Absolute time-resolved x-ray laser gain measurement

We present the first direct measurement of the time evolution of the gain of a soft x-ray laser amplifier. The measurement is based on the injection of a seed pulse, obtained by high-order harmonic generation, into an x-ray laser medium. Strong amplification occurs when the seed pulse is synchronized with the gain period. By precisely varying the delay between the x-ray laser plasma creation and the seed pulse injection, the actual temporal evolution of the soft x-ray amplifier gain is obtained with a subpicosecond resolution.     

Two dimensional counterpropagating spatial solitons in photorefractive crystals

We demonstrate experimentally the existence of two transverse-dimensional counterpropagating (CP) incoherent spatial solitons in a 5 x 5 x 23 mm SBN:60Ce photorefractive crystal and investigate their dynamical behavior. We carry out numerical simulations that confirm our experimental findings. Substantially different behavior from the copropagating incoherent solitons is found. A symmetry breaking transition from stable overlapping CP solitons to unstable transversely displaced CP solitons is observed. We perform linear stability analysis that predicts the threshold for the split-up transition, in qualitative agreement with numerical simulations and experimental results.     

Nonlinear dynamics of transport barrier relaxations in tokamak edge plasmas

A new mechanism for intermittent relaxations of transport barriers is found by using three dimensional fluid turbulence simulations. This mechanism is generic since it only requires a stationary E x B shear flow. It is found here that if the flow shear increases faster than linearly with heating power, the relaxation frequency decreases with power. An analytical study reveals that this nonlinear dynamics is governed by a time delay for effective velocity shear stabilization.     

Chelate von β-Dicarbonylverbindungen und ihren Derivaten. XVII. Zur Kristallstruktur von Bis-(thioisobutyrylacetonato)-nickel(II)

The x-ray structure analysis of the title Ni^II compound being of the planar coordination type Ni[S₂O₂] gives Ni? S distances of 2.15 Å and Ni? O distances of 1.87 Å. The sulfur atoms are arranged in cis-position. In the chelate ring the C? C distance is shortened in sulfur neighbourhood. This indicates a fixation of the C?C double bonds in the complex.     

Mössbauer study of the kinetics of simulated corrosion process of iron in chlorinated aqueous solution around room temperature: The hyperfine structure of ferrous hydroxides and Green Rust I

The hyperfine structure of the two ferrous hydroxides, Fe(OH)₂, [2Fe(OH)₂, FeOCl] and Green Rust I obtained during the oxidation of iron in chlorinated aqueous medium is determined. The structure of GRI is proposed. The kinetics of oxidation and the role of the chlorine concentration is thoroughly discussed.     

Time-dependent correlations for a one-component plasma in a uniform magnetic field

We derive various sum rules for the time-displaced structure function of a classical one-component plasma subjected to an external uniform magnetic field. When the plasma has some translational invariance (i.e., homogeneous or translation-invariant along the field), we find that there are long-wavelength oscillations with well-defined frequencies. The results are obtained from linear response and macroscopic electrodynamics, as well as from the microscopic equations of motion (BBGKY hierarchy). In the presence of the magnetic field, the time-displaced structure function has a polynomial decay at large distances, even in the homogeneous case. When the plasma has no translational invariance, examples show a more complicated temporal behaviour in the long-length-scale limit, involving a superposition of oscillations over a continuous range of frequencies.