Charge exchange spectroscopy using spatial heterodyne spectrometer in the large helical device

Area of Science:

• Plasma Physics
• Spectroscopy
• Fusion Energy Research

Background:

• Accurate measurement of plasma properties like toroidal flow velocity and ion temperature is crucial for fusion energy research.
• Charge exchange spectroscopy is a key diagnostic technique, but conventional dispersive spectrometers have limitations.

Purpose of the Study:

• To explore the application of a spatial heterodyne spectrometer (SHS) for measuring C6+ impurity ion toroidal flow velocity (Vf) and ion temperature (TC).
• To compare the performance of SHS with a conventional dispersive spectrometer (DS) for these measurements.

Main Methods:

• Utilized a spatial heterodyne spectrometer (SHS) with specific aperture size and etendue.
• Extrapolated the instrumental width (IW) of the SHS.
• Employed charge exchange spectroscopy to measure Vf and TC of C6+ ions.
• Compared SHS measurements with those obtained from a conventional dispersive spectrometer (DS).

Main Results:

• The SHS exhibited an extrapolated instrumental width (IW) of 0.09 nm, which is significantly narrower than the 0.17 nm IW of the conventional DS.
• The Vf and TC measurements obtained using SHS showed good agreement with the results from the DS.
• The SHS demonstrated a higher etendue and larger aperture size compared to the DS.

Conclusions:

• Spatial heterodyne spectrometers (SHS) are a viable and potentially superior alternative to dispersive spectrometers for measuring plasma toroidal flow velocity and ion temperature.
• The narrower instrumental width of SHS leads to more precise measurements.
• SHS technology holds promise for advancing plasma diagnostics in fusion research.