Physical processes in a laser-greenhouse target: Experimental results, theoretical models, and numerical calculations.

Autor: Caruso, A., Demchenko, N., Demchenko, V., Garanin, S., Gavrilov, V., Gol'tsov, A., Gromov, A., Gus'kov, S., Kas'yanov, Yu., Kirillov, G., Kondrashov, V., Koval'skii, N., Lebo, I., Merkul'ev, Yu., Nikishin, V., Rozanov, V., Rupasov, A., Stepanov, R., Strangio, C., Sukharev, S.
Zdroj: Journal of Russian Laser Research; Jul2000, Vol. 21 Issue 4, p335-369, 35p
Abstrakt: The paper is devoted to recent results concerning investigation of physical processes occurring in a “laser greenhouse” target. Results of experimental and theoretical studies of laser-pulse interaction with a low-density absorber of the target, namely, with a porous substance having density close to the plasma critical density, are presented. On the basis of a vast cycle of experiments carried out in a number of laboratories, it is shown that the absorption of the laser radiation in porous media, including those with a density exceeding the critical one by at least a factor of 4 to 6, has a bulk nature and is distributed over the target depth. In particular, the laser-radiation absorption region in a porous substance with density 10−3–10−2 g/cm3 is extended into the target 400–100 μm, respectively. The coefficient of absorption of laser radiation with intensity 1014–1015 W/cm2 in porous substances, including those of the supercritical density, is 70–90%. Experiments have not shown enhanced (compared to a solid-state target) radiation intensity associated with a possible development of parametric instabilities in an extended laser plasma of low-density porous media, as well as noticeable contribution of fast electrons to the energy balance and their effect on the energy transfer. In this paper, theoretical models are developed explaining features of the laser-radiation absorption and energy transfer in porous media. These models are based on the phenomenon of laser-radiation interaction with solid components of a porous substance and plasma production inside pores and cells of the medium. The efficiency of energy conversion in the vicinity of the ignition threshold for the laser-greenhouse target is investigated in the case of an absorber having the above properties. Numerical calculations have shown that a thermonuclear-gain coefficient of 1 to 2 (with respect to the energy absorbed) is attained for a laser-radiation energy of 100 kJ. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
Externí odkaz: