共查询到20条相似文献,搜索用时 864 毫秒
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Denisov A. P. Bryzgunov M. I. Ivanov A. V. Parkhomchuk V. V. Putmakov A. A. Reva V. B. 《Physics of Particles and Nuclei Letters》2019,16(6):876-884
Physics of Particles and Nuclei Letters - One way to increase the efficiency of electron cooling is to increase the electron density in the beam reference frame. As a rule, with an increase in the... 相似文献
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Leif Henriksen 《辐射效应与固体损伤》2013,168(1)
T. B. Rymer Methuen, London; Barnes and Noble, New York, 165 pages, 7 plates. £2.50 相似文献
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The arguments leading to the concept of an electron crystal in the low density regime of ‘jellium’ are reviewed. Ground-state properties discussed include estimates of the critical density at which the transition to a crystalline state takes place, and then in the low density regime the dielectric function, pair function and momentum distribution are dealt with. The magnetic character of the ground state as a function of density is also considered. The low-lying excitations of the Wigner electron crystal are phonon-like and hence the low temperature specific heat obeys a T 3 law. Defect models are considered in order to throw further light on the character of excited states. Finally experimental conditions favourable for electron crystallization are briefly considered. 相似文献
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Ballistic electron waveguides are open quantum systems that can be formed at very low temperatures at a GaAs/AlGaAs interface. Dissipation due to electron–phonon and electron–electron interactions in these systems is negligible. Although the electrons only interact with the walls of the waveguide, they can have a complicated spectrum including both positive energy bound states and quasibound states which appear as complex energy poles of the scattering S-matrix or energy Green's function. The quasibound states can give rise to zeros in the waveguide conductance as the energy of the electrons is varied. The width of the conduction zeros is determined by the lifetimes of the quasibound states. The complex energy spectrum associated with the quasibound states also governs the survival probability of electrons placed in the waveguide cavities. 相似文献
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The effect of trapped electron turbulence on the dynamics of a typical unstable mode is investigated. We establish that its principal effects are turbulence-induced additional collision frequencies for the trapped electrons and transit ions both of which are stabilizing. The resulting nonlinearly saturated fluctuation level is found to be considerably smaller than other estimates. The corresponding estimates of anomalous particle and thermal diffusion are also smaller than previous results. 相似文献
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Ch. Kleint 《Surface science》1988,200(2-3):472-489
Traced back to the early discoveries by Schottky and Johnson, a review will be given on the present state of electron emission noise phenomena and related fluctuations. Special emphasis is laid upon adsorbate induced noise under UHV conditions which can be investigated, at least in principle, down to single adparticle fluctuations. On the other hand, with increasing submonolayer coverage, adparticle interactions can play an important role which might even lead to collective phenomena. Different noise sources and models to describe them will be discussed. The examples for illustration are mainly taken from field emission investigations and will cover shot noise, prediffusion adparticle flip-flop, Brownian motion or concentration fluctuations in a patch, tunneling diffusion, trap and surface state governed emission noise and indications of phase transitions and soliton or domain wall movements. Some relations to current noise in solid state devices and to other noise sources and their characteristics will be mentioned. 相似文献
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《Superlattices and Microstructures》1998,23(1):121-137
The discovery of electron waveguiding in one-dimensional (1D) semiconductor nanostructures has uncovered a new regime of electron transport with fascinating physics. The device potential of electron waveguides, however, remains largely unexplored. Over the last few years, our interuniversity team has been conducting research on the physics, technology and opportunities for device applications of split-gate AlGaAs/GaAs electron waveguides. We have examined electronic devices based on electron transport, tunneling and interference. Many problems have been identified in transport-type devices, but much more research is required before the engineering potential of tunneling and interference devices is understood. We have also investigated the potential of electron waveguides in photonic applications, with emphasis on far-infrared (or THz) photodetectors. Our research to date has revealed strong photon-induced currents in antenna-coupled electron waveguides that arise from quantum thermopower. Far-infrared photodetectors based on photon-induced quantum transport remain an interesting opportunity for the application of electron waveguides. 相似文献
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The paper presents a study of the dependence of initiation and development of instability on the cyclotron frequency of electrons in a homogeneous plasma with cold ions and electrons forming two beams which move in the direction of, and opposite to, that of a constant magnetic field. It is demonstrated that for
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, and a brief comparison with the experimental results is carried out.The authors take this opportunity to thank Dr. M. Seidl for his valuable comments and stimulating discussions on this paper. 相似文献
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We present experimental conditions that lead to high-quality Cu2+-based double electron electron resonance (DEER) data. Such experiments are feasible at temperature of about 20 K, and sample
concentrations in the range of 0.15–1.5 mM. By systematically investigating the effects of pulse lengths, we find that observer
π pulse lengths of 20–48 ns provide reasonable modulation depths as well as signals. The length of the pump pulse needs to
be minimized (16 ns in our case). For a Cu2+–Cu2+ DEER measurement, the optimal frequency offset is about 100 MHz. For a Cu2+–nitroxide DEER measurement, the frequency offset is often varied in the range of 100–500 MHz, to probe orientational selectivity.
For both cases, the frequency of the pump pulse should be smaller than the observer pulse in order to obtain a larger modulation
depth. 相似文献
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采用法国的MAFIA程序计算电场.编制了TRAJ程序,用逐点跟踪计算电子轨迹,得到了束流包络.观察了在高压电场中栅压对束流光学传输的影响,并获得了在不同能量范围内的栅压聚焦作用,为栅压调节提供了理论依据,也为将来对其它规格的电子帘加速器的物理设计积累了十分宝贵的经验. 相似文献
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In this paper, we construct a parallel image of the conventional Maxwell theory by replacing the observer-time by the proper-time of the source. This formulation is mathematically, but not physically, equivalent to the conventional form. The change induces a new symmetry group which is distinct from, but closely related to the Lorentz group, and fixes the clock of the source for all observers. The new wave equation contains an additional term (dissipative), which arises instantaneously with acceleration. This shows that the origin of radiation reaction is not the action of a charge on itself but arises from inertial resistance to changes in motion. This dissipative term is equivalent to an effective mass so that classical radiation has both a massless and a massive part. Hence, at the local level the theory is one of particles and fields but there is no self-energy divergence (nor any of the other problems). We also show that, for any closed system of particles, there is a global inertial frame and unique (invariant) global proper-time (for each observer) from which to observe the system. This global clock is intrinsically related to the proper clocks of the individual particles and provides a unique definition of simultaneity for all events associated with the system. We suggest that this clock is the historical clock of Horwitz, Piron, and Fanchi. At this level, the theory is of the action-at-a-distance type and the absorption hypothesis of Wheeler and Feynman follows from global conservation of energy. 相似文献
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C. Manfredotti C. De Blasi S. Galassini G. Micocci L. Ruggiero A. Tepore 《Solid State Communications》1976,18(8):1063-1066
Measurements performed on n-GaS by means of the space-charge limited current method indicate the presence of a deep trap for electrons, at 0.57 eV from the conduction band and with a density of about 2.3 × 1013cm?3. Another deeper trap at 0.63 eV and with a density of 6 × 1012cm?3 is probably also present. The results seem to confirm the validity of a new direct method of analysis. Traps are tentatively attributed to compensated sulphur vacancies. 相似文献
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We here investigate the density and temperature dependence of polarization using the relativistic formalism for the electron–electron
interaction within the Fermi liquid model. The variational method has been used: the free energy has been minimized with respect
to the effective mass and the polarization parameter. Then we obtained the equation of state and magnetic susceptibility of
the system. The exact results for polarization and magnetic susceptibility have been obtained at zero temperature. It has
been shown that for a given temperature (density) there is a critical density (temperature) at which the ferromagnetic phase
can appear in an electron gas. The results are in agreement with previous work. Our results show that at nonzero temperatures
and in very low and very high densities the ferromagnetism phase cannot exist. 相似文献