Imaging motional Stark effect measurements at ASDEX Upgrade

Area of Science:

• Plasma physics
• Fusion energy research
• Diagnostic techniques

Background:

• The Imaging Motional Stark Effect (IMSE) is a crucial diagnostic for understanding plasma behavior in fusion devices.
• Its recent installation as a permanent diagnostic at ASDEX Upgrade marks a significant advancement.

Purpose of the Study:

• To present initial results from the IMSE diagnostic's first campaign at ASDEX Upgrade.
• To validate IMSE measurements against established methods and explore its capabilities for detailed plasma analysis.

Main Methods:

• Overview of the IMSE technique.
• Measurements of a standard H-mode discharge.
• Development of specialized discharges for pitch angle calibration.

Main Results:

• Good agreement between IMSE measurements and equilibrium reconstructions for standard discharges.
• Successful calibration of pitch angle using dedicated discharges.
• High-resolution observation of safety factor profile changes during sawteeth crashes, with accuracy to a few percent.

Conclusions:

• The IMSE diagnostic is a valuable and sensitive tool for ASDEX Upgrade.
• It provides accurate and high-resolution data for plasma physics research, particularly for studying dynamic events like sawteeth crashes.