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971.
972.
A. L. Goldenberg V. N. Manuilov M. Yu. Glyavin 《Radiophysics and Quantum Electronics》2005,48(6):461-465
We describe a nonadiabatic electron gun operated in the mode of a currentconfined by spatial charge and intended for producing
helical electron beams for high-power gyroresonantdevices.Results of numerical simulation of electron trajectories and electron-beam
parameters arepresented. It is shown that for a high operating current, the pitch factor and the electronvelocity spread can
be significantly better than in the conventional adiabatic systems.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48,No. 6, pp. 517–522, June 2005 相似文献
973.
974.
975.
V. Boutou M. A. Lebeault-Dorget A. R. Allouche C. Bordas J. Chevaleyre 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):448-453
In this article, we present results obtained on structures of small bare and oxygenated barium clusters produced by the laser vaporization technique. Contrary to the very weak Ba—Ba binding (0.202 eV), the Ba—O binding is rather strong (5.8 eV). As a consequence, extremely small amounts of oxygen in the cluster source are sufficient to induce the nucleation of oxygenated barium clusters. Surprisingly, at least for substoechiometric systems, BanOm clusters exhibit the same icosahedral structure as bare clusters do. Mass spectra seem to indicate that replacing a barium atom with a strongly polar BaO molecule does not affect the geometrical structure of the cluster. This aspect is more easily understandable if we assume that the oxygen atom takes place inside the structure of the Ban cluster without significant distortions. Ab-initio calculations have been undertaken in order to give a satisfactory account of this hypothesis. 相似文献
976.
Michael Fosmire Aurel Bulgac 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):458-461
We present findings from computer simulations of collisions of neon atomic beams with Na20 atomic clusters at different internal temperatures. A functional form for the double differential cross section is determined, and no simple signature of a phase transition is seen, even though the clusters undergo a melting phase transition in the temperature range investigated (100 K–400 K). However, such experiments can be used effectively to measure the internal cluster temperature. 相似文献
977.
We examine certain special features exhibited by various classes of linear operators acting in a hereditarily indecomposable
Banach space. For instance, we show that the family of all Riesz operators in a H.I. space forms a closed, 2-sided ideal.
We also give further characterizations of the class of scalar-type spectral operators (to those already given in [16]). The
final section discusses some properties of the spectral maximal spaces of (necessarily decomposable) linear operators in such
spaces.
Conferenza tenuta il 16 settembre 1997
The support of the German Academic Exchange Scheme (DAAD) is gratefully acknowledged 相似文献
978.
Y. A. Coutinho J. A. Martins Simões C. M. Porto 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):705-709
In this paper we investigate the effects of heavy Majorana neutrinos in the reaction e + e ? → W + W ?. We consider neutrino masses in the 1–10 TeV region. We show that at LEP II and NLC energies it is possible to use this processes to verify indirect evidence of heavy neutral particles with mixing angles of the order sin2 α = 0.01. We discuss the unitarity restrictions that can be obtained for vector singlet and fermion-mirror-fermion models. 相似文献
979.
L. Bugliaro J. Fröhlich G.M. Graf J. Stubbe C. Fefferman 《Communications in Mathematical Physics》1997,187(3):567-582
A Lieb-Thirring-Sobolev type inequality for Pauli Hamiltonians with magnetic fields is derived. The bound is in terms of an
effective field, whose energy is comparable to that of the magnetic field itself. An application to the stability of matter
in magnetic fields is given.
Received: 19 September 1996 / Accepted: 3 January 1997 相似文献
980.
This paper shows that the dimension of internal structure of a component can be measured remotely to a resolution better than 5 μm by use of the combination of high resolution optical microscopy and image processing.A specialised high resolution, long working distance and diffraction limited lens was used to image within the component. A series of digital images were made to map spatially the interior of the component. An edge detector was then used to localise the specific location of features in order that an accurate internal measurement could be made. A visualisation of the internal surface finish was also achieved. 相似文献