Symmetrically converging plane thermonuclear burn waves

Abstract

Five variants of a one-dimensional problem on synchronous bilateral action of two identical drivers on opposite surfaces of a plane layer of DT fuel with the normal or five times greater initial density, where the solution includes two thermonuclear burn waves propagating to meet one another at the symmetry plane, are simulated. A laser pulse with total absorption of energy at the critical density (in two variants) and a proton bunch that provides for a nearly isochoric heating (in three variants) are considered as drivers. A wide-range equation of state for the fuel, electron and ion heat conduction, self-radiation of plasma and plasma heating by α-particles are taken into account.In spite of different ways of ignition, various models of α-particle heat, whether the burn wave remains slow or transforms into the detonation wave, and regardless of way of such a transformation, the final value of the burn-up factor depends essentially on the only parameter Hρ 0 , where H is the half-thickness of the layer and ρ 0 is the initial fuel density. This factor is about 0.35 at Hρ 0 ≈ 1 g cm −2 and about 0.7 at Hρ 0 ≈ 5 g cm −2 . The expansion stage of the flow (after reflecting the burn or detonation wave from the symmetry plane) gives the main contribution in forming the final values of the burn-up factor and the gain at Hρ 0 ≈ 1 g cm −2 and increases them approximately two times at Hρ 0 ≈ 5 g cm −2 . In the case of the proton driver, the final value of the gain is about 200 at Hρ 0 ≈ 1 g cm −2 and about 2000 at Hρ 0 ≈ 5 g cm −2 . In the case of the laser driver, the above values are four times less in conformity with the difference between the driver energies.