Search

We investigate the nonlinear radiative thermal conductivity model, which is theoretically well substantiated and based on a small number of assumptions. We consider the spatial and temporal evolutions for a low-density polymer foam heated by radiation waves taking into account the dependence of the absorption coefficients on the quantum energy. The form of the radiation wavefront (its slope and speed of propagation) differs from the classical form by a low-temperature “tongue” penetrating deep into the plasma. The plasma in this segment of the wavefront is heated up to a temperature of 1–2 eV by photons in the hard part of the spectrum, with energies for which hν/ kT > 4. We simulate numerically the experiments at the PHELIX facility to heat a low-density cellulose triacetate (TAC, C 12H 16O 8) taking into account the radiation transfer. The energy and the spectral flux of radiation that passed through the TAC layer are satisfactorily consistent with the experimental results. [ABSTRACT FROM AUTHOR]

A spectroradiometer operating in the 2-mm wavelength range for monitoring the ozonosphere from the Earth’s surface is described. Unique data on the vertical ozone distribution in layers of the stratosphere and mesosphere difficultly accessed by other techniques have been obtained with this instrument. The reliability of the results of measuring the vertical ozone distribution at millimeter waves is due to the high sensitivity of the spectroradiometer, its optimized characteristics, and highly efficient data-processing techniques. [ABSTRACT FROM AUTHOR]

The formation of craters in targets of various materials under the action of a high-power neodymium-laser pulse at radiation intensities from 10[sup 10] to 10[sup 14]W/cm[sup 2] was studied experimentally and theoretically. The interaction between the laser beam and solid targets is investigated to determine the efficiency of the ablation loading of various materials and the transformation of the laser energy into the energy of a shock wave. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

One-dimensional numerical calculations were performed to study the dependence of conditions for initiating thermonuclear combustion and of the target gain of direct-ignition inertial fusion targets ignited by a short radiation pulse on the initial temperature of a preliminarily compressed fuel and the initial heat energy distribution between plasma electrons and ions in the ignition region (igniter). The igniter parameters at which an effective thermonuclear target explosion with a G ∼ 10[SUP3] target gain occurred were shown to substantially depend on the initial temperature of the major fuel fraction and the initial heat energy distribution between igniter electrons and ions. The heat energy of the igniter passed a minimum as the size of the igniter decreased. The dependences of these minimum energies on the temperature of the major fuel fraction at various initial energy distributions between igniter electrons and ions were determined. An increase in the temperature of the major fuel fraction was shown to decrease the target gain. [ABSTRACT FROM AUTHOR]