Elastic and Excitation Electron Collisions with Atoms

Trajmar, S.; Kanik, I.

doi:10.1007/978-1-4757-9319-2_3

Cited by 10 publications

(9 citation statements)

References 132 publications

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“…3. The filled circles are the recommended values of Trajmar and Kanik (1995) for excitation of the 2p state. These values were obtained from a critical review of all the existing experimental data for integrated cross sections.…”

Section: (4b) Integrated Cross Sectionsmentioning

confidence: 99%

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Principal Quantum Number Dependence for ElectronHydrogen Collisions

Bubelev¹,

Madison²,

Stelbovics³

et al. 1996

Aust. J. Phys.

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Over the last two decades, there has been considerable interest in the electron-atom scattering problem. Most of this work has concentrated on elastic scattering and excitation of the lowest energy states. However, due to recent technological advances, it is now becoming possible to examine experimentally the excitation of higher lying states. The important question then concerns whether these higher states contain new information. It has been argued that the scattering amplitudes for electron-helium excitation should scale with principal quantum and thus contain no new information. The purpose of this work is to examine the n-dependence for electron-hydrogen scattering. The converged-close-coupling and second-order distorted-wave methods have been used to calculate scattering amplitudes for excitation of the n = 2, 3 and 4 levels of the hydrogen atom. The n-dependence of the integrated cross sections, differential cross sections and angular correlation parameters will be discussed for energies from threshold to 500 eV.

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Section: (4b) Integrated Cross Sectionsmentioning

confidence: 99%

“…Recently there has been considerable interest in integrated cross sections (IeS) for electron scattering from hydrogen (Trajmar and Kanik 1995). Experiments are currently in progress at JPL to measure the polarisation fractions and integrated cross sections for exciting the 2p, 3p and 4p levels of hydrogen (Slevin 1994).…”

Section: (4b) Integrated Cross Sectionsmentioning

confidence: 99%

Principal Quantum Number Dependence for ElectronHydrogen Collisions

Bubelev¹,

Madison²,

Stelbovics³

et al. 1996

Aust. J. Phys.

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“…9) The experimental parameters for hydrogen plasma are T e ¼ 2 eV, T i ¼ 0:3 eV, n e ¼ 2 Â 10 12 cm À3 , P ¼ 3:0 mTorr, r ¼ 2:5 cm, and B ¼ 500 G, where P is the filling pressure of the hydrogen gas, and r is half of the interval between the magnets. For these parameters, the loss width of the electron energy is calculated as d T ¼ 0:16 cm, where n n ¼ 8:3 Â 10 12 cm À3 and L ¼ 7:85 cm are used from the values of P and r, and as for en in en , experimental and theoretical cross sections for electron collision with hydrogen 14) is used. On the other hand, in their experiment, the loss width of the plasma energy changes from d T ¼ 0:16 to 0.6 cm according to the probe position from the wall.…”

Section: Comparison Of D T With Experimental Resultsmentioning

confidence: 99%

“…where n n is the density of the neutral particle and en is the electron-neutral particle collision cross section. Because the dependence of en on the electron energy is small for the parameters of the negative ion source, 14) we assumed that en is independent of the electron energy in deriving g T e . In Fig.…”

Section: Analysis Of Loss Width Of Electron Energymentioning

confidence: 99%

Estimation of Width of Electron Energy Loss Region in Cusp Magnetic Field in Negative Ion Sources

Fukano

Hatayama

Ogasawara

2007

jjap

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The loss width of electron energy in the cusp magnetic field in negative ion sources is investigated analytically. Energy equation and continuity equation for electrons are solved with heat flux and particle flux parallel and perpendicular to the magnetic field. Electron energy and density perpendicular to the magnetic field are assumed to decrease exponentially with each decay length and the cusp loss width is defined by the doubling of the decay length. An expression of the ratio of the cusp loss width of electron energy to that of electron density is obtained. The ratio of the cusp loss width depends on electron collision frequencies across the magnetic field and a heat transmission coefficient defined by the ratio of the heat flux to the particle flux multiplied by the electron temperature along the magnetic field. The heat transmission coefficient is related to the sheath potential on the wall surface. Both parameter dependence and the calculated value of the cusp loss width of electron energy derived from our analysis are in good agreement with Horiike et al.'s experimental result for the magnetic multipole ion source.

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“…Laboratory measurements of the e-H momentum transfer cross sections have been performed by Williams (1975a,b); Callaway & Williams (1975); Shyn & Cho (1989); Shyn & Grafe (1992) (for a detailed review of the experimental methods and results, see Bederson & Kieffer 1971;Trajmar & Kanik 1995). Theoretical and experimental results are shown in Fig.…”

Section: E -Hmentioning

confidence: 99%

Three-fluid plasmas in star formation

Pinto

Galli

2008

A&A

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Context. The charged component of the insterstellar medium consists of atomic and molecular ions, electrons, and charged dust grains, coupled to the local Galactic magnetic field. Collisions between neutral particles (mostly atomic or molecular hydrogen) and charged species, and between the charged species themselves, affect the magnetohydrodynamical behaviour of the medium and the dissipation of electric currents. Aims. The friction force due to elastic collisions between particles of different species in the multi-component interstellar plasma is a nonlinear function of the temperature of each species and the Mach number of the relative drift velocity. The aim of this paper is to provide an accurate and, as far as possible, complete set of momentum transfer rate coefficients for magnetohydrodynamical studies of the interstellar medium. Methods. Momentum transfer rates are derived from available experimental data and theoretical calculations of cross sections within the classic approach developed by Boltzmann and Langevin for a wide range of values of the temperature and the drift velocity. Results. Accurate numerical values for momentum transfer rates are obtained and fitted to simple analytical formulae expressing the dependence of the results on the gas temperature and the relative drift velocity. The often used polarization approximation is in satisfactory agreement with our results only for collisions between H 2 and molecular ions (HCO + , H + 3 ). For other kinds of collisions, the polarization approximation fails by large factors, and must be replaced by more accurate expressions.

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Elastic and Excitation Electron Collisions with Atoms

Cited by 10 publications

References 132 publications

Principal Quantum Number Dependence for ElectronHydrogen Collisions

Principal Quantum Number Dependence for ElectronHydrogen Collisions

Estimation of Width of Electron Energy Loss Region in Cusp Magnetic Field in Negative Ion Sources

Three-fluid plasmas in star formation

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Elastic and Excitation Electron Collisions with Atoms

Cited by 10 publications

References 132 publications

Principal Quantum Number Dependence for ElectronHydrogen Collisions

Principal Quantum Number Dependence for ElectronHydrogen Collisions

Estimation of Width of Electron Energy Loss Region in Cusp Magnetic Field in Negative Ion Sources

Three-fluid plasmas in star formation

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Principal Quantum Number Dependence for ElectronHydrogen Collisions

Principal Quantum Number Dependence for ElectronHydrogen Collisions