Electron Cyclotron Emission
ECE radiometry measures the electron temperature profile and its fluctuations from the plasma's own cyclotron emission, fast and spatially resolved.
Temperature from emission
Electrons gyrating in the magnetic field emit at the cyclotron frequency and its harmonics. Because that frequency depends on the local field strength, a radiometer tuned across frequencies maps emission to position, and the emission intensity gives the local electron temperature. ECE thus delivers a fast, spatially resolved temperature profile continuously between pulsed Thomson measurements.
Field-to-position mapping
The frequency-to-position mapping depends directly on the field profile, which in the breeder runs to 16.84 T peak (8 T on-axis). The fabric applies the reconstructed field to place each ECE channel, then normalizes into flux coordinates. This coupling means an ECE channel's localization is only as good as the equilibrium it rests on, tracked in lineage.
Into features
- ECE temperature complements Thomson in the core pressure map, adding time resolution.
- ECE fluctuations reveal MHD and transport structure, feeding precursor features.
- Cross-checking ECE against Thomson temperature is a standing validation test.
- A channel whose emission goes optically thin is flagged rather than trusted blindly.
Both machines
On the breeder, ECE gives the fast temperature profile the pressure map and stability analysis need. On the burner, cyclotron-based temperature measurements characterize the central-cell electrons whose confinement the ambipolar potential governs. Channel-to-frequency calibration is versioned per machine.