Design of a Lyman-Alpha-Based BES for edge plasma density diagnosing on the HL-2A tokamak

Zhou, Yan; Yu, Yijun; Ke, Rui; Jiang, Wenzhe; Xu, M.; Xiao, Chijie; Cheng, Yu; Li, Z.J.; Li, B.L.; Wang, Z.H.; Li, J.Q.; Duan, X.R.; Ye, M.Y.

doi:10.1016/j.fusengdes.2021.112911

Cited by 3 publications

(9 citation statements)

References 30 publications

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“…The base pressure is 10 −5 Pa, which is enough to test the Raman 𝛼 beam-emission-spectroscopy diagnostics developed for density measurement on HL-2A tokamak. This system will collect the 121-nm vacuum ultraviolet radiation [14]. 15 magnetic coils can generate a magnetic field with a maximal strength of 0.2 T. The currents of the coils are independently adjustable, allowing us to modify the field to a uniform axial field, converging field, diverging field, or cusp field for different experiments [15].…”

Section: Experiments Setupmentioning

confidence: 99%

The first plasma in a newly constructed linear device for plasma turbulence research

Yu,

Xiao,

Liu

et al. 2024

J. Inst.

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Parameters of the first plasma in a newly built middle-size multi-functional linear plasma device named LEAD (Linear Experimental Advanced Device) were presented. The LEAD device is built to serve as a multi-purpose laboratory plasma experiment platform for various topics, including plasma turbulence, plasma-material interaction, and other fundamental plasma physics. This device is also useful for testing new diagnostic systems. It will be complementary to the HL-2A/HL-3 tokamaks in Southwestern Institute of Physics. The plasma was generated by a large-area helicon plasma source with a multi-ring antenna driven by a 13.56 MHz, 5 kW radio frequency (RF) power source. Argon plasma parameters were measured by a Langmuir probe in different external parameters including RF power, axial magnetic field, and neutral pressure. The threshold power for helicon mode transition is empirically confirmed to be 180 W. Steady-state argon plasma with a density of higher than 1019 m-3 was generated when RF power reached 3 kW. Plasma parameters are crucially influenced by the axial magnetic field. With a weak magnetic field, the radial density profile is Gaussian-like. However, with a stronger magnetic field, shear and reversion of azimuthal rotation velocity reversion appear, resulting in a hollow-shaped density profile. When further increasing the magnetic field, plasma density decreases. Steady-state plasma discharges were achieved under a wide range of argon neutral pressure from 0.1 Pa to over 10 Pa. With increasing neutral pressure, plasma density increases to its maximum at 2.5 Pa and then drops, while electron temperature drops monotonically.

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Section: Experiments Setupmentioning

confidence: 99%

The first plasma in a newly constructed linear device for plasma turbulence research

Yu,

Xiao,

Liu

et al. 2024

J. Inst.

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“…Compared with the Doppler-shifted Balmer-alpha line (n = 3→2, λ 0 = 656.10 nm) collected by conventional BES, LyBES observes the Doppler-shifted Lyman-alpha line (n = 2→1, λ 0 = 121.53 nm) which lies in the vacuum ultraviolet band. The wavelength of the targeted Doppler-shifted Lyman-alpha line is ~121.98 nm on HL-2A [17,18], with the chosen line of sight. The viewing area of the developing LyBES system on HL-2A will cover plasma from R = 1960 mm to R = 2026 mm, with an average spatial resolution of 3.3 mm.…”

Section: The Lybes Diagnostic System On Hl-2amentioning

confidence: 99%

“…Compared with the conventional visible light BES diagnostic, LyBES could have a theoretically improved spatial resolution of several millimeters while maintaining the temporal resolution of 1 μs, which results mainly from the short lifetime of the Lyman-alpha line (n = 2→1, λ 0 = 121.53 nm). Furthermore, LyBES could have greater signal intensity than that of visible light BES, benefited from a larger transition rate, state density, and fluctuation sensitivity of the Lyman-alpha line [16][17][18]. However, there is no further progress reported on LyBES, probably owing to the greater technical and engineering difficulties of vacuum ultraviolet spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…However, there is no further progress reported on LyBES, probably owing to the greater technical and engineering difficulties of vacuum ultraviolet spectroscopy. In recent years, for the first time, a novel edge LyBES system has been developed for the HL-2A tokamak, and the detailed calculations and design of LyBES have been completed [17,18]. It is to be noted that the LyBES was called LAB previously [17,18], which refers to the same diagnostic.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, for the first time, a novel edge LyBES system has been developed for the HL-2A tokamak, and the detailed calculations and design of LyBES have been completed [17,18]. It is to be noted that the LyBES was called LAB previously [17,18], which refers to the same diagnostic.…”

Section: Introductionmentioning

confidence: 99%

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Progress of Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic on the HL-2A tokamak

ZHOU 周,

YU 余,

XU 许

et al. 2024

Plasma Sci. Technol.

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An edge Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic, using a heating NBI (neutral beam injection) system, is currently under development on the HL-2A tokamak. The 20-channel edge LyBES, which is intended to measure the density fluctuation in plasma edge (from R = 1960 mm to R = 2026 mm) with an improved spatial resolution of 3.3 mm, is a complement to the existing conventional beam emission spectroscopy (BES) diagnostic. In this article, we introduce the progress of LyBES diagnostic, including the collection optics, the monochromator, and the detector system. The reflectance of the collection mirrors is measured to be ~82% at 122 nm, and the aberration geometrical radius of the collection optics is tested to be ~150 μm in the aimed area. The linear dispersion of the LyBES monochromator is designed to be ~0.09 nm mm−1. The bandwidth of the detector system with the 5×107 V A−1 preamplifier gain is measured to be ~280 kHz, and the peak-to-peak noise of the detector system is tested to be ~16 mV. The finalized design, components development and testing of the LyBES diagnostic have been completed at present, and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2A campaign.

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A newly constructed Linear Experimental Advanced Device LEAD

Wang

Zheng

Wang

et al. 2023

Fusion Engineering and Design

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Design of a Lyman-Alpha-Based BES for edge plasma density diagnosing on the HL-2A tokamak

Cited by 3 publications

References 30 publications

The first plasma in a newly constructed linear device for plasma turbulence research

The first plasma in a newly constructed linear device for plasma turbulence research

Progress of Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic on the HL-2A tokamak

A newly constructed Linear Experimental Advanced Device LEAD

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