Vacuum Ultraviolet Spectroscopy at TEXTOR

Biel, W.

doi:10.13182/fst05-a703

Cited by 13 publications

(12 citation statements)

References 23 publications

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“…However, the VUV spectra captured immediately after the argon gas-puff contains spectral emissions from both argon and oxygen . The emission spectral lines are identified using the NIST atomic spectra database 48 and reconfirmed with previous studies in other tokamaks 30,50,51 . As seen from the figure, the Ar 14+ line emissioin at 22.11 nm (2s 2 1 S0 -2s2p 1 P1) has maximum intensity.…”

Section: Experimental Observationssupporting

confidence: 79%

“…In the Ohmic discharges of TEXTOR tokamak, argon puffing experiments are performed and argon transport has been assessed modelling the measured argon spectral line emisisons in the VUV and X-ray range using the STRAHL code. The nature of transport has been found to be purely anomalous at various densitites ranging from 1.4 ~ 3.5 x 10 19 /m 3 in these experiments 30 . Argon is also injected in KSTAR tokmak through gaspuffs.…”

Section: Introductionmentioning

confidence: 54%

“…To start with, the simulations are run by varying the diffusivity only to match the measured Ar 1+ emissivity profile and the intensity ratio of Ar 13+ and Ar 14+ . The convective velocity is neglected during the initial runs, as reported in a few previous studies 30,56 . The impurity source rate is also varied.…”

Section: Methods Of Argon Transport Analysismentioning

confidence: 99%

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Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Shah,

Ghosh,

Patel

et al. 2023

Preprint

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We present experimental results of the trace argon impurity puffing in the Ohmic plasmas of Aditya-U tokamak performed to study the argon transport behaviour. Argon line emissions in visible and Vacuum Ultra Violet (VUV) spectral ranges arising from the plasma edge and core respectively are measured simultaneously. During the experiments, space resolved brightness profile of Ar1+ line emissions at 472.68 nm (3p44s 2P1.5 - 3p44p 2D1.5), 473.59 nm (3p44s 4P2.5 - 3p44p 4P1.5), 476.48 nm (3p44s 2P0.5 - 3p44p 2P1.5), 480.60 nm (3p44s 4P2.5 - 3p44p 4P2.5) are recorded using a high resolution visible spectrometer. Also, a VUV spectrometer has been used to simultaneously observe Ar13+ line emission at 18.79 nm (2s22p 2P1.5 - 2s2p2 2P1.5) and Ar14+ line emission at 22.11 nm (2s2 1S0 - 2s2p 1P1). The diffusivity and convective velocity of Ar are obtained by comparing the measured radial emissivity profile of Ar1+ emission and the line intensity ratio of Ar13+ and Ar14+ ions, with those simulated using the impurity transport code, STRAHL. Argon diffusivities ~ 12 m2/s and ~ 0.3 m2/s have been observed in the edge (ρ > 0.85) and core region of the Aditya-U, respectively. The diffusivity values both in the edge and core region are found to be higher than the neo-classical values suggesting that the argon impurity transport is mainly anomalous in the Aditya-U tokamak. Also, an inward pinch of ~ 10 m/s mainly driven by Ware pinch is required to match the measured and simulated data. The measured peaked profile of Ar density suggests impurity accumulation in these discharges.

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Section: Experimental Observationssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 54%

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Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Shah,

Ghosh,

Patel

et al. 2023

Preprint

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“…JT-60SA will be equipped with two VUV survey spectrometers, one observing the plasma from an equatorial port to monitor light and metal impurities, and one positioned on one upper port with a vertical line of sight of the divertor including a relay mirror system (figure 11). This last one will be a double imaging spectrometer derived from the system previously installed in TEXTOR [21]. The expected spatial resolution of ∼0.1 m is enough to resolve the relative contribution of the various intrinsic (C, O, Ni, Cr, etc) and extrinsic (N, Ar, Ne, Kr) impurities coming from the outer leg, the x point and the inner leg of the separatrix, for the study of the plasma-divertor detachment physics [22].…”

Section: Plasma Diagnosticsmentioning

confidence: 99%

Completion of JT-60SA construction and contribution to ITER

et al. 2022

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Construction of the JT-60SA tokamak was completed on schedule in March 2020. Manufacture and assembly of all the main tokamak components satisfied technical requirements, including dimensional accuracy and functional performances. Development of the plasma heating systems and diagnostics have also progressed, including the demonstration of the favourable electron cyclotron range of frequency (ECRF) transmission at multiple frequencies and the achievement of long sustainment of a high-energy intense negative ion beam. Development of all the tokamak operation control systems has been completed, together with an improved plasma equilibrium control scheme suitable for superconducting tokamaks including ITER. For preparation of the tokamak operation, plasma discharge scenarios have been established using this advanced equilibrium controller. Individual commissioning of the cryogenic system and the power supply system confirmed that these systems satisfy design requirements including operational schemes contributing directly to ITER, such as active control of heat load fluctuation of the cryoplant, which is essential for dynamic operation in superconducting tokamaks. The integrated commissioning (IC) is started by vacuum pumping of the vacuum vessel and cryostat, and then moved to cool-down of the tokamak and coil excitation tests. Transition to the super-conducting state was confirmed for all the TF, EF and CS coils. The TF coil current successfully reached 25.7 kA, which is the nominal operating current of the TF coil. For this nominal toroidal field of 2.25 T, ECRF was applied and an ECRF plasma was created. The IC was, however, suspended by an incident of over current of one of the superconducting equilibrium field coil and He leakage caused by insufficient voltage holding capability at a terminal joint of the coil. The unique importance of JT-60SA for H-mode and high-β steady-state plasma research has been confirmed using advanced integrated modellings. These experiences of assembly, IC and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.

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“…For this purpose, usually the first resonance lines have been measured though visible lines are useful for divertor spectroscopy. Therefore, VUV spectroscopy becomes important for passive plasma spectroscopy and the resonance lines from typical intrinsic impurities such as carbon, oxygen and iron have been routinely measured in the VUV region in many magnetic fusion devices [2][3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

High-Resolution VUV Spectra of Carbon, Neon and Argon in a Wavelength Range of 250 to 2300 Å for Plasma Diagnostics Observed with a 3 m Normal Incidence Spectrometer in LHD

Katai

Morita

Goto

2007

Plasma and Fusion Research

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Intrinsic impurities have been much reduced in toroidal fusion devices through the development of several wall-conditioning techniques as well as by the use of carbon materials in the first wall and divertor plates. Impurity elements useful for passive plasma spectroscopy have been then extremely limited. At present, only carbon is a subject for spectroscopic diagnostics in most discharges except for fuel atoms. The use of rare gas as a brighter light source is a method to overcome the present difficulty in passive spectroscopy. Recently, rare gases have also been used for edge cooling to reduce the divertor heat flux. Therefore, high-resolution spectra (∆λ ∼ 0.2 Å) from neon and argon in a 250 to 2300 Å wavelength range have been measured using a 3 m normal incidence spectrometer in Large Helical Device (LHD) and the measured spectra were precisely analyzed. The VUV spectra of carbon, neon and argon are presented for spectroscopic use and their wavelengths are tabulated with their relative intensities. The spectral profiles of almost all the spectral lines measured here are formed by the Doppler broadening and self-absorption processes. The Doppler broadening of neon and argon spectra are plotted against the ionization energies and Doppler spectra from carbon lines are presented. The self-absorption spectra of the hydrogen Lyman-α line, which are found in the LHD high-density discharge, are also presented and the neutral density is analytically estimated.

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Vacuum Ultraviolet Spectroscopy at TEXTOR

Abstract: Spectroscopy in fusion experiments is an important tool to identify impurities in the plasma

Cited by 13 publications

References 23 publications

Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Completion of JT-60SA construction and contribution to ITER

High-Resolution VUV Spectra of Carbon, Neon and Argon in a Wavelength Range of 250 to 2300 Å for Plasma Diagnostics Observed with a 3 m Normal Incidence Spectrometer in LHD

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