Nuclear fusion by laser radiation

Abstract

After briefly recalling the main features of laser-produced plasmas and the problems involved in the production of nuclear DD-reactions, the author deals with the fundamental data on heating mechanisms. Experimental results and heating limitations are then presented. Finally, a review of present and future possibilities of both laser and plasma parameters is given.

Higher-order Bragg diffraction by a periodic structure in a planar optical waveguide

“…When the laser and plasma frequencies become equal, at flux densities up to approximately 10 15 W/cm 2 an appreciable (> 25%) amount of the incident laser pulse is reflected off the plasma directly back along its path of incidence [12,13]. Fortunately, experimental evidence [14] indicates that as the flux density increases above 10 16 W/cm 2 , the fraction of incident light reflected decreases below 10%.…”

“…Only for a subsonic ablation front can appreciable effects due to momentum transfer precede the ablation front and result in any compression at the collapse centre. The counter situation of a supersonic ablation front results in quick heating of the entire pellet with little momentum directed towards the centre [ 12] . Such a supersonic front could be caused by suprathermal electrons and has been called "pellet pre-heat" by Nuckolls et al [1].…”

Fusion by laser-driven flame propagation in solid DT-targets

“…Then the condition for a net power gain is Evaluation of @t for a plasma where all the energy is thermal leads to the well-known conditions for a DT-mixture: nT > 6 X 10 13 cm" 3 s at T = 10 keV Now the condition for breakeven is simply given > 1 energy released incident absorbed energy In terms of 0t, it reads: Obviously, the above well-known numerical results do not apply directly to a non-stationary situation such as a flame propagation. 01 has now the specific meaning: energy released radiation losses +lthermal + kinetic) energy in the plasma (8) As in the Lawson derivation, the radiation term takes into account bremsstrahlung emission only. Re-absorption of this radiation will not be examined since at thermonuclear temperaturese.g.…”

“…We know from experiments on deuterium [6],and this is the second source of our ideas, -that the radiation-flame propagation into a solid target satisfies the requirement stated previously. Indeed, these experiments can be interpreted through either analytic [7,9] or numerical [8] hydrodynamical models. These involve a propagating rarefaction wave.…”

Early stages of light interaction with solids at extreme intensities

“…Nonlinear heat diffusion has been discussed previously by a number of authors (Zeldovich and Raizer 1966, Floux 1971, Bobin 1970, Caruso and Gratton 1969, Saltzman 1973. However, the effects of ionization, the temperature ranges in which electron conduction or radiation conduction predominate, and the precise location at which the shock emerges from the heat wave have not been discussed in earlier work.…”