• U Chakravarty

      Articles written in Pramana – Journal of Physics

    • Electric field enhancement at multiple densities in laser-irradiated nanotube plasma

      U Chakravarty P A Naik P D Gupta

      More Details Abstract Fulltext PDF

      The electric field enhancement inside a nanotube irradiated by intense ultrashort laser pulse ($\ll 1$ ps) is calculated. The hollowness of the nanotubes determines the field enhancement and the electron density at which such structures exhibit resonance. The electric field in a nanotube plasma is shown to be resonantly enhanced at multiple densities during the two phases of interaction: the ionization phase and the hydrodynamic expansion phase. It is further shown that by a proper choice of hollowness of the nanotubes, a continued occurrence of the resonance over a longer time can be achieved. These properties make nanotubes efficient absorbers of intense ultrashort laser pulses.

    • Spectral analysis of K-shell X-ray emission of magnesium plasma produced by ultrashort high-intensity laser pulse irradiation

      V Arora U Chakravarty Manoranjan P Singh J A Chakera P A Naik P D Gupta

      More Details Abstract Fulltext PDF

      Spectral analysis of K-shell X-ray emission of magnesium plasma, produced by laser pulses of 45 fs duration, focussed up to an intensity of ∼1018 W cm-2, is carried out. The plasma conditions prevalent during the emission of X-ray spectrum were identified by comparing the experimental spectra with the synthetic spectra generated using the spectroscopic code Prism-SPECT. It is observed that He-like resonance line emission occurs from the plasma region having sub-critical density, whereas K-𝛼 emission arises from the bulk solid heated to a temperature of 10 eV by the impact of hot electrons. K-𝛼 line from Be-like ions was used to estimate the hot electron temperature. A power law fit to the electron temperature showed a scaling of $I^{0.47}$ with laser intensity.

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