High performance liner physics

Summary form only given. High performance, condensed matter, liner implosions powered by very high current drive provide an important capability for many physics experiments including shock physics, high magnetic field generation by flux compression, and quasi isentropic, P-dV, compression of materials ranging from solids to plasmas. Where large amounts of kinetic energy, high efficiency of conversion of electrical to kinetic energy, and/or high final implosion velocities are required, the traditional approach is to match the liner implosion time to the energy delivery time of the pulsed power driver. In this approach, the liner converges, arriving at the target while the power source continues to deliver current: late in, but not after, the end of the power pulse. This approach leads to driving the implosion with near-maximum current at small radius, maximizing the driving magnetic field, and maximizing the magnetic pressure through most of the implosion. This approach can lead to relatively high efficiency and minimum implosion time, but it also leads to high accelerations during most of the implosion. The principle obstacle to achieving high precision (accurately cylindrical) implosions is the development of magnetoRayleigh Taylor-like (MRT) instability at the magnetic field / liner interface. While it is the precision of the inner surface of the liner that is important in many applications, especially condensed matter experiments, growth of the MRT instability on the outer surface frequently results in distortions that penetrate through the full thickness of the liner, ruining the precision of the inner surface and making it unsuitable for many shock wave experiments. Instability growth increases with acceleration and is inhibited by material strength and by refining the surface precision, (to reduce the magnitude of initial perturbations). High precision implosions have been reported for cases in which the driving field was sufficiently low that the material at the liner / field interface is not melted, maintaining material strength throughout the liner. An approach to reaching these conditions will be discussed.