Inverse-bremsstrahlung absorption of an intense laser field in cluster plasma

Inverse-bremsstrahlung absorption of an intense laser field in cluster plasma is considered in the Born approximation with allowance made for electron interaction with the entire subsystem of clustered ions. The electromagnetic power absorbed in plasma is calculated for linearly and circularly polarized laser radiations. It is shown that plasma “clustering” can give rise to much more effective absorption of electromagnetic energy as a result of collisions. The collective effects (the action of the overall field of clustered ions on an electron) dominate over the elementary processes (electron scattering by individual ions in the cluster) in the course of inverse bremsstrahlung.     

Coherent acceleration by laser pulse echelons in periodic plasma structures

We consider a possibilty to use an echelon of mutually coherent laser pulses generated by the emerging CAN (Coherent Amplification Network) technology for direct particle acceleration in periodic plasma structures. We discuss resonant and free streaming configurations. The resonant plasma structures can trap energy of longer laser pulses but are limited to moderate laser intensities of about 10¹⁴?W/cm² and are very sensitive to the structure quality. The free streaming configurations can survive laser intensities above 10¹⁸?W/cm² for several tens of femtoseconds so that sustained accelerating rates well above TeV/m are feasible. In our full electromagnetic relativistic particle-in-cell (PIC) simulations we show a test electron bunch gaining up to 200?GeV over a distance of 10.2?cm only.     

Radiative losses in plasma accelerators

We investigate the dynamics of a relativistic electron in a strongly nonlinear plasma wave in terms of classical mechanics by taking into account the action of the radiative reaction force. The two limiting cases are considered. In the first case where the energy of the accelerated electrons is low, the electron makes many betatron oscillations during the acceleration. In the second case where the energy of the accelerated electrons is high, the betatron oscillation period is longer than the electron residence time in the accelerating phase. We show that the force of radiative friction can severely limit the rate of electron acceleration in a plasma accelerator.     

Photoinduced electron transfer from electron donor to bis-carbocyanine dye in excited triplet state

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Calculation of the thermodynamic potentials of changes in translational, rotational, and vibrational degrees of freedom in the dimerization of aromatic molecules

The work presents a method for calculating the thermodynamic potentials (free Gibbs energy, enthalpy, and entropy) and an analysis of the contributions of changes in translational, rotational, and vibrational degrees of freedom to the energy characteristics of the dimerization of aromatic compounds. On the whole, changes in the Gibbs energy caused by these contributions were shown to exceed the experimental energies of dimerization in solution in magnitude, which was evidence of the necessity of taking them into account for the aggregation of molecules. We determined changes in the Gibbs energy and entropy of translational, rotational, and vibrational (mechanical) degrees of freedom and the enthalpy of vibrations, which can be used to analyze the energy characteristics of dimerization reactions. These dimerization energy components should be calculated separately for each compound.     

Modeling of quartz dielectric spectrum in the region of establishing electron polarization processes

We discuss the practical efficiency of simulation of a real frequency characteristic of complex permeability of quartz α-SiO₂ crystals in the frequency range corresponding to establishment of elastic electron polarization. In the calculations, use was made of various formulas for permittivity as well as classical and quantummechanical models of ion shell configuration. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 32–38, November, 2008.     

Transformation of a nonlinear plasma wave into electromagnetic radiation in a periodic magnetic field

We study transformation of a nonlinear plasma wave into electromagnetic radiation in the periodic static magnetic field of an undulator. Such a wave can be excited by a short laser pulse or a relativistic electron bunch. The features of relativistic upper-hybrid plasma oscillations are analyzed. In the approximation of constant pump, resonance conditions of excitation of an electromagnetic wave and the characteristic transformation length are found. The nonlinear stage of transformation with allowance for pump depletion is considered. The studied phenomenon can be used for development of a high-power terahertz-radiatoin source. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 6, pp. 496–507, June 2007.