[en] Published in summary form only

[en] It is shown that at a consistent application of the WKB approximation the equation for the self-consistent plasma potential has no eigenfrequencies. (orig.)

[en] We calculate the frequency spectra of absolute optical instruments using the Wentzel–Kramers–Brillouin (WKB) approximation. The resulting eigenfrequencies approximate the actual values very accurately; in some cases they even give the exact values. Our calculations confirm the results obtained previously by a completely different method. In particular, the eigenfrequencies of absolute instruments form tight groups that are almost equidistantly spaced. We demonstrate our method and its results applied to several examples. (paper)

No abstract available

[en] Dechanneling, i.e. transition of particles from the aligned beam to the random beam, is caused mainly by two processes, scattering by nuclei and by electrons. In this paper it is considered the scattering of the channeled particle by lattice nuclei, which is relevant for many crystals and the dechanneling fraction in the planar case is calculated in the WKB approximation. The wave function of a planar channeled particle is written in the WKB formalism too. (author)

No abstract available

No abstract available

[en] We calculate the wave functions at origin of the 'equivalent' potential to the Leutwyler-Voloshin model and find that they reproduce the model results very well. 13 refs., 2 tabs. (Authors)

No abstract available

[en] In the uniform WKB(UWKB) theory, new better approximate solutions are investigated by adding a correction term. To assess the effect of the additional term, calcutions have been performed with four approximation methods. The improvement due to the correction term is found to be very significant in the range where the coupling constant is less than 1.2 a.u. In particular, the first peak in the inelastic differential cross section with the stationary phase method of UWKB modified Magnus approximation gives excellent agreement with the numerical 'exact' solution. (Author)