Passive SCR Coil Switching for Fusion Overcurrent Protection
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Solution Overview
Problem
Plasma disruption events in fusion devices can generate high-current beams, such as runaway electrons, causing severe damage to plasma-facing structures, which existing technologies struggle to mitigate effectively.
Innovation Solution
A passively activated switch system using silicon-controlled rectifiers (SCRs) and fast-acting mechanical switches, triggered by voltage increases during overcurrent events, to rapidly discharge current and prevent damage by creating electromagnetic forces that shunt current away from high-current coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If passive switching is used to protect against runaway electrons, then response time is improved, but device complexity increases due to multiple SCRs and fast-acting switches
Solution Approach 1:
The system divides the protection function into multiple parallel SCR circuits, each with its own fast-acting switch. This segmentation allows each component to operate independently and rapidly respond to overcurrent events, achieving fast protection while distributing the complexity across modular units rather than requiring a single complex switching mechanism
Solution Approach 2:
The patent introduces beam-bending conductors as intermediary elements that passively generate electromagnetic forces during plasma disruptions. These conductors automatically activate the fast-acting switches without requiring external control systems, thereby achieving rapid response time while minimizing the complexity of active control mechanisms
2Reliability
If fast-acting switches are used to shunt current, then protection effectiveness is improved, but loss of energy increases due to resistive heating
Solution Approach 1:
The system pre-configures dissipative resistors in parallel with each SCR circuit before disruption events occur. When overcurrent events happen, these pre-positioned resistors immediately begin dissipating energy through controlled resistive heating, protecting the plasma-facing components from damage while providing a predetermined energy dissipation path that limits uncontrolled energy loss
Solution Approach 2:
The patent employs current-sharing dissipative resistors whose resistance parameters are specifically designed to equalize current distribution across parallel SCR circuits. By optimizing the resistance values, the system ensures uniform current sharing that prevents any single resistor from bearing excessive power dissipation, thereby reducing total energy loss while maintaining effective protection
3Quantity of substance
If multiple SCRs are used in parallel, then current handling capacity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system uses current-sharing dissipative resistors with specifically designed resistance parameters to equalize current distribution across multiple parallel SCR circuits. By carefully selecting and matching resistance values, the patent compensates for variations in SCR characteristics, ensuring uniform current sharing that allows the system to handle high total current while reducing the precision requirements for individual component manufacturing
Solution Approach 2:
The patent employs identical, replicated SCR circuits connected in parallel, each with matching dissipative resistors and fast-acting switches. This copying approach allows for standardized manufacturing of modular units that can be assembled in parallel configurations, improving current handling capacity while maintaining consistent performance through replication rather than requiring high-precision custom manufacturing of each component
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 system efficiently prevents damage to high-current coils and associated systems by rapidly dissipating current, maintaining vacuum integrity, and protecting against relativistic electron beams without requiring external power.
Implementation Method 1
closes each of the plurality of SCRs to enable a loop current to create a large electromagnetic force. Each fast-acting switch is responsive to the large electromagnetic force
Implementation Method 2
Each fast-acting switch is responsive to the large electromagnetic force and configured to close to shunt current from each SCR
Data Source
AI summary
A passively activated switch system for a high-current coil including a plurality of silicon-controlled rectifiers (SCRs) each electrically coupled to a high-current coil, each SCR electrically coupled in parallel to a fast-acting mechanical switch. A passive voltage detector is responsive to an increase in voltage above a predetermined threshold value indicating a start of an over-current event which closes each of the plurality of SCRs to enable a loop current to create a large electromagnetic force. Each fast-acting switch is responsive to the large electromagnetic force and is configured to close to shunt current from each SCR to prevent damage of at least one of the high-current coils or a system that utilizes a high-current coil, or both.