V N Rai
Articles written in Pramana – Journal of Physics
Volume 52 Issue 1 January 1999 pp 49-65
Development of a single and multichannel biplanar vacuum photodiode for x-ray detection is reported, which has been used to study the x-ray emission from laser produced plasma expanding across an externally applied magnetic field. Two to three times enhancement in x-ray emission has been observed which was found correlated with decrease in size of the x-ray emitting plasma plume (expansion velocity of plasma). Experimental observations were found in close agreement with the analytical model based on an increase in plasma density as a result of plasma confinement in magnetic field. Temporal evolution of x-ray emission indicates that recombination radiation seems to be playing an important role in x-ray enhancement.
Volume 65 Issue 6 December 2005 pp 1075-1083
Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in emission intensity was noted for inter-pulse delay of ∼2–3 μs for all the elements. The experimental observations were qualitatively explained on the basis of absorption of second laser pulse in the pre-formed (by first laser) coronal plasma by inverse Bremsstrahlung process, which were found responsible for the excitation of more ions and atoms in the plasma. This process starts as the plasma scale length becomes greater than the laser wavelength. This study further indicated the suitability of this technique in the field of elemental analysis