Abstract
Abstract In this paper we consider laser intensities greater than $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}10^{16}\ \mathrm{W\ cm}^{-2}$ where the ablation pressure is negligible in comparison with the radiation pressure. The radiation pressure is caused by the ponderomotive force acting mainly on the electrons that are separated from the ions to create a double layer (DL). This DL is accelerated into the target, like a piston that pushes the matter in such a way that a shock wave is created. Here we discuss two novel ideas. Firstly, the transition domain between the relativistic and non-relativistic laser-induced shock waves. Our solution is based on relativistic hydrodynamics also for the above transition domain. The relativistic shock wave parameters, such as compression, pressure, shock wave and particle flow velocities, sound velocity and rarefaction wave velocity in the compressed target, and temperature are calculated. Secondly, we would like to use this transition domain for shock-wave-induced ultrafast ignition of a pre-compressed target. The laser parameters for these purposes are calculated and the main advantages of this scheme are described. If this scheme is successful a new source of energy in large quantities may become feasible.
Highlights
Inertial fusion energy (IFE) is based on high compression[1,2,3]
Shock waves in laser plasma interactions[7] have played an important role in the study of IFE
For laser intensities in the range 1012 W cm−2 < IL < 1016 W cm−2 and nanosecond pulse durations a hot plasma is created. This plasma exerts a high pressure on the surrounding material, leading to the formation of an intense shock wave moving into the interior of the target
Summary
Inertial fusion energy (IFE) is based on high compression[1,2,3]. The reasoning is that it is energetically cheaper to compress rather than to heat and the nuclear reactions are proportional to the density squared. In order to ignite a DT target with significantly less than a few MJ of energy, it was suggested[13, 14] to separate the drivers that compress the target from those that heat the target This idea is called fast ignition (FI), and triggers not in a central spark, but in a secondary interaction of an igniting driver of a very short duration, such as a multiPetawatt (PW) laser beam. (9) the use of an extra laser-induced shock wave created by the same lasers that compressed the target in order to ignite the target was suggested[25]. For laser intensities in the range 1012 W cm−2 < IL < 1016 W cm−2 and nanosecond pulse durations a hot plasma is created This plasma exerts a high pressure on the surrounding material, leading to the formation of an intense shock wave moving into the interior of the target. The paper is concluded with a short summary and discussion
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