The project at a glance
The project turns years of laboratory research and development into a working plasma diagnostic. The forward-looking goal is a compact, innovative diagnostic able to operate in an intense neutron/gamma environment and to combine reflectometry, interferometry and polarimetry (and ECE in perspective) in a single instrument. The test on WEST provides the elements needed to build the dedicated diagnostic for the DTT (Divertor Tokamak Test, ENEA Frascati) experiment.
The THz-TDS technique
Sub-picosecond electromagnetic pulses let us measure the amplitude and phase of the transmitted or reflected field, from which the optical properties (refractive index, absorption) of the medium are obtained over a broad band. The same physics, applied to a magnetically confined plasma, underpins several diagnostic channels at once.
Scientific objectives
- Consolidate the THz-TDS instrument — already built and proven in the laboratory, where it has been used to characterise fusion-relevant materials and windows in the terahertz band — into a multifunctional plasma diagnostic (reflectometry, interferometry, polarimetry; ECE in perspective).
- Adapt the bench to tokamak operating conditions (optical access, vibrations, magnetic fields, neutron/gamma environment).
- Optimise the technique's performance (bandwidth, signal-to-noise, time resolution) against the diagnostic requirements.
- Install and test the diagnostic on WEST (CEA Cadarache), obtaining representative plasma measurements and validating them against the established diagnostics, exploiting WEST's long pulses.
- Acquire the elements needed to build the dedicated diagnostic for the DTT experiment (ENEA Frascati).
Why it matters
The Enabling Research scheme funds basic and frontier research that can enable solutions for future fusion devices. Beyond DTT, the competences developed on terahertz / millimetre-wave diagnostics feed the laboratory's work lines towards ITER and the demonstration reactor DEMO. A closely related activity is the development of the ECE diagnostic for DEMO; the exploratory THz-TDS line and the ECE line share the same competences (see also the THz and Reflectometry pages).
Key publications
- M. Zerbini, “Plasma diagnostic techniques based on terahertz radiation”, Applied Physics Reviews 12 (2025).
- G. Galatola Teka et al., “A thorough experimental assessment of THz-TDS plasma diagnostic techniques for nuclear fusion applications”, Review of Scientific Instruments.
- M. Zerbini, “Sailing on Far-Infrared and Submillimeter-Wave Plasma Diagnostics, towards THz-TDS and beyond” (invited), IRMMW-THz, Delft (2022).