Modifications to the synthetic aperture microwave imaging diagnostic

Area of Science:

• Plasma physics
• Fusion energy research
• Microwave diagnostics

Background:

• The synthetic aperture microwave imaging diagnostic has been operational on the Mega Ampere Spherical Tokamak (MAST) experiment since 2011.
• It has successfully provided the first 2D images of B-X-O mode conversion windows.
• The diagnostic demonstrated the feasibility of 2D Doppler back-scattering (DBS) experiments.

Purpose of the Study:

• To modify and enhance the synthetic aperture microwave imaging diagnostic.
• To enable new measurement capabilities including pitch angle profile measurements and O and X mode separation.
• To facilitate continuous acquisition of 2D DBS data.

Main Methods:

• Utilizing field programmable gate arrays (FPGAs) for data processing.
• Implementing modifications based on operational experience from MAST.
• Installing and configuring the enhanced diagnostic on the National Spherical Torus Experiment Upgrade (NSTX-U).

Main Results:

• The enhanced diagnostic enables pitch angle profile measurements.
• It allows for O and X mode separation.
• Continuous acquisition of 2D DBS data is now possible.

Conclusions:

• The modifications have significantly improved the capabilities of the synthetic aperture microwave imaging diagnostic.
• The enhanced diagnostic is a valuable tool for fusion plasma research, now operational on both MAST and NSTX-U.
• The system's advancements support detailed plasma diagnostics for future fusion energy development.