DT ignition in a Z pinch compressed by an imploding liner

Abstract

It has been shown [1] that an m = 0 instability of a Z-pinch carrying a current of the order of 10 MA, with a rise time inferior to 10 nsec can generate a spark capable of igniting a fusion detonation in the adjacent DT plasma channel. A possible method for generating such currents, necessary for the implosion of an initial large radius, low temperature Z-pinch, can be a radial implosion of a cylindrical fast liner. The problem has been addressed in a previous publication, [2][3][4][5], without considering the role played by an initially impressed m = 0 perturbation, a mechanism indispensable for the generation of a spark. The liner/Z-pinch dynamics can be solved at several levels of physical model completeness. The first correspond to a zero-dimensional model in which the liner has a given mass per cm length and a zero thickness, the plasma is compressed adiabatically and is isotropic, there are no energy losses and no Joule heating. The second level is one-dimensional. The Z-pinch plasma is described by the full set of MHD, 2 fluid equations. The liner is treated first as thin and incompressible and subsequently it is assumed that it has a finite thickness and is composed of a heavy ion plasma, having an artificial but realistic EOS. Both plasma and liner are considered uniform in the Z-direction and only D-T reactions are considered. We shall show that, given sufficient energy and speed of the liner, the Z-pinch can reach a volume ignition. The third level is two-dimensional. Plasma and liner are treated as in the 2nd level but either the Z-pinch or the liner is perturbed by an m = 0 non-uniformity. Provided the liner energy is high enough and the initial m = 0 perturbation is correctly chosen, the final neck plasma can act as a spark for D-T ignition.