Improvement in Thomson scattering diagnostic precision via fitting the multiple-wavenumber spectra simultaneously

Area of Science:

• Plasma Physics
• High Energy Density Physics
• Laser-Plasma Interactions

Background:

• Thomson scattering (TS) is a crucial diagnostic tool for characterizing plasma conditions in high energy density (HED) experiments.
• Accurate measurement of plasma parameters like electron density (n_e) and temperature (T_e) is vital for understanding HED phenomena.

Purpose of the Study:

• To demonstrate and quantify the high precision achievable for multiple plasma parameters using a novel fitting approach for TS spectra.
• To validate the applicability of this advanced TS diagnostic technique across a broad range of plasma conditions and wavenumbers.

Main Methods:

• Utilized Monte Carlo simulations and statistical analysis to fit multiple-wavenumber spectra of ion-acoustic featured Thomson scattering simultaneously.
• Analyzed the fitting precisions for electron density (n_e), electron temperature (T_e), and ion temperature (T_i) under various experimental cases.
• Investigated the chi-square trends for both single- and dual-branch TS spectral fitting.

Main Results:

• Achieved previously unreported high precisions for plasma parameters, including n_e and T_e.
• Demonstrated precisions better than 8% for n_e and 0.5% for T_e under typical conditions on the SG-180kJ laser facility.
• Quantified fitting precisions across different plasma parameter regimes and wavenumbers.

Conclusions:

• The developed method offers significantly enhanced precision for Thomson scattering diagnostics in HED experiments.
• This technique is robust and applicable over a wide range of plasma parameters and wavenumbers, making it a practical advancement.
• The findings pave the way for more accurate and reliable plasma diagnostics in future experimental campaigns.