Topic
Mean free path
About: Mean free path is a research topic. Over the lifetime, 4412 publications have been published within this topic receiving 114418 citations.
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TL;DR: In this article, the scattering from impurities in copper is analyzed in terms of s, p and d partial waves, and the anisotropic transition probability between points on the Fermi surface is calculated based on scattering phase shifts characterizing the impurity.
Abstract: The scattering from impurities in copper is analysed in terms of s, p and d partial waves. The (anisotropic) transition probability between points on the Fermi surface is calculated in terms of scattering phase shifts characterizing the impurity. Maps of the calculated scattering are presented for each phase shift and the corresponding Dingle temperatures are calculated for a variety of orbits seen in the de Haas-van Alphen effect. A procedure developed to calculate the impurity resistivity and anisotropy of the corresponding relaxation time demonstrated the need to use a vector mean free path in such a calculation. The calculated scattering is compared with experimental values in the Cu(Ni), Cu(Fe) and Cu(Al) systems and values derived for the scattering phase shifts.
49 citations
TL;DR: In this article, the effect of collisions on the ion-saturation current, the retarding field electron current, and the floating potential and the inferred electron temperature was investigated experimentally in a highly expanded low density flowing argon plasma using both single and double probes.
Abstract: : Experiments were performed in a highly expanded low density flowing argon plasma using both single and double probes. Results are obtained in the near free-molecule regime over a wide range of ratios of Debye length to probe radius, probe length to probe radius, and probe radius to relevant mean free path. The effect of collisions on the ion-saturation current, the retarding field electron current, the floating potential and the inferred electron temperature was investigated experimentally. An existing approximate analysis describing the collisional single probe ion-saturation current and the retarding field electron current was extended to describe the collisional double probe characteristic and magnitude of the single probe floating potential. (Author)
49 citations
TL;DR: In this article, a tube-like structure with a cross section of 25 nm × 25 nm has been created in a semiconductor and the mean free path of the electrons exceeds 10 μm -more than 400 times the confinement dimension.
49 citations
TL;DR: In this paper, a theoretical interpretation of the anomalous resistivity onset is proposed observing that (at long but finite mean free paths) nonresonant modes, associated with the effects of electronelectron collisions, are excited when the electron flow velocity along the magnetic field is roughly larger than the ion soundwave velocity.
Abstract: Experiments have shown the appearance of “nonclassical” resistivity, higher than that predicted by the known transport theory based on electron‐ion collisions, in magnetically confined plasmas where the electron gyrofrequency is larger than the Langmuir frequency and the electric field is well below the runaway threshold. A theoretical interpretation of the anomalous resistivity onset is proposed observing that (at long but finite mean free paths) nonresonant modes, associated with the effects of electron‐electron collisions, are excited when the electron flow velocity along the magnetic field is roughly larger than the ion sound‐wave velocity. The magnitude of anomalous resistivity is then discussed in relation with the nonlinear effects of resulting fluctuations and of related modes with wavelengths shorter than the mean free path. A comparison between several experiments on plasma confined in different stellarator and tokamak configurations is given. The differences in physical regimes that lead to various mechanisms for the appearance of “nonclassical” resistivity and the relationship with anomalous diffusion are pointed out.
48 citations
TL;DR: In this paper, the authors derived the mean free path for an electron or hole in any semiconductor obeys a simple universal law which implies a common phonon energy for electron and hole scattering and a dependence of mean free paths on threshold energy ( lambda varies as Ei-12/).
Abstract: Mean free paths associated with the scattering of electrons and holes are derived from experiments on impact ionisation in wide-gap semiconductors using the lucky-drift model. It is found that the mean free path for an electron or hole in any semiconductor obeys a simple universal law which implies a common phonon energy for electron and hole scattering and a dependence of mean free path on threshold energy ( lambda varies as Ei-12/). The latter dependence is plausible in terms of a simple view of scattering of high-energy carriers in a nonparabolic band. This universal model is derived on the basis of experimental data reported by various authors in Si, Ge, GaAs, and InP. Results for GaSb and its alloys appear to be anomalous, whereas data from GaInAs in InGaAsP tend to support the model. The model predicts the ratio of ionisation coefficients k= beta / alpha and its dependence on field and temperature. It is shown that k in any semiconductor is determined by only the ratio of threshold energies of electrons and holes. A comparison with reported values is made and brief discussions of the spin-orbit resonance effect in AlGaSb and of the enhancement in GaAs/AlGaAs multilayers are given.
48 citations