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This paper details the design, construction, and analysis of resonant magnetic perturbation (RMP) with 16 in-vessel coils on the HL-3 to investigate the interactions between resonant magnetic perturbations and magnetohydrodynamic instabilities. The toroidal × poloidal = 8 × 2 arrangement allows for a more flexible magnetic field and spectrum shape. The RMP coil was designed as a four-turn double-layer winding. The coils are adopted with a water-cooled hollow copper conductor insulated with a MgO layer and then housed inside a welded stainless steel shell. The thermal and electromagnetic loads of the coil were evaluated by simulation, which meets the requirements. Four power supplies are integrated into the HL-3 system that can provide DC and AC with various waveforms. The maximum DC amplitude is 3 kA, while the AC frequency can reach up to 1 kHz. In the HL-3 H-mode plasmas, an experimental result of edge localized mode (ELM) mitigation with n = 1 RMPs which are oddly paired by 8 RMP coils is also given for the first time in this paper. [ABSTRACT FROM AUTHOR]

• The new XICS diagnostic, which has a poloidal angle for the vertical direction and a tangential angle for the toroidal direction, can simultaneously measure both poloidal velocity and toroidal velocity through data processing. • An XICS system is developed with high spatiotemporal resolution and wide spatial coverage to measure parameters of a large volume and strong shaping plasma through limited diagnostic window conditions. • A series of auxiliary systems for optimizing XICS diagnostic systems. The construction of an X-ray imaging crystal spectrometer (XICS) diagnostic system on the HL-3 tokamak plays a crucial role in measuring core plasma parameter profiles, including ion temperature, electron temperature, rotational velocity, and impurity radiation profiles. This diagnostic system has been specifically designed to provide detailed and accurate data essential for understanding the behavior and characteristics of tokamak plasma. The resonance spectral line (w line of Ar XVII at 3.9494 Å) and its satellites of helium-like argon ions were chosen on the basis of the HL-3 parameter range. A spherically bent quartz crystal (1012) with a lattice constant of 2d = 4.562 Å, a curvature radius of Rc = 3.0 m, and a size of 10 cm (high) × 5 cm (wide) was mounted on an adjustable displacement platform in the XICS system. The position was adjusted in three dimensions (vertical, inclined, rotation) to effectively record the spectra of the helium-like argon ions. The XICS has a tangential angle of 49° for the toroidal direction in the magnetic axis. This layout accounts for 65.6 % of the toroidal rotation velocity component. The XICS system was set at an 11° poloidal angle in the mid-plane to cover a plasma range of 10 cm above to 50 cm below the mid-plane, which corresponds to the q = 1 surface of the HL-3 plasma (elongation κ > 1.8). This XICS layout produced a spectrum with poloidal and toroidal rotational contributions, requiring decoupling through data processing. In general, because the contribution of the poloidal rotation velocity is much smaller than that of the toroidal rotation velocity, it can be ignored. The XICS system offers a spatial resolution of ∼1.5 cm and a temporal resolution of 5–10 ms on the basis of a high-performance PILATUS3 × 900 K detector. The spectral resolution is λ / Δ λ ∼ 4 × 10 4 , which satisfies the experimental measurement requirements. Preliminary results of ion and electron temperature profiles were obtained for the HL-3 tokamak. [ABSTRACT FROM AUTHOR]

• A 13-channel far-infrared (FIR) laser Polarimeter/Interferometer has been designed for the HL-3 tokamak, including eight horizontally-viewing channels and five oblique channels. • The novel structure of support tower allows us to arrange multi-channel light-path on both sides. • Multichannel line-integral electron densities have been successfully measured by the interferometric measurement in 2023, with a time resolution of <1.0 microsecond. The interferometer system will be upgraded to the three-wave based Polarimeter/Interferometer. Aiming to achieve important parameters of the electron density and plasma current density profile, a multi-channel far-infrared (FIR) laser Polarimeter/Interferometer is being developed for HL-3 tokamak by using the formic-acid laser source (HCOOH, λ=432.5 μm). All the 13 probing channels were distributed in two columns, including eight horizontally-viewing channels and five oblique channels. The stainless steel support tower (7.0 m high) was specially designed, and itself novel structure allowed us to arrange the light-paths of horizontal channels and oblique channels on two sides, respectively. Copper corner-cube-reflector (CCR) was mounted in the vacuum vessel to retrace the incident wave. In 2023, multi-channel line-integral electron densities were successfully derived by the interferometric measurement, with a time resolution of 1.0μs, line-integral density resolution of ∼5.0 × 1016/cm2. Right now, the interferometer system is being upgraded to three-wave based Polarimeter/Interferometer, which is able to simultaneously measure the electron density and Faraday rotation angle. [ABSTRACT FROM AUTHOR]

• Preliminary design on multiple shattered pellet injection system for HL-3 has been performed. • In-situ condensation and propellant acceleration technologies are adopted for the dedicated multiple shattered pellet injection system. • Three pellets are prepared by three individual gas supply circuits at the same time, one of which is 7 mm and the others are 5.5 mm in diameter. • Steady-state and transient thermal analysis have been carried out to verifying the design scheme of pellet preparation system. In order to study the physical mechanism and control strategy of disruption mitigation, and to alleviate the destructive effects during disruption, a multiple shattered pellet injection system (multi-SPI) was designed for the HL-3 tokamak. This paper describes the preliminary engineering design of the multi-SPI, and the thermal analysis results of the pellet preparation system. In-situ condensation and propellant acceleration technologies are adopted for the multi-SPI. Three pellets can be prepared at one time and injected individually or simultaneously, one of which is 7 mm and the other two are 5.5 mm in diameter. As the key component of multi-SPI, thermal analysis of the pellet preparation system is given by ANSYS. Results show that the temperature distribution of the heat sink is relatively uniform, and the temperature of standby guns remains lower than the working gas triple point when the other guns were fired. The results verify that the structure design of the pellet preparation system can satisfy the design requirements. [ABSTRACT FROM AUTHOR]