Generation of C6+ in a spark-discharge coupled laser plasma

By coupling a spark discharge into a laser-generated carbon plasma, fully-stripped carbon ions with a relatively low laser pulse energy are observed. When spark-discharge energy of ∼750mJ is coupled to the carbon plasma generated by ∼50mJ laser pulse (wavelength 1064 nm, pulse width 8 ns, intensity 5×109W∕cm2), enhancement in the total ion charge by a factor of ∼6 is observed, along with the increase of maximum charge state from C4+ to C6+. Spark coupling to the laser plasma significantly reduces the laser pulse energy required to generate highly-charged ions. Compared to the laser carbon plasma alone, the spark discharge increases the intensity of the spectral emission of carbon lines, the electron density ne, and the electron temperature Te. The effective ion plasma temperature associated with translational motion along the plume axis Tieff is calculated from the ion time-of-flight signal.