Calorimetry probe for runaway electron heat load measurement at COMPASS

Area of Science:

• Fusion energy research
• Plasma physics
• Materials science

Background:

• Runaway electrons in tokamaks reach high energies, posing a significant risk to plasma-facing components.
• Effective mitigation strategies are crucial to prevent damage and ensure the operational integrity of fusion devices.

Purpose of the Study:

• To develop and validate a calorimetry probe for direct measurement of heat loads from runaway electrons.
• To assess the effectiveness of the probe in studying runaway electron mitigation strategies.

Main Methods:

• A calorimetry probe with embedded temperature sensors in a graphite body was designed and implemented.
• The probe was utilized in 250 tokamak discharges across four experimental campaigns (2019-2021).

Main Results:

• The calorimetry probe successfully measured direct heat loads deposited by runaway electrons.
• Measured deposited energy ranged from hundreds of joules to (15 ± 1) kJ, with a mean of (4.5 ± 1.1) kJ.

Conclusions:

• The developed calorimetry probe is a valuable diagnostic tool for studying runaway electron mitigation in tokamaks.
• Initial results provide crucial data for understanding and managing runaway electron impacts on fusion reactor components.