Articles written in Pramana – Journal of Physics
Volume 45 Issue 5 November 1995 pp 439-451
Emission characteristics of a single heterostructure GaAs diode laser are reported using a simple driver circuit. It provides a single picosecond time duration optical pulse, a pulse train or a broad optical pulse depending on the amplitude and time duration of the electrical pump pulse. Results show that relaxation oscillation frequency depends on the amplitude of pumping current pulse as well as on some inherent property of diode laser, which seems to be the level of impurity in lasing medium. Variation of relaxation oscillation frequency with amplitude of current pulse shows only the qualitative agreement with the reported theoretical predictions.
Volume 55 Issue 5-6 November 2000 pp 773-779 Laser Plasmas, Contributed Papers
This paper presents the dynamics as well as the stability of laser produced plasma expanding across the magnetic field. Observation of some high frequency fluctuations superimposed on ion saturation current along with structuring in the pin hole images of x-ray emitting plasma plume indicate the presence of instability in the plasma. Two type of slope in the variation of x-ray emission with laser intensity in the absence and presence of magnetic field shows appearance of different threshold intensity of laser corresponding to each magnetic field at which this instability or density fluctuation sets on. This instability has been identified as a large Larmor radius instability instead of classical Rayleigh-Taylor (R-T) instability.
Volume 55 Issue 5-6 November 2000 pp 781-787 Laser Plasmas, Contributed Papers
An intense laser radiation (1012 to 1011 W/cm−2) focused on the solid target creates a hot (≥1 keV) and dense plasma having high ionization state. The multiple charged ions with high current densities produced during laser matter interaction have potential application in accelerators as an ion source. This paper presents generation and detection of highly stripped titanium ions (Ti) in laser produced plasma. An Nd:glass laser (KAMETRON) delivering 50 J energy (λ=0.53 µm) in 2.5 ns was focused onto a titanium target to produce plasma. This plasma was allowed to drift across a space of ∼3 m through a diagnostic hole in the focusing mirror before ions are finally detected with the help of electrostatic ion analyzer. Maximum current density was detected for the charge states of +16 and +17 of Ti ions for laser intensity of ∼1011 W/cm−2.
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