Parameter study of a pulsed capillary discharge waveguide

Slow pulsed capillary discharges are currently under investigation for use as plasma channel waveguides in laser-wakefield acceleration and XUV generation. A parameter study is performed on this device using a combination of 2 models, namely a non-local thermal equil. (non-LTE) plasma model and a wall temp. model that is coupled to it. This model was validated against expts. Two parameters are varied, the initial d. and the channel radius. These parameters have a strong influence on the guiding properties. The results of this parameter study can be summarized in a single, empiric formula describing the matched spot size as a function of the initial d. and the channel radius. This formula is expected to give a good prediction of the matched spot size, provided that no wall ablation occurs, diffusion is limited and that the current pulse is sufficient in amplitude and duration for formation of a well-ionized, stable plasma. This was verified for the parameter range studied here. [on SciFinder (R)]