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

Abstract

When a laser light flux ϕ impinges on a solid target a radiation wave propagates which transforms the material into a hot plasma. The structure of the hot parts is known to show an overdense hot stationary deflagration structure followed by a nearly isothermal rarefaction. The temperature T of the hot plasma varies as (ϕ/nec)2/3, nec being the cut-off density. Then the ratio of the energy of the thermonuclear reaction products to the sum of the radiated energy plus the (kinetic + thermal) energy in the plasma is readily calculated for DT as a function of the duration of the interaction. For a 30% efficiency of the energy-conversion cycle, typical figures for a positive energy balance are ϕ = 5 × 1014W/cm2 (T = 108 °K), τ = 10−7 s for Nd glass, and ϕ = 5 × 1012W/cm2 (T = 108°K), τ = 10−5 s for CO2 laser. For both cases, the required laser energy density is a few 107 joules/cm2. In the latter case, a megagauss confining field could be successfully used to maintain a one-dimensional flame-propagation geometry.

On the ignition of a self-sustained fusion reaction in a dense DT plasma

“…This scheme demands much of laser pulse shaping and the fraction of burned DT fuel is severely restricted by the short time of the pellet expansion (Brueckner & Jorna 1974). There are a number of proposals for employing magnetic fields and wall confinement in order to increase the inertial confinement time (Dawson 1964;Bobin, Colombant & Tonon 1971;Pashinin & Prokhorov 1971) or to decrease the energy losses (Pashinin & Prokhorov 1972;Prokhorov, Anisimov & Pashinin 1976), but the estimates of the corresponding energy thresholds still give values which are too high.…”

Quasi-three-dimensional hydrodynamics of the corona region of laser irradiation of a slab

“…is the transient isothermal sound speed and M i is the ion mass, [33,34] and the ionization degree formula of the corona region Z = 20 3 [A(T/keV)] 1/3 is used, where A is the atomic number of the considered element.…”

Analytical model for Rayleigh-Taylor instability in conical target conduction region

“…The authors consider the equation for the sound speed as C 2 s = ZT /M i , and use the ionization degree formula of the corona region: Z = 20 3 [A(T /keV)] 1/3 , where A is the atomic number of the considered element and M i is the proton mass. [44,45] Hence, the authors obtain the following equation:…”