Laboratory simulation of high-altitude disruptive effects

Disturbed ionospheric and space conditions are simulated and studied with laser-produced plasmas in the Naval Research Laboratory PHAROS Laser Facility. Intense laser pulses, containing up to 1500 joules in 3 ns, produce plasma energy densities over 1 Gigajoule/gm, comparable to those occurring in nuclear detonations. The expansion of these plasmas through a background ambient magnetized plasma simulate high-altitude nuclear explosion (HANE) effects, as well as supernova shock and other energetic space plasma conditions. In this paper we focus on effects, such as blast-waves and plasma instabilities leading to nonuniform and disturbed space environments that can affect space-based communications and sensor systems. The laser experiment is useful for investigation of mechanisms accompanying less energetic active space experiments also, such as chemical releases and particle beam injections. In this connection, we describe laboratory experiments demonstrating the existence of the large Larmor radius (LLR) instability which caused the plasma structuring observed in the 1985 magnetospheric AMPTE-barium release experiment. Extensions of the LLR-instability experiment into the nonlinear regime and towards parameters scaled to model very high-altitude nuclear explosions (VHANEs) and several CRRES chemical releases are outlined. We also discuss space related laboratory experiments on blast-waves, plasma jetting, MHD turbulence. Finally, the NRL Space Chambermore » program is described.« less