Balmer-Line Anomalies in a Turbulent Plasma

Gallagher, Charles C.; Levine, Morton A.

doi:10.1103/physrevlett.30.897

Cited by 16 publications

(5 citation statements)

References 7 publications

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“…As a consequence, depressions or 'dips' will appear on the spectrum. These complex phenomena are described by several authors [51][52][53][54][55][56][57][58][59]. The addition of these effects, typical in non-ideal plasma, results in multiple modifications in the H α profile, as observed in our measurements.…”

Section: Non-ideality Of the Edm Plasmasupporting

confidence: 74%

Time- and spatially-resolved characterization of electrical discharge machining plasma

Descoeudres

Hollenstein

Wälder³

et al. 2008

Plasma Sources Sci. Technol.

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Plasma created during electrical discharge machining (EDM) is investigated with fast imaging and with time-and spatially-resolved optical emission spectroscopy. After the breakdown, the plasma develops very fast (< 50ns) and then remains stable. The plasma excites a broad volume around the electrode gap. Typical spectra show a strong H α and continuum radiation, with many lines emitted by impurities coming from electrodes materials. The plasma contamination from the electrodes is mostly concentrated in their vicinity. The electron density reaches 2·10 18 cm -3 at the beginning of the discharge. This extreme density causes merging of lines, strong Stark broadening and shift of the H α line. The density decreases afterwards rapidly with time. The electron temperature remains roughly constant around 0.7eV. The low temperature, the high density measured and other spectroscopic evidences prove that the EDM plasma is non-ideal (Γ ≅ 0.45).

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Section: Non-ideality Of the Edm Plasmasupporting

confidence: 74%

Time- and spatially-resolved characterization of electrical discharge machining plasma

Descoeudres

Hollenstein

Wälder³

et al. 2008

Plasma Sources Sci. Technol.

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“…Cohn et al 5 , showed for Lya that resonant effects between high and low frequency fields can influence the intensity profile dramatically. This effect was found experimentally by Gallagher and Levine 6 and by Rutgers and DeKluiver 7 for the Balmer lines.…”

Section: Introductionsupporting

confidence: 48%

Calculations and Measurements of the Dynamic Stark Effect in Hydrogen

Rutgers

Kalfsbeek

1975

Zeitschrift Für Naturforschung A

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A theory is given for the spectral profile of the first hydrogen Balmer line when the radiating neutral atom is under influence of both (quasi-) static and harmonically oscillating electric fields. Profiles, measured in a turbulent heating experiment, show a series of intensity maxima on the wings of the Balmer lines. If we assume a model for the spatial distribution of turbulent wave vectors, we can derive the fieldstrength and the direction of low-frequency (ion-acoustic) oscillations and the strength and frequency of high-frequency (Langmuir) oscillations.

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“…Finally, if resonant interactions between the Stark separation and the oscillations of the dynamic field occur, depressions or 'dips' appear on the spectrum. These complex phenomena are described by several authors [39][40][41][42][43][44][45][46][47]. The addition of these effects, typical in non-ideal plasmas, results in multiple modifications in the H α profile, as seen in figure 12.…”

Section: Non-ideality Of the Plasmamentioning

confidence: 95%

Optical emission spectroscopy of electrical discharge machining plasma

Descoeudres¹,

Hollenstein²,

Demellayer³

et al. 2004

J. Phys. D: Appl. Phys.

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Plasma created during electrical discharge machining is systematically investigated using optical emission spectroscopy. Typical spectra show a strong Hα and continuum radiation, with many lines emitted by impurities coming from electrode and workpiece materials. The dielectric molecules are cracked by the discharge. Changing polarity affects the electrode wear and workpiece erosion rates, which can be qualitatively seen on the spectra. Time-resolved spectroscopy shows that the plasma density reaches 2 × 1018 cm−3 at the beginning of the discharge. This extreme density causes the merging of lines, strong Stark broadening and shift of the Hα line. Afterwards, the density decreases rapidly with time. The electron temperature remains roughly constant around 0.7 eV. The low temperature and the high density measured prove that the EDM plasma is non-ideal (Γ ≃ 0.45). Absence of the Hβ line, asymmetric shape of the Hα line and complex structures around Hα are other spectroscopic evidences of the plasma non-ideality.

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Balmer-Line Anomalies in a Turbulent Plasma

Cited by 16 publications

References 7 publications

Time- and spatially-resolved characterization of electrical discharge machining plasma

Time- and spatially-resolved characterization of electrical discharge machining plasma

Calculations and Measurements of the Dynamic Stark Effect in Hydrogen

Optical emission spectroscopy of electrical discharge machining plasma

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