A QUASI-1D MODEL OF THERMONUCLEAR IGNITION OF DENSE DT MIXTURE DRIVEN BY PROTON BEAMS
K. V. Khishchenko, A. A. Charakhch’yan
VANT. Ser.: Mat. Mod. Fiz. Proc 2015. Вып.1. С. 3-15.
We consider a cylindrical DT target of thickness 2H and density ρ0 ≤ 100ρs, where ρs ≈ 0,22 g/cm3 is the solid DT density under atmospheric pressure and temperature of 4K. The target is supposed to be enclosed in a heavy magnetized shell preventing lateral expansion and heat transfer from the fuel to the shell. The target is ignited at both ends simultaneously by two equivalent monoenergenic proton beams with 1MeV kinetic energy. The beam pulse intensity and duration are 1019/cm2 and 50 ps or 1018/cm2 and 500 ps, respectively. We use a 1D one-velocity two-temperature hydrodynamic model with a wide-range equation of state of the fuel, electron and ion heat conductivities, DT reaction kinetics, self-radiation of plasma and its heating by α-particles. The latter is assumed to be the governing target ignition mechanism. The flight of α-particles beyond the fuel is incorporated within the track method. We propose a modification of this method, which approximates the known Cauchy problem for a homogeneous steady-state kinetic equation in the Fokker-Planck approximation. The paths of α-particles are constrained by a cylindrical surface of a given radius, which is the method’s parameter and which is identified with the target radius and the proton beam radius. This quasi-1D model allows us to estimate the ignition energy and the target mass. For the initial fuel density of ρ0 = 100ρs, the estimated ignition energy is approximately 10 times smaller than the corresponding estimate for the problem with a beam radius much smaller than the target size. Keywords: cylindrical inertial confinement fusion target, ignition energy, burnup factor, track method, Fokker-Planck approximation.
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English
