Development and application of an ion sensitive probe for helicon plasma diagnostics

Area of Science:

• Plasma Physics
• Diagnostic Techniques

Background:

• Helicon plasma devices require reliable diagnostics.
• Existing probes have limitations in large-diameter systems.

Purpose of the Study:

• To design and implement an Ion Sensitive Probe (ISP) for the PKU Plasma Test (PPT) device.
• To evaluate the performance of the ISP in a large-diameter helicon plasma.
• To investigate the influence of electrode material on ISP diagnostics.

Main Methods:

• Implementation of an ISP in a single-loop antenna helicon plasma discharge.
• Material selection experiments for the ISP electrode.
• Comparative analysis with Langmuir probe measurements.
• Systematic study of plasma parameters (density, temperature) as functions of RF power and magnetic field.

Main Results:

• Tungsten identified as the optimal electrode material for ISP.
• Ion and electron temperatures measured around 1 eV due to electron-ion energy relaxation.
• ISP shows high reliability with maximum deviations of 8% (density) and 12% (electron temperature) compared to Langmuir probes.
• Plasma density increases with RF power; temperatures remain stable.
• Ion temperature response to magnetic field is complex.

Conclusions:

• The ISP is a reliable diagnostic for helicon plasmas, particularly in large-diameter devices.
• The study validates the ISP's accuracy and applicability.
• ISP technology can be extended to other magnetic confinement fusion and plasma processing applications.