Methods of Wall Charge Determination in External Electrode Gas Discharges. I. Experimental Arrangement

Kindel, E.; Arndt, R.

doi:10.1002/ctpp.19800200206

Cited by 7 publications

(3 citation statements)

References 15 publications

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“…An integral part of this analysis should be experimental tools to measure the charges accumulated in the wall. Some methods for this purpose already exist, using electric probes [4], optomechanical sensors [5], or the optopelectric Pockels effect [6]. We propose that measurement of the surface charges is also possible by infrared spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Infrared spectroscopy of surface charges in plasma-facing dielectrics

Rasek,

Bronold,

Fehske

2021

Preprint

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We propose to measure the surface charge accumulating at the interface between a plasma and a dielectric by infrared spectroscopy using the dielectric as a multi-internal reflection element. The surplus charge leads to an attenuation of the transmitted signal from which the magnitude of the charge can be inferred. Calculating the optical response perturbatively in first order from the Boltzmann equation for the electron-hole plasma inside the solid, we can show that in the parameter range of interest a classical Drude term results. Only the integrated surface charge enters, opening up thereby a very efficient analysis of measured data.

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Section: Introductionmentioning

confidence: 99%

Infrared spectroscopy of surface charges in plasma-facing dielectrics

Rasek,

Bronold,

Fehske

2021

Preprint

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“…There exists a number of techniques to estimate the charge accumulated by plasma-facing solids. Electric probes [9], surface potential measurements [10][11][12], opto-mechanical devices based on the reflection of a laser by a cantilever [13], and the Pockels effect of an electro-optic crystal [14][15][16][17][18][19] have been employed for that purpose. However, with the exception of the Pockels effect measurements, the methods are rather invasive.…”

Section: Introductionmentioning

confidence: 99%

Electron energy loss spectroscopy of wall charges in plasma-facing dielectrics

Thiessen

Bronold

Fehske

2019

Plasma Sources Sci. Technol.

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We propose a setup enabling electron energy loss spectroscopy to determine the density of the electrons accumulated by an electro-positive dielectric in contact with a plasma. It is based on a two-layer structure inserted into a recess of the wall. Consisting of a plasma-facing film made out of the dielectric of interest and a substrate layer the structure is designed to confine the plasmainduced surplus electrons to the region of the film. The charge fluctuations they give rise to can then be read out from the backside of the substrate by near specular electron reflection. To obtain in this scattering geometry a strong charge-sensitive reflection maximum due to the surplus electrons the film has to be most probably pre-n-doped and sufficiently thin with the mechanical stability maintained by the substrate. We demonstrate the feasibility of the proposal by calculating the loss spectrum for an Al2O3 film on top of a CaO layer. We find a reflection maximum strongly shifting with the density of the surplus electrons and suggest to use it for its diagnostics.

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“…So far only a few attempts have been made to measure the charge accumulated by a solid in contact with a plasma. Besides traditional electric probes [7] and micron-size opto-mechanical charge sensors [8], which both utilize the principle of electric influence, the optoelectric Pockels effect [9] has been used for that purpose. The latter was developed into a rather sophisticated tool for lateral imaging of the wall charge in barrier discharges [10].…”

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confidence: 99%

Measuring the plasma-wall charge by infrared spectroscopy

Rasek¹,

Bronold²,

Bauer³

et al. 2018

EPL

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We show that the charge accumulated by a dielectric plasma-facing solid can be measured by infrared spectroscopy. The approach utilizes a stack of materials supporting a surface plasmon resonance in the infrared. For frequencies near the Berreman resonance of the layer facing the plasma the reflectivity dip-measured from the back of the stack, not in contact with the plasmadepends strongly on the angle of incidence making it an ideal sensor for the changes of the layer's dielectric function due to the polarizability of the trapped surplus charges. The charge-induced shifts of the dip, both as a function of the angle and the frequency of the incident infrared light, are large enough to be measurable by attenuated total reflection setups.

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Methods of Wall Charge Determination in External Electrode Gas Discharges. I. Experimental Arrangement

Cited by 7 publications

References 15 publications

Infrared spectroscopy of surface charges in plasma-facing dielectrics

Infrared spectroscopy of surface charges in plasma-facing dielectrics

Electron energy loss spectroscopy of wall charges in plasma-facing dielectrics

Measuring the plasma-wall charge by infrared spectroscopy

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