Electron-Cyclotron Heating and Current Drive
ECRH modeling combines ray-tracing and Fokker-Planck physics to predict the highly localized heating and current drive from electron-cyclotron waves.
Resonant electron heating
Electron-cyclotron waves are launched at the frequency where electrons gyrate, or a harmonic of it. Where that resonance occurs in the plasma, the wave transfers energy directly to electrons. Because the resonance is a narrow layer set by the magnetic field, deposition is exceptionally localized and steerable.
The modeling chain
A ray-tracing code follows the launched beam to the resonance layer and computes absorption; a Fokker-Planck solver then determines how the absorbed power reshapes the electron distribution and how much current results. The combination predicts both the heating profile and the current-drive efficiency as functions of launch angle.
Why localization matters
- Central deposition heats the core to raise fusion reactivity
- Off-axis deposition shapes the current profile for stability
- Precisely aimed deposition drives current inside a magnetic island to suppress tearing modes
Steering and control
Because the deposition location depends on the launch geometry and the local field, movable mirrors can steer the beam in real time. Modeling predicts the accessible deposition range and the aiming accuracy required, informing both antenna design and the control algorithms that use ECRH for stabilization.
Design integration
ECRH is valued for its flexibility: the same system can heat, drive current, and stabilize instabilities depending on where it is aimed. Modeling quantifies these trade-offs so a design carries enough power and steering to meet its stability and scenario needs.
For the Hyperion breeder, localized electron-cyclotron current drive is a candidate tool for neoclassical-tearing-mode suppression, and its modeling ties directly to the island-stabilization analysis.