Laser focusing and multiple ionization of argon in a hydrogen plasma channel created by a pre-pulse

Complete text of publication follows. A model for plasma channel formation by a laser pre-pulse in a low z gas (Hydrogen) embedded with high z atoms (Argon) is developed. The laser of intensity I ≅ 1014W / cm2 ionizes hydrogen atoms fully whereas Argon atoms are ionized only singly. After the first pulse is gone, plasma expands on the time scale of a nanosecond to produce a hydrogen plasma channel with minimum density on the axis. A second intense short pulse laser of intensity I ≥ 1016W / cm2 gets focused. It tunnel ionizes the remaining Argon. The Argon acquires Ar8+ charge state after loosing 8 ions and acquires Neon like configuration and could emit X-rays.