Deep Dive: Heating & Current-Drive Systems

Reaching 65–70 keV and sustaining current takes neutral beams and RF waves. In Kronos they do double duty — heating the plasma and driving non-inductive current.

Goal

Reach 65–70 keV; sustain current

Methods

Neutral beams + RF (EBW, HHFW)

Current drive power

62 MW (f_NI = 0.61–0.81)

Special role

HHFW launcher for channeling (P6)

Getting a plasma to fusion temperature and keeping its current flowing takes dedicated heating and current-drive systems — and in a well-designed machine, the same hardware does both.

Kronos MetroVolt uses neutral beam injection (fast neutral atoms that ionize and deposit energy in the core) together with radio-frequency waves — electron Bernstein waves (EBW) and high-harmonic fast waves (HHFW), both well matched to the low-field, high-density spherical-tokamak regime. Together they heat the plasma to 65–70 keV and drive non-inductive current (62 MW, for a total non-inductive fraction of 0.61–0.81).

Beyond heating, these systems set rotation (via beam torque) and — in the case of the HHFW launcher — provide the tool for the fast-ion channeling demonstration (P6). The current-drive frontier is priced explicitly rather than assumed. See current drive & bootstrap.