Gaseous electron multiplier-based soft x-ray plasma diagnostics development: Preliminary tests at ASDEX Upgrade

Area of Science:

• Plasma physics
• Fusion energy research
• Detector technology

Background:

• Tokamak devices require advanced diagnostics for plasma control.
• Impurity transport studies are vital for future fusion reactors like ITER.
• Gaseous Electron Multiplier (GEM) detectors offer potential for X-ray detection.

Purpose of the Study:

• Develop a GEM-based detector for soft X-ray diagnostics on tokamaks.
• Facilitate tungsten impurity transport studies relevant to ITER.
• Evaluate detector performance in a harsh radiation environment.

Main Methods:

• Preliminary testing of a GEM detector at ASDEX Upgrade (AUG).
• Focus on operational aspects in a high-radiation environment.
• Data collection and comparison with existing AUG diagnostics.
• Simulations to understand contributions from high-energy photons.

Main Results:

• Spatially and spectrally resolved soft X-ray data were successfully collected.
• Data showed reasonable agreement with other AUG diagnostics.
• Contributions from hard X-rays, gammas, and neutrons to the GEM signal were identified.
• Simulations aided in understanding the impact of high-energy photons.

Conclusions:

• The GEM detector is suitable for soft X-ray diagnostics in tokamaks.
• The detector shows promise for impurity transport studies relevant to ITER.
• Understanding background radiation contributions is key for operational optimization.