Driven by pulsed current

a metal wire explodes due to joule energy deposition. Plasmas generated by explosion diffuse rapidly into ambient gases and is condensated into nanoparticles. Investigation on characteristics of plasmas is important to understand the mechanism of formation of the nanoparticles. In this paper

experiments of microsecond electrical explosion（2～10 cm in length

0.1～0.4 mm in diameter） in 0.1～1.0 MPa argon gas were carried out with electrical and optical measurements. The influences of experimental parameters

including ambient pressures

wire size

and applied voltage

on the energy deposition were obtained and analyzed. Moreover

using multi-frame photographs and shadowgraphs

the spatial distribution and diffusion characteristics were observed. The energy deposition was found to increase with pressures and applied voltage and to decrease with wire sizes. When the energy deposition was insufficient

the plasma is inhomogeneous along the axial direction and expansion velocity is relative low. Increasein energy deposition will suppress the non-uniformity of spatial distribution and improve the expansion velocities.