High resolution laser Thomson scattering system with automatic data analysis software platform for diagnosis of the...

Accurate measurements of electron temperature (T_e) and electron density (n_e) are important for understanding the properties of plasma, especially for the low-temperature plasma dominated by the free electrons. In this work, a high resolution laser Thomson scattering (LTS) diagnosis system with a software platform for processing data is established to accurately measure the T_e and n_e in low-temperature plasmas. In this system, a homemade Triple Grating Spectrometer (TGS) is elaborated to suppress the intense stray light and Rayleigh scattering light. The TGS with high etendue (with an f-number of f/3.3) and high spectral resolution (0.07 nm in full-width-half-maximum at 532 nm) allows the LTS system to measure the plasma with the n_e and T_e as low as 1.0 × 10¹⁷ m^-3 and 0.1 eV, respectively. Besides the development of the experimental setup, a software platform is specially designed to automatically process the complicated LTS spectra to determine n_e and T_e in real time during the acquirement of data. The error analyses indicate that the uncertainty of n_e is around 12% and the uncertainty of T_e is about 10% when T_e > 0.2 eV. Using the LTS system, we have successfully measured n_e and T_e in the cascaded arc plasma, nanosecond pulse discharge plasma, and inductively coupled plasma. The results demonstrate that the LTS system has significant potential for the diagnosis of various low temperature plasmas.