[en] The possibility of recurrence of the unique sporadic phenomenon - polar-cap absorption (PCA) - according to the full set of events for 1938-1986 is investigated. Repetition periods of PCA during 26-27 days and 32-33 days are detected by the method of time diagrams

[en] Analytical techniques have been utilized to obtain the radiation attenuation of nuclear power sources. This calculation was extended to cylindrical source geometry and results were computed by means of a computer program. The self-attenuation parameter of an annular fuel source is evaluated by analytical technique. The self-shielding parameter of a solid cylindrical source when the inner radius is allowed to approach zero is evaluated

No abstract available

No abstract available

[en] K emission line widths measured with a micrometer on integrated spectra of the Sun have a mean value of 38.2 km/s. A definition is proposed whereby the width is a measure in km/s at the e^-1 value of the difference between the intensity of the brighter K₂ peak over the K₁ background, reckoned from this latter level. Averaged spectra over different parts of the solar disc show the very appreciable contribution by rotation to the emission line width, making it imperative for any calibration of width with absolute magntiude to use a solar value derived from an integrated spectrum. Arguments are presented showing that the K emission profile observed in other stars is the profile of the typical bright mottle that should enable the derivation of chromospheric parameters. From measures of Doppler displacements of both K₂ and K₃ 'dark condensations' as seen on the Sun are at play in the atmospheres of stars with K emission. (author)

[en] The well-know anomalous absorption of transverse electromagnetic waves near the resonance point of a plasma surface is described as a phenomenon of radiative damping of waves. Reflection of a sharp plasma surface and from smoothly inhomogeneous plasma are considered separately. It is shown that during the reflection of E-waves from the surface of a smoothly bounded inhomogeneous plasma, radiative damping occurs in the reflecting point as a result of longitudinal plasma waves emission and it is also shown that anomalous absorption of electromagnet waves in the long-wavelength limit is significant as well as in the short wavelength

[en] We present mean energy measurements for the atom optics kicked rotor as the kicking period tends to zero. A narrow resonance is observed marked by quadratic energy growth, in parallel with a complete freezing of the energy absorption away from the resonance peak. Both phenomena are explained by classical means, taking proper account of the atoms' initial momentum distribution

No abstract available

[en] When an intense electromagnetic wave is incident obliquely on a sharply bounded overdense plasma, strong energy absorption can be accounted for by the electrons that are dragged into the vacuum and sent back into the plasma with velocities v≅v/sub osc/. This mechanism is more efficient than usual resonant absorption for v/sub osc//ω>L, with L being the density gradient length. In the very high-intensity CO₂-laser--target interaction, this mechanism may account for most of the energy absorption

[en] The paper is concerned with formation of a small-scale structure near the plasma resonance caused by an electromagnetic field penetrating into plasma. It is assumed that the electron density depends only on the square of electric field amplitude (E)². Also considered are condition when the field in the plasma is similar in structure to the field of an ordinary wave and in a linear approximation there is no interaction with an E-wave which in this case is in the resonance. It is shown, assuming that the external magnetic field is relatively small, that the small-scale structure is formed at (E)² > > Esub(cr)² (Esub(cr)² approximately νsub(e)/ω)). The electromagnetic field energy dissipation occurring therewith is of a universal nature and does not depend either on the value of νsub(e)/ω or on the particular type of the nonlinearity under consideration