Hyperion Current Drive
Non-inductive current drive sustains the 9.86 MA plasma current after the central solenoid's inductive flux runs out.
Keeping the current flowing
The central solenoid can only drive plasma current while its own current is ramping, so its inductive drive is finite. To run beyond that, Hyperion must sustain its 9.86 MA plasma current non-inductively, using external systems that push current without relying on a changing solenoid flux.
How current is driven without induction
- Neutral-beam injection carries momentum into the plasma in a preferred toroidal direction, dragging current with it.
- Radio-frequency waves can be launched to push electrons preferentially one way around the torus.
- The plasma also self-generates a bootstrap current from its own pressure gradient, which reduces how much external drive is needed.
The bootstrap contribution
A well-shaped, high-pressure plasma spontaneously drives a fraction of its own current, the bootstrap current, arising from the pressure gradient across the confining field. Maximizing this fraction is a design goal because current that the plasma provides for free is current the external systems do not have to supply, which improves the overall gain picture.
In the model
Current drive is not a single visible box but a function shared with the heating systems and the plasma itself. The model attributes it to the beam lines and RF launchers at their ports and notes the bootstrap fraction as a plasma property rather than a hardware component.
Why it matters for pulse length
Effective non-inductive drive is what separates a short inductive pulse from a long, steady operation. See the central solenoid whose flux it replaces and the heating systems it shares hardware with.