Adjustable Current Bypasses for No-Insulation Magnet Field Correction
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Solution Overview
Problem
In tokamak fusion reactors with non-insulated toroidal field coils, variations in the number of ampere-turns across coils lead to magnetic field distortions due to localized current imbalances, which are difficult to correct without adding additional trim coils or current leads, potentially causing quench events and reducing magnetic field strength.
Innovation Solution
The implementation of programmable current bypass circuits across the terminals of individual field coils allows for controlled diversion of current, using controllable paths and sensors to adjust the magnetic field uniformly by diverting a portion of the current through a bypass circuit, thereby correcting ampere-turn imbalances and maintaining stable magnetic confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional trim coils are added to correct magnetic field distortions, then magnetic field uniformity is improved, but device complexity and risk of quench events increase
Solution Approach 1:
The patent extracts the field correction function from separate trim coils and relocates it to the existing TF coil circuitry by implementing programmable current bypasses. This removes the need for additional trim coils while maintaining field uniformity correction capability.
Solution Approach 2:
The existing TF coils are made multi-functional by enabling them to perform both their primary function of generating the main toroidal magnetic field and the secondary function of field trimming through programmable current bypasses. This eliminates the need for dedicated trim coils.
2Manufacturing precision
If additional trim coils are added to correct magnetic field distortions, then magnetic field uniformity is improved, but the risk of quench events increases
Solution Approach 1:
The patent removes the need for additional trim coils that would increase quench risk by implementing current bypasses within the existing TF coil circuitry. This reduces the number of independent current leads and potential quench sources.
Solution Approach 2:
The programmable current bypasses provide a pre-configured safety mechanism that can divert current away from coils experiencing localized current imbalances or heating, preventing quench events before they propagate through the entire magnet system.
3Manufacturing precision
If current is diverted through bypass circuits to correct ampere-turn imbalances, then magnetic field uniformity is improved, but current carrying capacity of the coil is reduced
Solution Approach 1:
The patent implements partial current diversion through programmable bypasses, where only the necessary fraction of current is diverted to correct field uniformity while the majority of current continues to flow through the coil to maintain required magnetic field strength and current carrying capacity.
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 precise adjustment of magnetic fields, reduces the risk of quench events, and maintains high plasma confinement without the need for additional trim coils, thereby enhancing the operational stability and efficiency of tokamak reactors.
Implementation Method 1
The coil has first and second terminals, a plurality of windings comprising a high temperature superconductor coupled between the first and second terminals... The bypass circuit is coupled to the first and second terminals of the coil in parallel with the plurality of windings, and has one or more controllable, current-carrying paths
Implementation Method 2
a plurality of windings comprising a high temperature superconductor coupled between the first and second terminals
Implementation Method 3
conductive material disposed between, and in electrical contact with, each of the plurality of windings
Data Source
AI summary
A magnet system and method of operating may be used in connection with operating a superconducting electromagnet, for example in a tokamak. The magnet system includes a coil having windings retained within a non-insulated structure, so that current can pass both along the windings to generate a magnetic field, and between the windings. The amount of current passing through the coil is trimmed using a bypass circuit, coupled in parallel to the coil terminals. The bypass circuit is controlled on the basis of measurements of the field components to divert current from passing through the field coil. In this way, the magnetic fields of each of multiple field coils can be brought into mutual uniformity.