Design and initial operation of a two-color soft x-ray camera system on the Compact Toroidal Hybrid experiment

Area of Science:

• Plasma Physics
• Fusion Energy Research

Background:

• The Compact Toroidal Hybrid (CTH) experiment is a five-field period current-carrying stellarator.
• Understanding plasma behavior, including electron temperature profiles and magnetohydrodynamic (MHD) activity, is crucial for fusion energy development.

Purpose of the Study:

• To develop and implement a multi-camera soft x-ray diagnostic system for the CTH experiment.
• To measure equilibrium electron temperature profiles and temperature fluctuations caused by MHD activity.

Main Methods:

• Utilized a multi-camera system with three cameras, each equipped with two 20-channel diode arrays.
• Employed two different beryllium filter thicknesses (1.8 μm and 3.0 μm) for dual-color measurements.
• Measured soft x-ray emissions to determine electron temperatures between 50 eV and 200 eV.

Main Results:

• Successfully developed a diagnostic capable of measuring electron temperature profiles and fluctuations.
• Observed temperature perturbations associated with sawtooth oscillations in hybrid discharges.
• Discussed the impact of plasma asymmetry and impurity line radiation on diagnostic design and measurements.

Conclusions:

• The developed soft x-ray diagnostic is effective for characterizing electron temperature in the CTH stellarator.
• The diagnostic provides valuable data for studying MHD activity and plasma dynamics.
• Further analysis of temperature perturbations can enhance understanding of plasma stability in current-carrying stellarators.