Refractive and relativistic effects on ITER low field side reflectometer design.

Area of Science:

• Plasma physics
• Fusion energy research
• Wave propagation

Background:

• The International Thermonuclear Experimental Reactor (ITER) requires advanced diagnostics for plasma measurement.
• Low field side reflectometry is crucial for diagnosing plasma edge and scrape-off layer (SOL) conditions.
• Relativistic electron temperatures and wave refraction pose significant challenges for reflectometer design.

Purpose of the Study:

• To investigate the impact of relativistic electron temperatures and wave refraction on ITER's low field side reflectometer.
• To quantify the characteristics of reflected millimeter waves under simulated ITER conditions.
• To evaluate the influence of antenna design parameters on reflectometer performance.

Main Methods:

• Utilized GENRAY, a 3D ray tracing code, for wave propagation simulation.
• Simulated a representative ITER operating scenario.
• Analyzed reflected wave characteristics as a function of antenna height, diameter, and radial position.

Main Results:

• Quantified millimeter wave reflection characteristics, considering relativistic effects and refraction.
• Reported results for O- and X-mode polarizations.
• Identified the impact of antenna design parameters on measurement accuracy.

Conclusions:

• 3D ray tracing is effective for analyzing reflectometer performance under challenging ITER conditions.
• Antenna design parameters significantly influence the reliability of edge/SOL plasma measurements.
• The findings provide crucial insights for the optimal design of ITER's low field side reflectometer.