Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamak

Soukhanovskii, V.; McLean, A.G.; Allen, S. L.

doi:10.1063/1.4891600

Cited by 7 publications

(1 citation statement)

References 16 publications

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“…Hence there is a need for databases of tabulated spectral emission lines that have been clearly identified in magnetically confined plasmas. At present, there exists in the literature a limited number of spectral line surveys covering different wavelength ranges [4,[9][10][11]. In most cases such data tabulate intrinsic, vacuum wall deposited elements, and/or commonly injected elements, e.g., helium, lithium, boron, carbon, nitrogen, oxygen, neon, aluminium, iron or chromium.…”

Section: Introductionmentioning

confidence: 99%

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

McCarthy¹,

Tamura

Combs

et al. 2018

Phys. Scr.

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43 spectral emission lines from F-like to Li-like sulphur ions have been identified in the wavelength range from 17.5 to 50 nm in spectra obtained following tracer injection into plasmas created in a magnetically confined plasma device, the stellarator TJ-II. Plasmas created and maintained in this heliac device with electron cyclotron resonance heating achieve central electron temperatures and densities up to 1.5 keV and 8×10 18 m −3 , respectively. Tracer injections were performed with 6×10 16 atoms of sulphur contained within ∼300 μm diameter polystyrene capsules, termed tracer encapsulated solid pellets, using a gas propulsion system to achieve velocities between 250 and 450 m s −1 . Once ablation of the exterior polystyrene shell by plasma particles is completed, the sulphur is deposited in the plasma core where it is ionized up to S +13 and transported about the plasma. In order to aid line identification, which is made using a number of atomic line emission databases, spectra are collected before and after injection using a 1 m focal length normal incidence spectrometer equipped with a CCD camera. This work is motivated by the need to clearly identify sulphur emission lines in the vacuum ultraviolet range of magnetically confined plasmas, as sulphur x-ray emission lines are regularly observed in both tokamak and stellarator plasmas.

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Section: Introductionmentioning

confidence: 99%

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

McCarthy¹,

Tamura

Combs

et al. 2018

Phys. Scr.

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Real-time radiative divertor feedback control development for the NSTX-U tokamak using a vacuum ultraviolet spectrometer

Soukhanovskii

Kaita

Stratton

2016

Review of Scientific Instruments

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A radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature T estimated spectroscopically in real time will be used as a control parameter. A vacuum ultraviolet spectrometer McPherson Model 251 with a fast charged-coupled device detector is developed for temperature monitoring between 5 and 30 eV, based on the Δn = 0, 1 line intensity ratios of carbon, nitrogen, or neon ion lines in the spectral range 300-1600 Å. A collisional-radiative model-based line intensity ratio will be used for relative calibration. A real-time T-dependent signal within a characteristic divertor detachment equilibration time of ∼10-15 ms is expected.

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Application of portable near-infrared spectrometer to Heliotron J plasma diagnostics

Kado

Iwata

Kanazawa

et al. 2018

Review of Scientific Instruments

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A simple near-infrared (NIR) spectrometer with a wavelength range of 898–2130 nm has recently been applied to diagnose Heliotron J plasmas. It adopts a symmetrical crossed Czerny–Turner mount equipped with a thermoelectrically cooled 512 channel InGaAs linear sensor. Reciprocal linear dispersion was deduced to 96.37 nm/mm at the center of the detector. External filters can be inserted into the path of the collection optics to reject second-order spectra, as needed. Absolute intensity calibration was performed together with a visible spectrometer using a tungsten halogen lamp, and the effect of the transmittance fringe in the visible region of the applied long-pass filter on the NIR calibration was investigated. The intended application of the NIR spectrometer includes extending the wavelength region of a spectral monitor to less contaminated regions for Heliotron J plasma studies. In preliminary measurements, we observed the Paschen series for the hydrogen pellet injection plasma and two atomic helium lines, i.e., 2S-2P singlet and triplet lines, in helium gas puffing experiments. A continuum spectrum in this regime that is attributable to black-body radiation from hot spots on the plasma-facing components was identified. In addition, this may also be used to monitor background radiation in the YAG-Thomson scattering signals near 1064 nm.

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Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamak

Cited by 7 publications

References 16 publications

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

Real-time radiative divertor feedback control development for the NSTX-U tokamak using a vacuum ultraviolet spectrometer

Application of portable near-infrared spectrometer to Heliotron J plasma diagnostics

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