Measurements of negative ion density in O2/Ar electron cyclotron resonance plasma

We use a global (volume averaged) model to study the dissociation processes and the presence of negative ions and metastable species in a low pressure high density O 2 /Ar discharge in the pressure range 1-100 mTorr. The electron density and the fractional dissociation of the oxygen molecule increases with increased argon content in the discharge. We relate this increase in fractional dissociation to an increase in the reaction rate for electron impact dissociation of the oxygen molecule which is due to the increased electron temperature with increased argon content in the discharge. The electron temperature increases due to higher ionization potential of argon than for molecular and atomic oxygen. We find the contribution of dissociation by quenching of the argon metastable Ar m by molecular oxygen (Penning dissociation) to the creation of atomic oxygen to be negligible. The negative oxygen ion O − is found to be the dominant negative ion in the discharge. Dissociative attachment of the oxygen molecule in the ground state O 2 (X 3 − g ) and in particular the metastable oxygen molecule O 2 (a 1 g ) are the dominating channels for creation of the negative oxygen ion O − .

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“…(IAW) [53] and Langmuir probes [54]. They formed the discharge in a stainless steel chamber of diameter 29 cm and length 70 cm.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

Oxygen discharges diluted with argon: dissociation processes

Guðmundsson

Thorsteinsson

2007

Plasma Sources Sci. Technol.

260

185

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“…Methods determining negative-ion density in electronegative plasma from Langmuir probe measurements were proposed, e.g., in [1][2][3]. The approach in papers [2,3] is based on comparison of two probe characteristics, the first one taken in pure electropositive (Ar) plasma, the second one measured in electronegative (Ar/O 2 ) plasma.…”

Section: Introductionmentioning

confidence: 99%

“…The approach in papers [2,3] is based on comparison of two probe characteristics, the first one taken in pure electropositive (Ar) plasma, the second one measured in electronegative (Ar/O 2 ) plasma. We suggest here more general approach.…”

Section: Introductionmentioning

confidence: 99%

Study of Electronegative Ar/O² Discharge by Means of Langmuir Probe

Straňák

Blažek

Wrehde

et al. 2008

Contrib. Plasma Phys.

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The paper presents systematic Langmuir probe diagnostic of a dc discharge in Ar/O2 mixture with low fraction of O2, burning in a sputtering planar magnetron. Electron density, electron temperature and plasma potential are investigated in dependence upon experimental conditions like pressure, rate of oxygen, incoming power, and on balanced or unbalanced mode of magnetron. A new method of determining negative-ion density from the current-voltage characteristic is proposed. This method is based on comparison of the characteristic measured in electronegative plasma (e.g. Ar/O2) with a reference characteristic scanned in an electropositive counterpart (Ar), existing in similar conditions.

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“…Several diagnostic tools have been used by researchers to measure negative ion density in the electronegative plasmas. Some of the most commonly used diagnostic tools for measurement are laser photo-detachment, 14,15) ion acoustic wave, 16,17) mass spectroscopy 18) and electrostatic probes. [19][20][21] As Langmuir probes are the most widely used as well as reliable diagnostic tools for plasmas and also makes spatial measurement of plasma parameters possible therefore we have used a Langmuir probe in the experiment.…”

Section: Methodsmentioning

confidence: 99%

Study on negative ion production by electronegative gases in a helicon source

Chakraborty

Sharma

Neog

et al. 2020

Jpn. J. Appl. Phys.

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A helicon plasma source (HeliPS) experimental set-up is developed to perform experiments in electronegative gases. Characterization of HeliPS is done in argon and oxygen discharge by varying the working pressure, magnetic field strength as well as radio frequency power at 13.56 MHz thereby identifying the optimum parameters for its operation. After characterization, experiments have been performed in electronegative gases such as oxygen and hydrogen to understand the effect of electron affinity in producing negative ions in such plasmas. To enhance the negative ion production, both magnetic filter and magnetic cage, used innovatively in such a system, shows interesting results on their influence in electronegative plasma production.

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Measurements of negative ion density in O2/Ar electron cyclotron resonance plasma

Cited by 12 publications

References 21 publications

Oxygen discharges diluted with argon: dissociation processes

Oxygen discharges diluted with argon: dissociation processes

Study of Electronegative Ar/O² Discharge by Means of Langmuir Probe

Study on negative ion production by electronegative gases in a helicon source

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Measurements of negative ion density in O2/Ar electron cyclotron resonance plasma

Cited by 12 publications

References 21 publications

Oxygen discharges diluted with argon: dissociation processes

Oxygen discharges diluted with argon: dissociation processes

Study of Electronegative Ar/O2 Discharge by Means of Langmuir Probe

Study on negative ion production by electronegative gases in a helicon source

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Study of Electronegative Ar/O² Discharge by Means of Langmuir Probe