• Bijendra Singh

      Articles written in Pramana – Journal of Physics

    • Enhanced performance of a wide-aperture copper vapour laser with hydrogen additive in neon buffer gas

      Bijendra Singh V V Subramaniam S R Daultabad Ashim Chakraboty

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      A wide-aperture copper vapour laser was demonstrated at $\sim 10$ kHz rep-rate with hydrogen additive in its buffer gas. Maximum power in excess of $\sim 50$ W (at 10 kHz) was achieved by adding 1.96% hydrogen to the neon buffer gas at 20 mbar total gas pressure. This increase in output power was about 70% as compared to $\sim 30$ W achieved with pure neon at 5.5 kHz rep-rate. The 70% enhancement achieved was significantly higher than the maximum reported value of 50% so far in the literature. The enhancement was much higher (about 150%) as compared to its 20 W power at 10 kHz rep-rate using pure neon as the standard CVL operation.

    • Enhanced performance of a repetitively pulsed 130 mJ KrF laser with improved pre-ionization parameters

      N S Benerji A Singh N Varshnay Bijendra Singh

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      Studies related to the effect of pre-ionizer on laser output energy of a repetitively pulsed KrF laser are presented. The dependence of laser output energy, spectral width and beam spot homogeneity on pre-ionization parameters, namely its current and voltage rise time are reported here. Here, effectiveness of pre-ionization is optimized by improving pre-ionization current and rise time of the pump pulse of the automatic UV pre-ionizer KrF laser. It is observed that by increasing pre-ionization current from 6 kA to 10.6 kA, the output energy increases by about 30% (from 100 to 130 mJ). It is also observed that the emission spectral width reduces by almost 60% by increasing the pre-ionization current. Regular homogeneous and well-developed beam spot (nearly Hat-Top profile) was achieved under these optimized conditions.

    • Design and performance characteristics of a krypton chloride (𝜆 = 222 nm) excimer laser

      N S Benerji N Varshnay A Singh Bijendra Singh

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      Development of a discharge-pumped krypton chloride (KrCl) laser operating at 222 nm wavelength is demonstrated. In this paper the design, successful realization and operating characteristics of KrCl excimer laser are reported. The laser is driven by a simple and efficient excitation technique using automatic UV pre-ionization with discharge-pumped self-sustained capacitor– capacitor (C–C) energy transfer circuit. The experimental investigations including output laser energy, temporal pulse parameters, emission spectra and beam profile of the KrCl laser were recorded. For high repetition rate operation, in-built, compact gas circulation system using tangential blower was incorporated. The laser was operated at 25 kV discharge voltage, gas mixture of 5 mbar HCl, 160 mbar kypton and neon as balance with a total gas pressure of ∼2.5 bar. These experiments produced an efficient and reliable output energy of 25 mJ from an active volume of 60 cm3.

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