Estimate of the Negative-Ion Density in O<sub>2</sub>/Ar ECR Plasma Utilizing Ion Acoustic Waves

Shindo, Masako; Kawai, Yoshinobu

doi:10.1143/jpsj.70.621

Cited by 8 publications

(5 citation statements)

References 22 publications

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“…The oxygen molecule density is thus on par with the measured values. Shindo and Kawi [36] have measured the electronegativity in an electron cyclotron resonance (ECR) discharge using ion acoustic waves. They formed the discharge in a stainless steel chamber of diameter 29 cm and length 70 cm.…”

Section: Resultsmentioning

confidence: 99%

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Guðmundsson¹

2004

J. Phys. D: Appl. Phys.

104

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A global (volume averaged) model of oxygen discharges is used to study the transition from a recombination dominated discharge to a detachment dominated discharge. The model includes the metastable oxygen molecules O2(a 1Δg) and and the three Herzberg states . Dissociative attachment of the oxygen molecule in the ground state and the metastable oxygen molecule O2(a 1Δg) are the dominating channels for creation of the negative oxygen ion O−. At high pressures, dissociative attachment of the Herzberg states contributes significantly to the creation of the negative oxygen ion, O−. The detachment by a collision of the metastable oxygen molecule with the oxygen ion, O−, is a significant loss process for the O− at pressures above 10 mTorr. Its contribution to the loss is more significant at a lower applied power, but at the higher pressures it is always significant. Detachment by collision with O(3P) is also an important loss mechanism for O−. We find that ion–ion recombination is the dominating loss process for negative ions in oxygen discharges at low pressures and calculate the critical pressure where the contributions of recombination reactions and detachment reactions are equal. This critical pressure depends on the applied power, increases with applied power and is in the range 5–14 mTorr in the pressure and power range investigated.

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Section: Resultsmentioning

confidence: 99%

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Guðmundsson¹

2004

J. Phys. D: Appl. Phys.

104

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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%

“…The stainless steel chamber is 29 cm in diameter and 70 cm long. The solid line shows model calculation at 800 W and the dotted line at 2400 W. The electronegativity in electron cyclotron resonance discharge is measured by ion acoustic waves (IAW)[53] and Langmuir probes[54].…”

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confidence: 99%

Oxygen discharges diluted with argon: dissociation processes

Guðmundsson

Thorsteinsson

2007

Plasma Sources Sci. Technol.

260

185

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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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“…Plasmas containing a fraction of negative ions possess characteristic dynamical properties that may differ substantially from those of "traditional" (textbook) electronion plasmas. Such plasmas have been generated in the laboratory by using a Q-machine [7,8], a double plasma device [9][10][11], electron cyclotron resonance (ECR) based plasma devices [12,13] and specially designed discharge chambers [14]. Negative ion plasmas (NIP) have also been observed in Space environments, e.g.…”

Section: Introductionmentioning

confidence: 99%

Coexistence of negative and positive polarity electrostatic solitary waves in ultradense relativistic negative-ion-beam permeated plasmas

Elkamash

Kourakis

2018

Physics of Plasmas

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The criteria for occurrence and the dynamical features of electrostatic solitary waves in a homogeneous, unmagnetized ultradense plasma penetrated by a negative ion beam are investigated, relying on a quantum hydrodynamic model. The ionic components are modeled as inertial fluids, while the relativistic electrons obey Fermi-Dirac statistics. A new set of exact analytical conditions for localized solitary pulses to exist is obtained, in terms of plasma density. The algebraic analysis reveals that these depend sensitively on the negative ion beam characteristics, that is, the beam velocity and density. Particular attention is paid to the simultaneous occurrence of positive and negative potential pulses, identified by their respective distinct ambipolar electric field structure forms. It is shown that the coexistence of positive and negative potential pulses occurs in a certain interval of parameter values, where the ion beam inertia becomes significant.

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Estimate of the Negative-Ion Density in O₂/Ar ECR Plasma Utilizing Ion Acoustic Waves

Cited by 8 publications

References 22 publications

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Oxygen discharges diluted with argon: dissociation processes

Coexistence of negative and positive polarity electrostatic solitary waves in ultradense relativistic negative-ion-beam permeated plasmas

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Estimate of the Negative-Ion Density in O2/Ar ECR Plasma Utilizing Ion Acoustic Waves

Cited by 8 publications

References 22 publications

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

Oxygen discharges diluted with argon: dissociation processes

Coexistence of negative and positive polarity electrostatic solitary waves in ultradense relativistic negative-ion-beam permeated plasmas

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Product

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Estimate of the Negative-Ion Density in O₂/Ar ECR Plasma Utilizing Ion Acoustic Waves