Cross Sections for Electron Collisions with Hydrogen Molecules

Yoon, Jung‐Sik; Song, Mi‐Young; Han, Jin-Yi; Hwang, Sung Ha; Chang, Won‐Seok; Lee, BongJu; Itikawa, Yukikazu

doi:10.1063/1.2838023

Cited by 299 publications

(189 citation statements)

References 61 publications

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“…6. σ k were taken from Yoon et al 29 for electron collisions with H 2 , from Shah et al 30 for electron collisions with H, and from Wetzel et al 31 for electron collisions with Ar. Yoon et al 29 compiled a collection of recommended values of cross sections for electron collisions with hydrogen molecules. We consider these data as the presently most reliable data set.…”

Section: Electron Collisionsmentioning

confidence: 99%

Ion chemistry in H2-Ar low temperature plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

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A rate equation model is devised to study the ion composition of inductively coupled H 2 -Ar plasmas with different H 2 -Ar mixing ratios. The model is applied to calculate the ion densities n i , the wall loss probability of atomic hydrogen β H , and the electron temperature T e . The calculated n i 's of Ar + , H + , H + 2 , H + 3 and ArH + are compared with experimental results. Calculations were made for a total gas pressure of 1.0 Pa. The production and loss channels of all ions are presented and discussed in detail. With the production and loss rates the density dependence of each ion on the plasma parameters are explained. It is shown that the primary ions H + 2 and Ar + which are produced by ionization of the background gas by electron collisions are effectively converted into H + 3 and ArH + . The high density of ArH + and Ar + is attributed to the low loss to the walls compared to hydrogen ions. It is shown that the H + /H + 2 density ratio is strongly correlated to the H/H 2 density ratio. The dissociation degree is around 1.7 %. From matching the calculated to the measured atomic hydrogen density n H the wall loss probability of atomic hydrogen on stainless steel β H was determined to be β H = 0.24. The model results were compared with recently published experimental results. The calculated and experimentally obtained data are in fair agreement.

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Section: Electron Collisionsmentioning

confidence: 99%

Ion chemistry in H2-Ar low temperature plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

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“…The cross sections for collisions of H − with H 2 are reviewed in Appendix A. The electron attachment cross section is a fit to the high energy portion of the recommendation of Joon et al [27] and is usually negligible for the high mean energy electrons considered even when allowances are made for possible dissociative attachment to vibrationally excited H 2 molecules. The estimated H − production at surfaces is typical of the experimental results of [28,29,30].…”

Section: Kinetics Modelmentioning

confidence: 99%

Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H₂

Phelps

2011

Plasma Sources Sci. Technol.

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Abstract.A model of the collisional kinetics of energetic hydrogen atoms, molecules, and ions in pure H 2 discharges is used to predict H α emission profiles and spatial distributions of emission from the cathode regions of low-pressure, weakly-ionized discharges for comparison with a wide variety of experiments. Positive and negative ion energy distributions are also predicted. The model developed for spatially uniform electric fields and current densities less than 10 −3 A/m 2 is extended to non-uniform electric fields, current densities of 10 3 A/m 2 , and electric field to gas density ratios E/N = 1. , and H − ions, fast H atoms, and fast H 2 molecules, and with reflection, excitation, and attachment to fast H atoms at surfaces. The H α excitation and H − formation occur principally by collisions of fast H, fast H 2 , and H + with H 2 . Model simplifications include using a one-dimensional geometry, a multi-beam transport model, and the average cathode-fall electric field. The H α emission is linear with current density over eight orders of magnitude. The calculated ion energy distributions agree satisfactorily with experiment for H + 2 and H + 3 , but are only in qualitative agreement for H + and H − . The experiments successfully modelled range from short-gap, parallel-plane glow discharges to beamlike, electrostatic-confinement discharges.

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“…If there are no multipole magnets confining the plasma, the particle and heat fluxes are set equal to those at the Debye sheath edge, by assuming the Debye length small compared to the driver dimensions. In this way the boundary condition for the continuity equation is:n · (−D a ∇n) = n c s (10) 020014-3…”

Section: Basic Equationsmentioning

confidence: 99%

“…For a molecular hydrogen discharge, the reaction rates corresponding to the ionization and excitation processes are taken from [4] whereas the rates for elastic collisions are obtained by averaging the elastic cross section in [10] over a Maxwellian distribution function. A summary of the reaction rates is plotted in fig.…”

Section: Basic Equationsmentioning

confidence: 99%