Development of multiwavelength-range fine-resolution spectrometer for hydrogen emissions and its application to large helical device periphery plasmas

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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“…16,17 Here, we report on the measurement results of these emission lines for LHD. Figure 1 shows a top view of LHD.…”

Section: Introductionmentioning

confidence: 97%

“…16,17 A schematic illustration of the spectrometer is shown in Figure 4(a). The edges of the optical fibers line along the slit with a pitch of 500 lm.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2013

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“…For the purpose of further improving this technique, we recently demonstrated a method to observe several emission spectra of hydrogen atoms and molecules simultaneously with developing a multi-wavelength highresolution (MH) spectrometer [16,17]. From the observed Zeeman splits of the atomic and molecular lines, we have shown the difference of the atomic and molecular emission locations in the LHD [18].…”

Section: Introductionmentioning

confidence: 99%

“…With this spectrometer, high resolution spectra of the Balmer-α, -β, and -γ lines of hydrogen atoms and the Fulcher-α band Q1 lines of v = v = 0 and 2 transitions of hydrogen molecules are simultaneously observed, where v and v are vibronic quantum numbers of the upper and lower states of the transition, respectively. Details of the MH spectrometer are described in [16][17][18].…”

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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“…4 (a), (b) and (c), respectively, with the open circles. For the observation, a radial viewing chord passing through the peripheral region was chosen and the multi-wavelength-range fine-resolution spectrometer was used [13]. It is noted that the velocity distributions shown in Fig.…”

Section: The Collisional-radiative Modelmentioning

confidence: 99%

A Collisional-Radiative Model for Hydrogen Atom Including Velocity Changing Collisions

Fujii

Shikama

Sawada

et al. 2011

Plasma and Fusion Research

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We develop a collisional-radiative model for calculating the velocity distributions of excited hydrogen atoms. In the model, the velocity distributions are approximated using linear combinations of several basis functions which are treated as discrete velocity states, and only charge exchange collisions with proton are considered as velocity changing collisions. The populations in the velocity and excited states are calculated under an assumption of a quasi-stationary state. With the model we derive the velocity distribution of the ground state atoms from that of excited atoms in the n = 3 level observed for an LHD plasma, where n is the principal quantum number. The mean kinetic energy of the ground state atoms is estimated to be 5.6 eV, which is 0.05 eV less than that of the n = 3 atoms.

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Development of multiwavelength-range fine-resolution spectrometer for hydrogen emissions and its application to large helical device periphery plasmas

Cited by 8 publications

References 11 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

A Collisional-Radiative Model for Hydrogen Atom Including Velocity Changing Collisions

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