On the theory of scattering in media having space-time fluctuations

The propagation of electromagnetic waves in nondispersive media having space-time fluctuations of the permittivity is considered. Within the framework of the method of small perturbations the effective permittivity tensor and the spectrum of the scattered field are calculated. It is shown that the presence of time fluctuations affects the energy relationships for the propagating wave. In particular, for fairly fast fluctuations the average field of the wave increases regardless of scattering.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 2, pp. 249–256, February, 1972.The authors thank N. G. Denisov, N. S. Stepanov, Yu. A. Ryzhov, and V. V. Tamoikin for their helpful discussions.     

Intersubband cyclotron resonance of holes in strained Ge/GeSi(111) heterostructures with germanium wide quantum wells and cyclotron resonance of 1<Emphasis Type="Italic">L</Emphasis> electrons in GeSi layers

The submillimeter (?ω=0.5–5 meV) magnetoabsorption spectra of strained Ge/Ge_1?xSi_x(111) multilayer heterostructures with thick Ge layers (d_Ge=300–850 Å, d_GeSi≈200 Å, x≈0.1) are investigated at T=4.2 K upon band-gap optical excitation. It is revealed that the absorption spectra contain cyclotron resonance lines of 1L electrons localized in GeSi solid solution layers (unlike the previously studied structures with thin Ge layers as quantum wells for 3L electrons). The absorption spectra of the samples with thick Ge layers (d_Ge=800–850 Å) exhibit cyclotron resonance lines of holes due to transitions from the lower Landau levels in the first quantum-well subband to the Landau levels belonging to the third and fifth higher subbands.     

Anomalous Electric Fields Inside a Dense Plasma of a Current Sheet

For the first time there have been analyzed profiles of electric-field-sensitive n_a spectral lines of the Li-like impurity ions CIV, NV, OVI emitted by a hot dense plasma of a plane current sheet. Theoretical profiles of these lines have been calculated with an allowance for Anomalous Electric Fields (AEF). By comparing the experimental and theoretical profiles of the lines it has been established for the first time that in the plane current sheet there were developed AEF of rms strengths F₀ ≈ (100–120) kV/cm in the time interval from τ = ?0.2 μs to τ = 0 (the time τ was counted from the instant of the maximum intensity of the spectral line OVI 5291 Å). These results have been backed up by a similar analysis of the experimental profiles of the spectral line HeII 4686 Å of the primary gas of the discharge. The AEF reached these strengths at the same instant of time, τ = ?0.2 μs, when electron and ion temperatures reached their maxima: T_e ? 100 eV, T_i ≈ 300 eV. The instant τ = ?0.2 μs corresponds to a transition from the metastable stage to the explosive phase of the current sheet evolution. At this time the ratio of the AEF energy density to the thermal energy density of the plasma was § ≡ F²₀/[8π/N_eT_e + N_iT_i)] ≈ 10^?3, which exceeded a similar ratio for the thermal wave field by three orders of magnitude.