Medium-energy ion scattering by solid surfaces part II

Машкова, Е. С.; Molchanov, V. A.

doi:10.1080/00337577408244188

Cited by 73 publications

(5 citation statements)

References 46 publications

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“…The broad subject of particle-surface interactions from the point of view of fusion research has been thoroughly reviewed recently [90], particularly with regard to the existing database (see also some earlier reviews [91][92][93]). In the discussion here, we restrict ourselves to interactions of low energy (<500 eV) plasma edge particles with the material boundaries affecting primarily the impurity content of the edge plasma and the hydrogen recycling.…”

Section: Particle-surface Interactionsmentioning

confidence: 99%

Atomic and molecular database for fusion plasma edge studies

1989

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Section: Particle-surface Interactionsmentioning

confidence: 99%

Atomic and molecular database for fusion plasma edge studies

1989

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“…The stimulated emission of radiation in a transverse magnetic field has been analyzed by Dreicer, 3 Pantell, Soncini, and Puthoff, 4 Madey and co-workers, 5 * 6 and Sukhatme and Wolff. 7 All of these theories are quantum mechanical in nature. They give the impression that they have to be so, since it is argued that it is the electron recoil Ap =h/\ c , where X c is the Compton wavelength, which is the source of a finite gain.…”

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confidence: 99%

Orientation of Atoms by Collisions with Inclined Surfaces

et al. 1976

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We have measured large orientations for Ar n states excited by 300-keV Ar + impact on solid Cu surfaces at grazing incidence. We report circulary polarized light fractions of up to 76% and interpret the excitation mechanism as an orbital-angular-momentum effect. As an application of this new excitation scheme, a zero-field level-crossing experiment is presented.We report new experiments which confirm and extend the recent observation that the excitation of fast ion beams by impact with inclined solid amorphous surfaces can lead to appreciable excited-state orientations. 1 We present measurements of angular distributions of the scattered ion current which support the assumption that near grazing incidence, there is a well-defined direction for the outgoing oriented atoms, as in "tilted-foil" experiments. 2 We also give the first results for the application of this "tilted-surface" effect to atomic level-crossing studies.The experimental setup is shown in Fig. 1. With the axes indicated, the direction of observation was along Ox. The incident beam direction is along Oz, the target surface normal makes an angle a with the -y axis in the yz plane, and we anticipate the results given below by ascribing an angle 9 to the average forward-scattered particle direction. The target was amorphous Cu, of dimensions 30 mmxl5 mmxl mm, and its surface to spectrometer FIG. 1. Experimental setup. The beam cross section is 0.5x 5 mm 2 " was mechanically polished flat to 2 jum. It was mounted on a shaft which was along Ox, and the angle a could be set to a precision of ± 0.17°. A 1-mm-diam pickup wire was mounted parallel to and off center from the x axis in such a way as to describe a circle of radius 7 cm about that axis. The scattered beam current could be measured with this wire as a function of y, in 1.4° steps. The pickup wire and the target could be held independently at variable potentials to suppress secondary-electron emission.The optical system consisted of an achromatic A/4 plate and a linear polarizer, followed by a single imaging lens, a 0.3-m grating spectrometer, and a photo multiplier tube in photon-counting mode. The viewing region was approximately 7 mm in diameter in the yz plane, and was centered on the x axis. Spectra were built up by repetitive sweeping of the wavelength proportional to collected charge of the unbiased target (our results are independent of secondary-electron emission) and recording the photon counts in a synchronized multichannel scaler. Similarly level-crossing curves were obtained by sweeping the magnetic flux B z , proportional to time at less than ± 5% beam fluctuations and recording photons of a particular line and polarization. B z , was applied by Helmholtz coils aligned along the scattered beam direction Oz'.In order to determine excited-state orientations of free scattered ions we measured the normalized Stokes parameter S/I= {la" -Io + )/(Ia" + Ia + ) by rotation of the A/4 plate in steps of 90°, where Jcr" and Ia + are, respectively, right and left circularly polarized light inte...

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“…Based on the physics of charged particle channeling in crystals, the interaction of an incident ion with a reflecting surface was described in the approximation of a continuous atomic potential of the surface. (We have to note that the term a surface channeling was introduced in the research on theoretical treatments of ion scattering by solid crystalline surfaces in [51], and successfully on an experimental proof of the phenomenon existence in [52]. However, these studies have examined the projectile motion into the bulk surface region of the crystal as channeling along length paths through the solid).…”

Section: Introductionmentioning

confidence: 99%

Surface Channeling of Charged and Neutral Beams in Capillary Guides

Dabagov

Dik

2022

QuBS

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In this review work, the passage of charged and neutral beams through dielectric capillary guides is described from a uniform point of view of beams channeling in capillaries. The motion of beams into the hollow channels formed by the inner walls of capillaries is mainly determined by multiple small-angle scattering (reflection) and can be described in the approximation of surface channeling. It is shown that the surface interaction potential in the case of micro- and nano-capillaries is actually conditioned by the curvature of the reflecting surface. After presenting the analysis of previously performed studies on X-rays propagation into capillaries, which is valid for thermal neutrons, too, the surface channeling formalism is also developed for charged particle beams, in particular, moving in curved cylindrical capillaries. Alternative theories explaining experimental results on the beams passage through capillaries are based on simple thermodynamic estimates, on various diffusion models, and on the results of direct numerical simulations as well. Our work is the first attempt to explain the effective guiding of a charged beam by a capillary from the general standpoint of quantum mechanics, which made it possible to analytically explore the interaction potential for surface channeling. It is established that, depending on the characteristics of a projectile and a dielectric forming the channel, the interaction potential can be either repulsive or attractive; the limiting values of the potential function for the corresponding cases are determined. It has been demonstrated that the surface channeling behaviour can help in explaining the efficient capillary guiding for radiations and beams.

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Medium-energy ion scattering by solid surfaces part II

Cited by 73 publications

References 46 publications

Atomic and molecular database for fusion plasma edge studies

Atomic and molecular database for fusion plasma edge studies

Orientation of Atoms by Collisions with Inclined Surfaces

Surface Channeling of Charged and Neutral Beams in Capillary Guides

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