• C P Navathe

      Articles written in Sadhana

    • An indigenously developed electronic control system for Langmuir-Blodgett film deposition set-up

      C P Navathe B L Dashora Archana Jaiswal D S Thakur U N Roy L M Kukreja

      More Details Abstract Fulltext PDF

      An indigenous and simple electronic control system for Langmuir-Blodgett (LB) film deposition set-up has been developed. This set-up consists of a microstepping circuit to drive the stepper motors with precision and smooth motion, essential for controlled movement of the barriers and substrate in the LB set-up. Linear variable differential transformer (LVDT)-based displacement measuring device has been developed and used to measure the surface pressure of the monolayer material spread on the water surface. A control program is written which incorporates all operational modes required to drive the set-up and to acquire the datain situ using a set of user-friendly commands. This control set-up has been successfully used to plot the pressure-area isotherm of various amphiphilic compounds such as ferric stearate, zinc arachidate etc. and for deposition of ordered LB films of ferric stearate.

    • Control and analysis software for a laser scanning microdensitometer

      H R Bundel C P Navathe P A Naik P D Gupta

      More Details Abstract Fulltext PDF

      A PC-based control software and data acquisition system is developed for an existing commercial microdensitometer (Biomed make model No. SL-2D/1D UV/VIS) to facilitate scanning and analysis of X-ray films. The software is developed in Labview, which includes operation of the microdensitometer in 1D and 2D scans and analysis of spatial or spectral data on X-ray films, such as optical density, intensity and wavelength. It provides a user-friendly Graphical User Interface (GUI) to analyse the scanned data and also store the analysed data/image in popular formats like data in Excel and images in jpeg. It has also on-line calibration facility with standard optical density tablets. The control software and data acquisition system is simple, inexpensive and versatile.

    • Development of single frame X-ray framing camera for pulsed plasma experiments

      J Upadhyay J A Chakera C P Navathe P A Naik A S Joshi P D Gupta

      More Details Abstract Fulltext PDF

      A single-frame X-ray framing camera has been set up for fast imaging of X-ray emissions from pulsed plasma sources. It consists of two parts, viz. an X-ray pin-hole camera using an open-ended microchannel plate (MCP) detector coupled to a CCD camera, and a high voltage short duration gate pulse for the MCP. The camera uses a 10-Μm pin-hole aperture for imaging on the MCP detector with a magnification of 6 X. The high voltage pulser circuit generates a pulse of variable duration from 5 to 30 ns (at 70% of peak amplitude) with variable amplitude from 800 V to 1.25 kV, and is triggered through a laser pulse synchronized with the event to be recorded. The performance of the system has been checked by recording X-ray emission from a laser-produced copper plasma. A reduction factor of ∼ 6.5 is seen in the dark current contribution as the MCP gate pulse is decreased from 250Μs to 5 ns duration.

    • Design, development and performance characteristics of a large aperture disc amplifier for high power Nd: Glass laser chain

      M P Kamath P K Tripathi A P Kulkarni R Chandra A S Joshi C P Navathe P D Gupta

      More Details Abstract Fulltext PDF

      A large aperture disc amplifier has been designed, set-up and characterized for its performance on small signal gain, spatial variation of gain, and thermal recovery time. This amplifier, consisting of three elliptical Nd: phosphate glass discs of size 214 × 114 × 20 mm mounted at Brewster angle and pumped by ten xenon filled flash lamps of 600 mm arc length, provided a small signal gain of 6 at electrical pump energy of 36 kJ (in a pulse of 450 𝜇s) using an in-house developed dual-polarity capacitor bank based power supply. It was coupled to a high power Nd: phosphate glass laser chain and a maximum output pulse energy exceeding 100 J in a 1·5 ns (FWHM) pulse has been measured. A dry nitrogen gas based cooling system was developed for cooling the glass discs with a thermal recovery time of ∼ 20 minutes.

    • Generation of intense soft X-rays from capillary discharge plasmas

      Y B S R Prasad S Nigam K Aneesh S Barnwal P K Tripathi P A Naik C P Navathe P D Gupta

      More Details Abstract Fulltext PDF

      X-ray lasing through high voltage, high current discharges in gas filled capillaries has been demonstrated in several laboratories. This method gives highest number of X-ray photons per pulse. The fast varying current and the j x B magnetic force compress the plasma towards the axis forming a hot, dense, line plasma, wherein under appropriate discharge conditions lasing occurs. At Laser Plasma Division, RRCAT, a program on high voltage capillary discharge had been started. The system consists of a 400 kV Marx bank, water line capacitor, spark gap and capillary chamber. The initial results of the emission of intense short soft X-ray pulses (5–10 ns) from the capillary discharge are reported.

  • Sadhana | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.