Nd:YAG laser Thomson scattering diagnostics for a laboratory magnetosphere

Area of Science:

• Plasma Physics
• Fusion Energy Research

Background:

• The RT-1 device aims to explore high-beta plasma formation.
• Understanding plasma parameters is crucial for fusion energy development.

Purpose of the Study:

• Develop and implement a new Nd:YAG laser Thomson scattering (TS) system.
• Investigate the mechanism of high-beta plasma formation in the RT-1 device.

Main Methods:

• Utilized a 1.2-J Nd:YAG laser TS system with a 90° scattering angle.
• Employed a bright optical system with a 260-mm diameter collection window and 300-mm diameter lenses for low-density measurements.
• Detected scattered light using a polychromator after transfer via lenses and an optical fiber bundle.
• Performed Raman scattering for optical alignment and absolute calibration.

Main Results:

• Successfully measured electron temperatures (T_e) ranging from 10 eV to 50 keV and electron densities (n_e) exceeding 1.0 × 10¹⁷ m^-3.
• Recorded T_e = 72.2 eV and n_e = 0.43 × 10¹⁶ m^-3 for the coil-supported case.
• Measured T_e = 79.2 eV and n_e = 1.28 × 10¹⁶ m^-3 for the coil-levitated case near the magnetospheric plasma inner edge.

Conclusions:

• The developed TS system is effective for diagnosing plasma parameters in the RT-1 device.
• The measurements provide insights into high-beta plasma formation mechanisms under different coil configurations.