  We describe the measurements to control the morphology and hence the
characteristics of a picosecond laser produced chromium plasma plume upon
double-pulse (DP) irradiation compared to its single-pulse (SP) counterpart. DP
schemes are realized by employing two geometries wherein the inter-pulse delay
($\tau_p$) in the collinear geometry and the spatial separation ($\Delta x$)
are the control parameters for schemes DP$_1$ and DP$_2$ respectively. The
aspect ratio (plume length/plume width) decreases upon increasing parameters
such as pressure, delay between pulses and the energy of the second pulse in
DP1 scheme. Interestingly, the expansion conditions of the plume which occurs
at higher pressures for SP scheme could be recreated in DP1 scheme for a lower
pressure $\sim$ 10$^{-6}$ Torr. This could be potentially applied for immediate
applications such as high harmonic generation and quality thin film production.

Plasma Physics