@inbook {2381,
title = {Pseudospectral Solution of the Boltzmann Equation: Quantum Cross Sections},
booktitle = {Rarefied Gas Dynamics},
series = {Aip Conference Proceedings},
volume = {1084},
year = {2009},
note = {ISI Document Delivery No.: BJF97Times Cited: 0Cited Reference Count: 18Chang, Yongbin Shizgal, Bernie D.Proceedings Paper26th International Symposium on Rarefied Gas Dynmaics (RGD26)JUN 20-JUL 25, 2008Kyoto, JAPANJapan Soc Promot Sci, Japan Aerpspace Explorat Agcy, Soc Promot Space Sci, Iwantani Naoji Fdn, Inoue Fdn Sci, Casio Sci Promot Fdn, Kaijma Fdn, IHI Corp, IHI Aerospac Engn Co Ltd, Osaka Vaccuun Ltd, Nissin Inc2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA},
pages = {421-426},
publisher = {Amer Inst Physics},
organization = {Amer Inst Physics},
address = {Melville},
abstract = {The relaxation of it nonequilibrium test particle population of mass m(1) in contact with a background gas of particles of mass m(2) at temperature T-b is studied with the spatially homogeneous Boltzmann equation. A pseudospectral method of solution is employed which is based on the discretization of the distribution function at a nonuniform grid that coincides with a quadrature. In order to implement this approach, the integral collision operator of the Boltzmann equation is expressed explicitly in terms of a kernel which is also discretized. This procedure fails if the classical differential collision cross section is used as it diverges for small scattering angles and the kernel is no longer well defined. In the present paper, we choose the interaction potential between the test particles and the background particles to be the Maxwell molecule interaction, that is, V (r) = V-o(d/r)(4) for which the eigenvalues and eigenfunctions are well known. We employ the quantum mechanical differential cross section for this potential, which is finite at zero scattering angle and we apply a pseudospectral approach based on speed polynomials. We compare the well known results for the eigenvalue spectrum of the Boltzmann collision operator for the classical differential cross section with the new results with the quantum differential cross section and the basis set defined by the speed polynomials. The relaxation to equilibrium of initial nonequilibrium distribution functions is studied with both methods.},
keywords = {Boltzmann equation, DISTRIBUTIONS, DYNAMICS, GASES, Maxwell molecules, pseudospectral method, quantum cross section, relaxation, VELOCITY DISTRIBUTION},
isbn = {0094-243X978-0-7354-0615-5},
url = {://000265564800068},
author = {Chang, Y. B. and Shizgal, B. D.},
editor = {Abe, T.}
}
@article {4644,
title = {Optimum phase angle for laser desorption ion trap mass spectrometry is dependent on the number of ions produced},
journal = {International Journal of Mass Spectrometry},
volume = {191},
year = {1999},
note = {ISI Document Delivery No.: 229EETimes Cited: 2Cited Reference Count: 22},
month = {Aug},
pages = {69-80},
type = {Article},
abstract = {Fur laser desorption sampling within a quadrupole ion trap, the phase and amplitude of the rf potential used to trap the ions, as well as the helium bath gas pressure, are important factors governing sensitivity. This article is concerned with investigating the dependence of trapping efficiency on the phase angle at the time that the laser fires. New data have been acquired demonstrating how the distribution of phase values that yield successful trapping, as well as the optimum phase for trapping, vary with the number of ions produced during the laser desorption event. It will also be shown that the position on the probe where the ions are created is a further factor in determining the optimum phase for trapping. Additional evidence taken from the laser desorption mass spectrometry literature will be used to propose a model for the dependence of the signal intensity versus phase relationship on the number of ions produced. It will be argued that trends in the data observed here are due to the effects of Debye shielding that accompany the desorption of substantial quantities of positive and negative ions. The dependency of the optimum phase angle on the position on the probe where the ions originate is not well understood at this time. Last, it will be shown how the pressure of helium within the trap does not influence the optimum phase value for trapping, but the effects of the bath gas pressure on trapping efficiency and fragmentation are interesting and will be discussed briefly. (Int J Mass Spectrom 190/191 (1999) 59-80) (C) 1999 Elsevier Science B.V.},
keywords = {DISTRIBUTIONS, ION TRAP, IONIZATION, laser desorption, trapping efficiency},
isbn = {1387-3806},
url = {://000082179900010},
author = {Robb, D. B. and Blades, M. W.}
}
@article {3813,
title = {Nonequilibrium effects in reactive systems; The effect of reaction products and the validity of the Chapman-Enskog method},
journal = {Physica a-Statistical Mechanics and Its Applications},
volume = {223},
number = {1-2},
year = {1996},
note = {ISI Document Delivery No.: TQ402Times Cited: 30Cited Reference Count: 62},
month = {Jan},
pages = {50-86},
type = {Article},
abstract = {The rates of gas phase reactions can be calculated from the averages of the appropriate reactive cross sections with the velocity distribution functions of the reacting species. The reactive process, especially for reactions with activation energy, removes translationally energetic species and the velocity distribution functions depart from Maxwellian. The rate coefficients can differ from the equilibrium rate calculated with the Maxwell-Boltzmann distribution. The extent of the departure of the distribution function from Maxwellian can be estimated from solutions of the Boltzmann equation with appropriate choices for the elastic and reactive collision cross sections. If there is a good separation in the elastic and reactive collision time scales, a steady solution of the Boltzmann equation can be obtained with a procedure analogous to the Chapman-Enskog method for transport coefficients. In the present paper, the nonequilibrium effects for model reactive systems of the type A + A reversible arrow B + B, with and without the reverse reaction, and the reaction A + C {\textendash}> products are examined with both a Chapman-Enskog method along with an explicitly time-dependent solution for the irreversible reaction A + A {\textendash}> B + B. The main objectives are to study the effect of the inclusion of the products with and without a reverse reaction as well as the range of validity of the Chapman-Enskog method.},
keywords = {ANOMALOUS TRANSPORT, DISTRIBUTIONS, EQUILIBRIUM, HEAT-FLUX, hydrodynamics, KINETIC-THEORY, LASER-INDUCED FLUORESCENCE, PERTURBATION, PLASMA, STRONGLY INHOMOGENEOUS SYSTEMS, VELOCITY},
isbn = {0378-4371},
url = {://A1996TQ40200005},
author = {Shizgal, B. D. and Napier, D. G.}
}