides mechanical protection, and a parallel current path which carries current when the superconducting wire filaments are in their 'normal', resistive, mode
Data Source
AI summary
An energy dissipation arrangement for a cryogenically cooled superconductive magnet comprising a plurality of superconductive coils (10) connected in series and housed within a cryostat (24), comprising a superconducting switch (25) having a superconductive current path (28) in series with the superconductive coils (10); and a resistor (38), external to the cryostat, electrically connected in parallel with the superconductive current path (28) of the superconducting switch (25). The superconductive switch is arranged (26, 32, 30) to open in response to an electric current applied to an associated heater (26; 40)