Hydrogen emission location, temperature and inward velocity in the peripheral helical plasma as observed with plasma polarization spectroscopy

Iwamae, Atsushi; Sakaue, A.; Neshi, Nobuhiro; Yanagibayashi, Jun; Hasuo, Masahiro; Goto, M.; Morita, S.

doi:10.1088/0953-4075/43/14/144019

Cited by 10 publications

(14 citation statements)

References 16 publications

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“…Once the U CX is obtained, the spatial and velocity distribution of the hot atoms n H hot (R, v) is calculated with the same form to Eqs. (A1) and (8).…”

Section: Appendix: Transport Calculation Of Hot Atoms Including Multimentioning

confidence: 97%

“…6 Iwamae et al combines a polarization-resolved spectroscopic technique with the Zeeman split analysis method for increasing the measurement accuracies. 7,8 They have measured the Balmer-a line shape for large helical device (LHD) with eight LOSs with their polarization resolved. They determined the emission locations of the Balmer-a line from the polarization dependence of the line shapes by the Zeeman split.…”

Section: Introductionmentioning

confidence: 99%

“…The reported emission locations of the Balmer-a lines are almost outside the last closed flux surface (LCFS) of LHD. 8 A relation between the Balmer-a line intensity and the ionization flux of the atoms is calculated by a collisionalradiative model, which has been developed by Sawada et al [9][10][11] The emission intensity ratios of the Balmer-a, -b, and -c lines have been predicted from the calculation to have a dependence on the electron temperature and density at the emission locations. A plasma diagnostic method using the emission intensity ratios have also been proposed.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen transport diagnostics by atomic and molecular emission line profiles simultaneously measured for large helical device

et al. 2013

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We observe the Balmer-a, -b, and -c lines of hydrogen atoms and Q branches of the Fulcher-a band of hydrogen molecules simultaneously with their polarization resolved for large helical device. From the fit including the line splits and the polarization dependences by the Zeeman effect, the emission locations, intensities, and the temperatures of the atoms and molecules are determined. The emission locations of the hydrogen atoms are determined outside but close to the last closed flux surface (LCFS). The results are consistent with a previous work (Phys. Plasmas 12, 042501 (2005)). On the other hand, the emission locations of the molecules are determined to be in the divertor legs, which is farer from those of the atoms. The kinetic energy of the atoms is 1 $ 20 eV, while the rotational temperature of molecules is $0.04 eV. Additionally, substantial wings, which originate from high velocity atoms and are not reproduced by the conventional spectral analysis, are observed in the Balmer line profiles. We develop a one-dimensional model to simulate the transport of the atoms and molecules. The model reproduces the differences of the emission locations of the atoms and molecules when their initial temperatures are assumed to be 3 eV and 0.04 eV, respectively. From the model, the wings of the Balmer-a line is attributed to the high velocity atoms exist deep inside the LCFS, which are generated by the charge exchange collisions with hot protons there. V C 2013 American Institute of Physics. [http://dx.

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“…Once the U CX is obtained, the spatial and velocity distribution of the hot atoms n H hot (R, v) is calculated with the same form to Eqs. (A1) and (8).…”

Section: Appendix: Transport Calculation Of Hot Atoms Including Multimentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrogen transport diagnostics by atomic and molecular emission line profiles simultaneously measured for large helical device

et al. 2013

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“…A multiple LOSs measurement with this technique has been performed by Shikama et al [8]. Iwamae et al have demonstrated the emission location measurement of the hydrogen atoms for the Large Helical Device (LHD) with an aid of the polarization-resolved spectroscopic technique [9,10].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Atomic and Molecular Emission Locations and Intensities in the LHD Edge Plasma Determined from Simultaneously Observed Polarization Spectra

Fujii

Sawada

Goto

et al. 2015

Plasma and Fusion Research

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We observed polarization-resolved emission spectra of the Balmer-α,-β, and-γ lines of hydrogen atoms and the Q branches of the Fulcher-α band of hydrogen molecules simultaneously with six lines of sight in a poloidal cross section of the Large Helical Device (LHD). From the fit of the spectra including the line splits and their polarization dependence due to the Zeeman effect, we determined the emission locations, intensities and temperatures of the atoms and molecules. The determined emission locations of the hydrogen atoms were just outside the last closed flux surface and the intensities showed small dependence on the location. The emission locations of the molecules were rather around the divertor legs and their emission intensities showed location dependences. The determined atomic temperature was about 1 eV and the molecular rotational temperature was 0.04∼0.07 eV, both of which showed no systematic dependence on the location within the experimental accuracy.

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“…Molecular and atomic hydrogen is ionized mainly in peripheral regions of magnetic fusion plasma, so their ionization flux is highest along plasma edges. [1][2][3] Nevertheless, through charge exchange collisions with hot protons, some fraction of the atoms penetrates deep inside the plasma as neutral hydrogen and acts as a source of electrons and protons in the core region. [4][5][6] We recently investigated detailed line profiles of Balmer series emissions from high temperature plasmas generated in the Large Helical Device (LHD) 7 and found that emissions from high temperature atoms in the core region of the plasma appear in the far wing portions of the profile, while those from the peripheral region appear in the central part.…”

Section: Introductionmentioning

confidence: 99%

Development of a high dynamic range spectroscopic system for observation of neutral hydrogen atom density distribution in Large Helical Device core plasma

Fujii

Atsumi

Watanabe

et al. 2014

Review of Scientific Instruments

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We report development of a high dynamic range spectroscopic system comprising a spectrometer with 30% throughput and a camera with a low-noise fast-readout complementary metal-oxide semiconductor sensor. The system achieves a 10 6 dynamic range (∼20 bit resolution) and an instrumental function approximated by a Voigt profile with Gauss and Lorentz widths of 31 and 0.31 pm, respectively, for 656 nm light. The application of the system for line profile observations of the Balmer-α emissions from high temperature plasmas generated in the Large Helical Device is also presented. In the observed line profiles, emissions are detected in far wings more than 1.0 nm away from the line center, equivalent to neutral hydrogen atom kinetic energies above 1 keV. We evaluate atom density distributions in the core plasma by analyzing the line profiles.

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Hydrogen emission location, temperature and inward velocity in the peripheral helical plasma as observed with plasma polarization spectroscopy

Cited by 10 publications

References 16 publications

Hydrogen transport diagnostics by atomic and molecular emission line profiles simultaneously measured for large helical device

Hydrogen transport diagnostics by atomic and molecular emission line profiles simultaneously measured for large helical device

Hydrogen Atomic and Molecular Emission Locations and Intensities in the LHD Edge Plasma Determined from Simultaneously Observed Polarization Spectra

Development of a high dynamic range spectroscopic system for observation of neutral hydrogen atom density distribution in Large Helical Device core plasma

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