Plasma Current 9.66 MA

The 9.66 MA plasma current confines the plasma and sets the safety factor; sustaining it without a large transformer drive is a core design problem.

What the current does

The 9.66 MA plasma current generates the poloidal magnetic field that, combined with the toroidal field, twists field lines into the nested surfaces that confine the plasma. Current sets the edge safety factor, strongly influences confinement, and defines how much plasma pressure the configuration can hold. It is not incidental — 9.66 MA is a defining parameter of the operating point.

A tokamak traditionally drives this current inductively, like the secondary of a transformer, but that is inherently pulsed. For steady foundry operation Hyperion leans on non-inductive sources — bootstrap current and external current drive — to sustain 9.66 MA without relying solely on a transformer that eventually runs out of flux.

Why sustaining it is hard

External current drive is power-hungry and counts against gain. The design therefore wants as much of the 9.66 MA as possible to come from the self-generated bootstrap current, minimizing the driven fraction. The exact split between bootstrap, driven, and ohmic current is a design-and-simulation result, and the achievable bootstrap fraction is a key sensitivity for the whole operating point.

• 9.66 MA sets poloidal field, safety factor, and pressure limit
• Steady operation needs non-inductive sustainment
• Higher bootstrap fraction lowers the gain penalty from current drive

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.