Abstract:
Background The study of multi-scale turbulence and related anomalous transport under high-performance plasma operation remains an important topic in the research of magnetic confinement fusion. The parameter range of plasmas in the tokamak experiment determines that far-infrared laser collective scattering is the optimal diagnostic method for multi-scale turbulence diagnostics.
Purpose This paper discusses the overall design parameters of the diagnostic system and provide a detailed introduction to the design of the windows for the multi-scale turbulence collective scattering (MSTCS) diagnostic system on the HL-3 Tokamak.
Methods The laser beam entrance window of the MSTCS diagnostic system is located in the mid-plane port #6 of the HL-3 tokamak, and the scattered light beams exit from the windows in the mid-plane port #12. The design aspects of the windows include the material selection, clear aperture calculation, window thickness design, mechanical design, and surface quality requirements. Several interrelated factors need to be considered in the design process. These include the diagnostic wavenumber range, wavenumber resolution, wavenumber purity of the scattering data, laser beam transmission coefficients, and the requirements for vacuum sealing and safety.
Results On the basis of these considerations, a corresponding design scheme was formulated. The technical details of the analysis and design process as well as the design results are presented.
Conclusions The MSTCS diagnostic system has been successfully installed on HL-3, and preliminary experimental data confirm the vacuum safety and optical performance of the diagnostic windows, thereby validating the overall design.