Vertical electron cyclotron emission diagnostic on the tokamak à configuration variable

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Diagnostic Techniques

Background:

• Electron Cyclotron Emission (ECE) is crucial for understanding fusion plasmas.
• Previous ECE diagnostics faced limitations due to signal pollution from refraction.
• Non-thermal electrons significantly impact plasma behavior and energy confinement.

Purpose of the Study:

• To present a novel Vertical ECE (V-ECE) diagnostic for measuring non-thermal electrons.
• To overcome signal interference caused by refraction in magnetically confined plasmas.
• To enable direct inference of emitting electron energies.

Main Methods:

• Utilizing a vertical viewing line of sight for direct electron energy measurement.
• Mitigating refraction by tuning the toroidal magnetic field on the Tokamak à Configuration Variable (TCV).
• Carefully selecting ECE spectrum frequencies to reduce background radiation.
• Developing a novel calibration technique based on plasma measurements and modeling.

Main Results:

• Successfully reduced background radiation power below instrumentation noise levels.
• Demonstrated the mitigation of refraction effects on the ECE signal.
• Achieved direct inference of electron energies from the V-ECE measurements.
• Presented the first results from the V-ECE diagnostic on TCV.

Conclusions:

• The V-ECE diagnostic offers a significant advancement for studying non-thermal electrons in fusion plasmas.
• The developed methods effectively address and overcome previous limitations of ECE diagnostics.
• This diagnostic provides a reliable tool for inferring electron energy distributions, crucial for fusion energy development.