Magnet System Twin
A magnet twin tracks current, temperature margin, mechanical load, and quench risk in the superconducting coils that confine the plasma.
Watching the coils
The superconducting magnets are among the most highly stressed and least replaceable parts of a fusion machine. They carry enormous currents to produce strong fields, must stay below their critical temperature, and endure large mechanical forces. A magnet twin tracks their electrical, thermal, and mechanical state, forecasts remaining life, and watches for the conditions that could lead to a quench.
Temperature margin and quench
A superconductor carries current without resistance only below a critical surface set by temperature, field, and current density. The temperature margin is how much warming the coil can tolerate before it leaves the superconducting state. If a spot warms past the margin, resistance appears and heats further, a runaway called a quench that can damage the magnet. A twin estimates the margin continuously and flags erosion of it well before a quench.
What the twin tracks
- Coil currents and the resulting field, tied to the plasma configuration
- Temperature and coolant conditions, giving the temperature margin
- Mechanical stress from magnetic forces and thermal cycling
- Accumulated fatigue over the many cycles of operation
Why estimation is needed
The hottest spot and the highest stress point inside a coil are usually not where sensors sit. The twin reconstructs the internal thermal and mechanical fields from the sensors that do exist, through electromagnetic and structural models, so it can act on the true worst case rather than on what a gauge happens to read. This reconstruction is what turns scattered measurements into a quench-margin estimate.
In the Kronos machines
The Hyperion breeder operates at an on-axis field near 8 tesla with a peak of 16.84 tesla at the coils; the burner reaches 26.49 tesla in its tandem-mirror plug and 17 tesla at the throat, among the most demanding magnet requirements of any design. Their magnet twins track margin, stress, and fatigue against these design points. The methods are built on the design and materials models today, before hardware exists, and will be calibrated to each coil once the machines operate. See structural and fatigue twin and predictive maintenance.