After the theory of dynamic double layers in laser-produced plasmas arrived at several significant results in agreement with measurement, including particle acceleration, a clarification was given to the paper by Bryant et al. (1992) negating such acceleration. The discrepancy seems to be in the definition of static double layers in contradiction with dynamic double layers that are created in laser-induced plasma. We present here new results on the acceleration of electrons in a laser-irradiated plasma by double layer mechanisms. A simple analytical example is given.
A new concept of hot plasma confinement in a miniature magnetic bottle induced by circularly polarized laser light is suggested. Magnetic fields generated by circularly polarized laser light may be of the order of megagauss. In this configuration the circularly polarized laser light is used to obtain confinement of a plasma contained in a good conductor vessel. The poloidal magnetic field induced by the circularly polarized laser and the efficiency of laser absorption by the plasma are calculated. The confinement in this scheme is supported by the magnetic forces. The Lawson criterion for a DT plasma might be achieved for number density n = 5.1021 cm-3 and confinement time τ = 20 ns. The laser and plasma parameters required to obtain an energetic gain are calculated.
Steadystate and timeresolved fluorescence study of some dyes in polymer microspheres showing morphology dependent resonancesA new method of measuring the free-surface velocity via soft x-ray shadowgraphy is presented. Using that method, the shock-wave pressure was deduced. In addition, a new method of measuring the Mie scattering of the debris from laser-induced spa11 in aluminum is also presented. The data have yielded the distribution of the debris radii in the range of l-7 pm. Furthermore, it was shown that the smaller particles are the faster ones. 0 1995 American Znstitute ofP?zysics.
The reflectivity of tungsten-carbon (W-C) multilayers, heated by 7 ns Nd-YAG laser pulses was measured using soft x-ray radiation at 4.4 nm. The reflectivity permanently increased and the Bragg angle decreased after heating the multilayer at fluences of 0.3 J/cm2. The reflectivity increase was achieved in a narrow domain of heating fluences. A quantitative model based on laser absorption and heat transport, that explains the melting phenomenon of tungsten and the heating to a temperature where graphitization is possible in the carbon layers, is presented. The two phenomena: (a) increase in x-ray reflectivity and (b) expansion of the multilayer mirror can be explained by the laser heating. The improvement of reflectivity is caused by the smoothening of the tungsten layers due to melting, while the change in the spacing is attributed to the carbon phase transition (graphitization).
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