Vertical Stability and Control

The elongated plasma is vertically unstable and drifts into the wall without fast feedback; active control holds it in place.

A plasma that wants to move

Elongating the plasma to raise current and pressure capacity has a price: a tall plasma is vertically unstable. Perturbed upward or downward, it tends to keep moving in that direction — a vertical displacement event — until it reaches the wall, unless something pushes it back. The stronger the elongation, the faster the instability grows.

Hyperion's shaping makes vertical stability an active-control requirement. A set of coils, driven by fast feedback that senses the plasma position, continuously pushes the plasma back toward center on a timescale faster than the instability grows. Lose that feedback and the plasma moves off-axis, which can trigger a disruption.

Why it is a physics gate, not just engineering

The growth rate of the vertical instability, and therefore how fast the control must react, follows from the plasma shape, the surrounding conducting structures, and the coil configuration. Demonstrating that the feedback system can stabilize the design plasma with adequate margin is a coupled physics-and-control problem. It is one of the reasons Hyperion is developed alongside a real-time plasma-control capability, and its adequacy is a design-and-simulation result.

• Elongation buys performance but causes vertical instability
• Fast feedback coils hold the plasma on-axis
• Loss of control can lead to a disruption

This page describes a design-and-simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. No hardware net-gain is claimed before FOAK.