Particle generation in pulsed plasmas

Artelt, C.; Rott, M.; Höschen, T.; Behringer, K.; Bolt, H.

doi:10.1080/10519990701702628

Cited by 1 publication

(5 citation statements)

References 27 publications

(32 reference statements)

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“…The electron temperatures increase steeply at the beginning of each half-wave and drop more slowly after the current maximum. This may have the same reason as asymmetries in the ohmic power input, which are shown in [4]. The maximum temperatures are about 21000K and T e drops fairly slowly with current.…”

Section: Resultsmentioning

confidence: 80%

“…From a blue-shift of the Ar II lines -in addition their small Stark shift -a flow velocity could be derived, which was of the order of 20 km/s. For the plasmas in the vacuum tank a velocity of about 2 km/s had been measured in [4]. Figs.…”

Section: Resultsmentioning

confidence: 99%

“…Because of thermal expansion and interacting Lorentz forces the resulting plasmas were accelerated from the discharge chamber into the large expansion volume with high gas flow velocities, favoured by a Laval-type nozzle at the opening mouth of the discharge chamber. Details of the experiment have been described in [4], where plasma currents, arc voltages (of the order 100 V) and dissipated energies are also shown. Plasma parameters were derived from emission spectroscopy.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Windows in the discharge tank also allowed observation of the expanding plasma from the side; however, almost all results reported here were obtained end-on. For more information see [4].…”

Section: Experimental Set-upmentioning

confidence: 99%

“…been used for surface treatment [1] or for the deposition of thin films [2,3]. A recent paper [4] described the use of a pulsed arc at different currents and pressures for particle formation and growth processes, which are inherent to pulsed plasma devices. Carbon black was chosen here as a model substance because of its great industrial relevance.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle Generation

Behringer

Höschen

2008

Contrib. Plasma Phys.

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Pulsed arc plasmas were diagnosed by means of emission spectroscopy. A capacitor was discharged through argon and hydrogen leading to a few cycles of damped current oscillation with ≈120 µs period and 5-12 kA maximum current. Spectroscopic measurements in the visible range were carried out in order to characterise the electron temperature and density in the arc channel as well as electron and gas temperatures in the afterglow plasmas. Spectra were integrated over 10 µs time windows and shifted in time from pulse to pulse. The plasmas also contained substantial fractions of electrode material (brass), namely copper and zinc. The electron density was measured in the conventional way from the broadening of H ß or from the Ar I Stark width. In the arc channel, it ranged from about 3·1022 to 2·10 23 m −3 . The broadening of Zn II lines could also be used. Ratios of Ar I to Ar II and of Zn I to Zn II line intensities were analysed for the electron temperature. Line pairs were found which lay conveniently close in one frame of the spectrometer allowing automatic on-line analysis without relying on reproducibility. Atomic physics models including opacity were developed for Ar II and Zn II in order to check the existence of a Boltzmann distribution of their excited states. These calculations showed that the observed levels were in fact close to thermodynamic equilibrium, in particular, if the resonance lines were optically thick. Electron temperature measurements yielded values between 14000 K and 21000 K. The gas temperature in the afterglow, where particles should have formed, was derived from the rotational and vibrational temperatures of C2 molecular bands. Ratios between Cu I line intensities yielded the electron temperatures. Both were found to be a few 1000 K.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

“…Windows in the discharge tank also allowed observation of the expanding plasma from the side; however, almost all results reported here were obtained end-on. For more information see [4].…”

Section: Experimental Set-upmentioning

confidence: 99%