Novel data interpretation method for DIII-D divertor retarding field energy analyzer with 3-D particle-in-cell...

Area of Science:

• Plasma Physics
• Fusion Energy Engineering
• Computational Physics

Background:

• The DIII-D fusion device is developing a new retarding field energy analyzer (RFEA) for lower divertor diagnostics.
• The RFEA must withstand extreme heat loads (100 MW/m2 for 5s) and measure ion temperatures (10-200 eV).
• Conventional RFEA data analysis methods may be insufficient due to probe geometry limitations and ion space charge effects.

Purpose of the Study:

• To develop and validate a novel data interpretation process for a new RFEA at DIII-D.
• To improve the accuracy of main ion temperature (Ti) measurements in the divertor target region.
• To address the limitations of simplified 1-D models in extreme fusion environments.

Main Methods:

• Utilizing comprehensive 3-D particle-in-cell (PIC) simulations.
• Incorporating realistic probe geometry and ion space charge effects into the simulations.
• Developing a new data interpretation process based on PIC simulation results.

Main Results:

• A more realistic description of particle propagation within the RFEA cavity was achieved.
• The capability to reconstruct ion energy distribution functions was demonstrated with reasonable consistency.
• The novel PIC-based method offers improved accuracy for RFEA data interpretation.

Conclusions:

• The developed PIC simulation-based data interpretation process is suitable for the new DIII-D RFEA.
• This advanced method overcomes limitations of conventional techniques in extreme divertor conditions.
• The study validates a more robust approach for plasma diagnostic data analysis in fusion research.