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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Metal vapor target for precise studies of ion-atom collisions

Although different ion-atom collisions have been studied in various contexts, precise values of cross-sections for many atomic processes were seldom obtained. One of the main uncertainties originates from the value of target densities. In this paper, we describe a unique method to measure a target density precisely with a combination of physical vapor deposition and inductively coupled plasma optical emission spectrometry. This method is preliminarily applied to a charge transfer cross-section measurement in collisions between highly charged ions and magnesium vapor. The final relative uncertainty of the target density is less than 2.5%. This enables the precise studies of atomic processes in ion-atom collisions, even though in the trial test the deduction of precise capture cross-sections was limited by other systematic errors.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Influence of the renormalization plasma screening on the electron-atom collision in partially ionized plasmas

The renormalization plasma screening effects on the elastic electron-atom collision are investigated in partially ionized dense hydrogen plasmas using the eikonal method. It is found that the renormalization plasma screening suppresses the eikonal phase shift and cross section for the elastic electron-atom collision in partially ionized plasmas. It is also found that the renormalization plasma screening effect on the elastic electron-atom collision process increases with an increasing impact parameter. In addition, it is found that the maximum position of the differential cross section is receded from the center of the atom with an increase of the Debye length.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Renormalized dynamic charge shielding on the electron-atom collision: Eikonal analysis

The influence of the dynamic renormalization plasma shielding on the electron-atom collision is investigated in a dense strongly coupled electron system. The semiclassical eikonal method and effective interaction potential are employed to obtain the eikonal scattering phase shift and eikonal collision cross section as functions of the Debye length, impact parameter, projectile energy, and thermal energy. It is found that the renormalized dynamic charge shielding effect enhances the eikonal collision cross section. The variation of the dynamic renormalization shielding on the electron-atom collision is also discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1972

Use of the Glauber approximation in atomic collisions - A progress report.

Recent progress in the use of the Glauber (1970) theory for estimating atomic collision cross sections is reviewed. It appears that the Glauber approximation is reliable for electron-hydrogen elastic scattering and excitation at incident energies exceeding 30 eV. For more complicated atomic collisions, the usefulness of the Glauber approximation has not yet been significantly tested.

Gerjuoy, E.↗
NASA NTRS1974

Applications of the Glauber approximation to atomic collisions

Applications of the Glauber approximation to elastic and inelastic collisions of charged particles with neutral atoms are critically reviewed in an attempt to assess the utility of the Glauber approximation in the atomic collisions domain. Various alternative derivations of the Glauber amplitude formula, both for potential scattering and for composite collisions, also are described and compared. A number of possible problems for future research are listed.

Gerjuoy, E.↗
NASA NTRS2007

Convergent Close-Coupling Approach to Electron-Atom Collisions

It was with great pleasure and honour to accept the invitation to make a presentation at the symposium celebrating the life-long work of Aaron Temkin and Richard Drachman. The work of Aaron Temkin was particularly influential on our own during the development of the CCC method for electron-atom collisions. There are a number of key problems that need to be dealt with when developing a general computational approach to such collisions. Traditionally, the electron energy range was subdivided into the low, intermediate, and high energies. At the low energies only a finite number of channels are open and variational or close-coupling techniques could be used to obtain accurate results. At high energies an infinite number of discrete channels and the target continuum are open, but perturbative techniques are able to yield accurate results. However, at the intermediate energies perturbative techniques fail and computational approaches need to be found for treating the infinite number of open channels. In addition, there are also problems associated with the identical nature of electrons and the difficulty of implementing the boundary conditions for ionization processes. The beauty of the Temkin-Poet model of electron-hydrogen scattering is that it simplifies the full computational problem by neglecting any non-zero orbital angular momenta in the partial-wave expansion, without loosing the complexity associated with the above-mentioned problems. The unique nature of the problem allowed for accurate solution leading to benchmark results which could then be used to test the much more general approaches to electron-atom collision problems. The immense value of the Temkin-Poet model is readily summarised by the fact that the initial papers of Temkin and Poet have been collectively cited around 250 times to date and are still being cited in present times. Many of the citations came from our own work during the course of the development of the CCC method, which we now describe.

Bray, Igor↗