Scanning multiple collector electrostatic analyzer with application to plasma potential measurement.

Area of Science:

• Plasma Physics
• Diagnostic Techniques
• Electrostatic Analysis

Background:

• Accurate measurement of plasma potential is crucial for understanding magnetically confined plasmas.
• Previous diagnostic methods, like feedback approaches, had limitations in resolution and facility.
• Heavy ion probe diagnostics require wide entrance slits due to low signal levels.

Purpose of the Study:

• To develop and validate a novel method for precise plasma potential measurement using collector electrodes.
• To enhance the resolution and efficiency of energy measurements in heavy ion probe diagnostics.
• To compare experimental results with theoretical predictions for an ideal electrostatic energy analyzer.

Main Methods:

• Utilized three collector electrodes positioned on the focal plane of a parallel-plate electrostatic energy analyzer.
• Designed an exit slit matched to a large inlet slit via a magnification ratio.
• Conducted bench tests using a 5 kV, monoenergetic K+ beam to evaluate scanning capability and precision (ΔV/V ≈ ±10⁻³).

Main Results:

• Achieved high precision (ΔV/V ≈ ±10⁻³) for energy measurements, sufficient for resolving plasma potential.
• Observed a sharply peaked, nearly triangular profile on the center collector, indicating enhanced resolution.
• Compared scan results at various entrance angles with predictions, validating the instrument model.

Conclusions:

• The developed collector electrode system provides a precise and enhanced resolution method for plasma potential measurements.
• This technique offers greater facility compared to prior feedback-based approaches for heavy ion probe diagnostics.
• The results confirm the viability of the electrostatic energy analyzer design for advanced plasma studies.