Particle-in-Cell Modeling of Laser Thomson Scattering in Low-Density Plasmas at Elevated Laser Intensities
Incoherent Thomson scattering is a non-intrusive technique commonly used for measuring local plasma density. Within low-density, low-temperature plasma's and for sufficient laser intensity, the laser may perturb the local electron density via the ponderomotive force, causing the diagnostic to become intrusive and leading to erroneous results. A theoretical model for this effect is validated numerically via kinetic simulations of a quasi-neutral plasma using the Particle-in-Cell technique.
Laser Thomson scattering for low-temperature plasmas
In recent years, low-temperature discharge plasmas with electron temperatures around a few eV have been actively studied and used for fundamental discharge physics research and industrial process applications. Here the electron density and temperature (and sometimes also the electron energy distribution function) are the most fundamental parameters that dictate the fates of these discharge plasmas and this information is of utmost importance. Laser Thomson scattering, which was developed for high-temperature plasmas in the early 1960s, has gained widespread use in the low-temperature plasma community since the late 1970s and has now matured as an established method of plasma diagnostics. Scattering diagnostic techniques for high-temperature plasmas have had to be modified to accommodate particular situations and constraints, such as laser perturbation of plasmas, low electron densities and the presence of material surfaces near to the plasmas. In this review, starting from a basic description of the technique, we outline some of the most salient results, which would not have been obtained without it, in discharges ranging from high-pressure to low-pressure gases, and near to material surfaces. Also, the signal-to-noise ratio and future potential of the method are discussed.
Proliferative kidney disease: first reported outbreak in North America
Abstract. Proliferative kidney disease (PKD) was diagnosed in rainbow trout, Salmo gairdneri Richardson, at the Hagerman, Idaho, State Fish Hatchery. Wild fish from Riley Creek, one of the hatchery water supplies, were infected with PKD organisms. Clinical signs, gross pathology and histopathology of affected fish were typical of those reported for PKD in salmonids from European hatcheries. In addition to lesions normally seen, we observed a severe vasculitis and occlusion of renal and hepatic vessels. Ultrastructure of the PKD organism and possible inclusion body production sites are described. The disease outbreak was complicated by the presence of other infectious diseases. This is the first recorded outbreak of PKD in North America.