Uniform susceptibility of classical antiferromagnets in one and two dimensions in a magnetic field

We simulated the field-dependent magnetization m(H,T) and the uniform susceptibility of classical Heisenberg antiferromagnets in the chain and square-lattice geometry using Monte Carlo methods. The results confirm the singular behavior of at small T,H: and , where D=3 is the number of spin components, J ₀=zJ, and z is the number of nearest neighbors. A good agreement is achieved in a wide range of temperatures T and magnetic fields H with the first-order 1/D expansion results (D.A. Garanin, J. Stat. Phys. 83, 907 (1996)). Received 20 March 2000     

Features of the Ignition of a Laser Fusion Target by a Converging Shock Wave

Journal of Experimental and Theoretical Physics - The compression and burning of a fusion target ignited by a focused shock wave produced at the action of a time-profiled second harmonic laser...     

Quasiclassical Hamiltonians for large-spin systems

We extend and apply a previously developed method for a semiclassical treatment of a system with large spin S. A multisite Heisenberg Hamiltonian is transformed into an effective classical Hamilton function which can be treated by standard methods for classical systems. Quantum effects enter in form of multispin interactions in the Hamilton function. The latter is written in the form of an expansion in powers of J/(TS), where J is the coupling constant. Main ingredients of our method are spin coherent states and cumulants. Rules and diagrams are derived for computing cumulants of groups of operators entering the Hamiltonian. The theory is illustrated by calculating the quantum corrections to the free energy of a Heisenberg chain which were previously computed by a Wigner-Kirkwood expansion. Received 5 May 1999 and received in final form 24 September 1999     

Indirect (x-ray) irradiation of encapsulated microtargets in the Iskra-5 facility

Experiments on the indirect (x-ray) irradiation of high-aspect-ratio capsules (with a diameter-to-thickness ratio ≈900) filled with DT gas are performed on the Iskra-5 laser facility. It is shown that all the characteristics measured (neutron yield, ion temperature, shell implosion time, etc.) are faithfully reproduced in calculations based on the one-dimensional SNDA (spectral nonequilibrium diffusion of absorption) program for nonequilibrium radiation gas dynamics. The calculations provide an explanation for the experimentally detected generation of a smaller number of neutrons in an experiment with a higher measured value for the ion temperature of DT gas. Zh. éksp. Teor. Fiz. 114, 1993–2003 (December 1998)     

Phase transitions in classical vector models

The equation of state obtained earlier /6/ for 3-dimensional Ising ferromagnets in the first order in$\text{1}\text{z}$ (z is the number of the nearest neighbours) is generalized with regard to the classical D-component vector model. The results obtained are valid in a wide temperature range |τ|?[z²(D+2)]^?1 (τ=(T_c-T)/T_c) and become exact in the limit D → ∞.     

Influence of the Asynchronous Multibeam Irradiation of a Spherical Fusion Target by Megajoule Laser Beams on the Efficiency of Thermonuclear Burning

We have studied the dependence of the compression and burning of a spherical direct-drive fusion target on the nonuniformity of its heating caused by the asynchronous arrival of laser beams under conditions of irradiation by a modern laser system with a total energy of 2 MJ intended for the fuel ignition and fusion energy evolution equal to the absorbed laser energy. The investigation is performed by numerical simulation based on 2D hydrodynamic codes. It is established that the limiting permissible spread of the moments of laser pulse action on the target for ignition significantly exceeds the level that can be ensured using modern methods of controlled temporal synchronization of laser beams.