Comparative study between the reflective optics and lens based system for microwave imaging system on KSTAR.

Area of Science:

• Plasma physics
• Fusion energy research
• Diagnostic techniques

Background:

• Two-dimensional microwave imaging diagnostics, including electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR), are essential for investigating magnetohydrodynamics instabilities and turbulence in magnetically confined plasmas.
• These systems rely on large optical components to gather radiation, with designs typically falling into reflective or refractive categories.
• Existing systems on tokamaks like TEXTOR, DIII-D, ASDEX-U, and KSTAR utilize either reflective or refractive optics, each presenting unique challenges such as standing wave effects and optical aberrations.

Purpose of the Study:

• To conduct a comparative analysis of reflective and refractive optical systems used in microwave imaging diagnostics.
• To inform the design of a new microwave imaging reflectometry (MIR) system for the Korea Superconducting Tokamak Advanced Research (KSTAR) facility.
• To evaluate the advantages and disadvantages of each optical design concerning plasma diagnostics.

Main Methods:

• Review and comparison of existing reflective and refractive optical designs for ECEI and MIR systems.
• Analysis of optical aberrations and standing wave issues associated with each system type.
• Application of comparative findings to the specific requirements for a KSTAR MIR system design.

Main Results:

• Reflective and refractive optical systems exhibit distinct trade-offs regarding performance and implementation.
• Understanding these trade-offs is critical for mitigating issues like standing waves and optical aberrations.
• The study provides a basis for selecting the optimal optical configuration for advanced plasma diagnostics.

Conclusions:

• The choice between reflective and refractive optics significantly impacts the performance of microwave imaging diagnostics.
• A thorough comparative study is necessary for optimizing the design of next-generation systems like the KSTAR MIR.
• This research contributes to the advancement of plasma confinement and turbulence studies through improved diagnostic capabilities.