SELF-SIMILAR IMPLOSIONS AND EXPLOSIONS OF RADIATIVELY COOLING GASEOUSMASSES

A self-similar solution of the gas dynamics equations with heat conduc tion, which describes homologous contraction and expansion of gaseous masses with a free external boundary, is investigated in detail. As a primary application, implosion of deuterium-tritium (DT) fuel in inert ial confinement fusion targets is considered. For strongly non-adiabat ic implosions the self-similar solution predicts that the flow pattern should approach an asymptotical regime in which it ceases to depend o n the initial entropy. For DT masses relevant to inertial confinement fusion (ICF) this regime begins to dominate at alpha U-im greater than or similar to 6 x 10(8) cm/s, where alpha = p/p(deg) is the fuel isen trope parameter, and Ui, is its implosion velocity. The solution has a lso a branch which describes an asymptotical regime of explosive expan sion after an ultra-fast initial heating to a strongly radiating state . (C) 1998 American Institute of Physics.