Development of a 3-D visible limiter imaging system for the HSX stellarator

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Diagnostic Development

Background:

• Understanding plasma-wall interactions is crucial for fusion reactor design.
• The complex 3D geometry of stellarators like HSX presents challenges for diagnostics.
• Previous methods for studying limiter plasma interaction in HSX were limited.

Purpose of the Study:

• To develop and implement a novel visible camera diagnostic for the HSX stellarator.
• To investigate the plasma interaction with the HSX limiter.
• To measure particle fluxes of hydrogen and carbon species.

Main Methods:

• Designed and installed a custom mirror/lens system to overcome geometric viewing constraints.
• Developed a specialized support structure for robust and repeatable optical system positioning.
• Calibrated the camera system and used Hα and C-III filters to determine photon fluxes, converting them to particle fluxes using an S/XB coefficient.

Main Results:

• Successfully obtained measurements of hydrogen and C-III photon fluxes at the HSX plasma edge.
• Determined the characteristic penetration lengths for hydrogen and C-III species.
• The measured hydrogen penetration length (λiz) showed good agreement with 1D model predictions.

Conclusions:

• The developed camera diagnostic is effective for studying plasma-limiter interactions in complex stellarator geometries.
• The measurements provide valuable data for validating plasma transport models.
• This diagnostic advancement contributes to the understanding and optimization of fusion devices.