Microwave imaging reflectometry studies for turbulence diagnostics on KSTAR

Area of Science:

• Plasma physics
• Microwave diagnostics
• Fusion energy research

Background:

• Conventional reflectometry faces challenges with large amplitude and high wavenumber fluctuations at the reflection layer.
• The first prototype microwave imaging reflectometry (MIR) system demonstrated laboratory advantages not fully realized in plasma operations.
• Discrepancies in MIR system performance necessitate further investigation.

Purpose of the Study:

• To understand the causes of MIR system performance degradation in plasma environments.
• To present findings on MIR performance issues observed on the TEXTOR tokamak.
• To introduce a concept for a multifrequency MIR system design for the KSTAR tokamak.

Main Methods:

• Thorough investigation of MIR system performance at POSTECH.
• Analysis of discrepancies between laboratory tests and plasma operations.
• Conceptual design of a multifrequency MIR system.

Main Results:

• Identified a possible cause for MIR performance degradation on TEXTOR.
• Highlighted the gap between laboratory demonstrations and real-world plasma applications.
• Proposed a new multifrequency MIR system concept.

Conclusions:

• The MIR system's effectiveness is significantly impacted by plasma conditions.
• Understanding performance degradation is crucial for optimizing reflectometry techniques.
• A multifrequency MIR system is proposed to overcome current limitations and enhance plasma diagnostics for future fusion devices like KSTAR.