High resolution Thomson scattering system for steady-state linear plasma sources

Area of Science:

• Plasma Physics
• Atomic and Molecular Physics
• Lasers and Optics

Background:

• Accurate measurement of electron temperature (T_e) and density (n_e) is crucial for understanding plasma behavior.
• Traditional Thomson scattering systems face challenges with stray-light reduction, optical transmission, and sampling volume.
• Developing advanced diagnostic techniques is essential for characterizing laboratory plasmas.

Purpose of the Study:

• To develop and validate a high-resolution Thomson scattering system for precise plasma diagnostics.
• To measure radial electron temperature and density profiles in an argon plasma.
• To enhance data acquisition and analysis methods for improved accuracy.

Main Methods:

• Utilized a DC arc source with a lanthanum hexaboride (LaB₆) electrode to generate argon plasma.
• Employed a frequency-doubled Nd:YAG laser (532 nm) and a triple-grating spectrometer with an intensified CCD (ICCD) camera.
• Implemented pixel binning, enlarged slit-width, synchronized camera/laser frequencies, and image subtraction for background noise reduction.
• Applied maximum likelihood estimation for fitting incoherent scattering spectra to determine T_e and n_e.

Main Results:

• Successfully measured electron temperatures exceeding 5 eV and densities of 1.5 × 10¹⁹ m^-3 in argon plasma.
• Demonstrated effective reduction of plasma background influences through image subtraction.
• Achieved improved photon statistics and data quality via optimized system configurations.

Conclusions:

• The developed Thomson scattering system provides accurate radial measurements of T_e and n_e in argon plasma.
• Optimized data acquisition and analysis techniques significantly enhance diagnostic capabilities.
• This methodology offers a robust approach for plasma characterization in various research applications.