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Gandhinagar, India

Misra S.,Indian Institute of Technology Delhi | Mishra S.K.,Indian Institute of Plasma
Monthly Notices of the Royal Astronomical Society | Year: 2016

In this paper, the flight of micro (μ)-meteoroid in the day time earth environment has been discussed and the role of photoemission due to solar radiation, in addition to other relevant emission processes, viz. thermionic/charge desorption has been explored. Following Mendis et al., the meteoroid flight has been described by a consistent analytical model which manifests the continuity equations for the momentum, energy, charge and mass of micrometeoroids entering in the earth environment with a finite speed and at a finite angle. The altitude profiles of the characteristic features during flight, viz. surface heating, particle size, mass-loss, charging and its consequence on local atmospheric plasma has been examined in terms of the angle of entrance, entry speed, size, material work function/photoefficiency and incident solar flux. The numerical results show that the photoemission from micrometeoroid significantly contributes in meteoric electrons generation in its path in beginning and end phase of the flight; of course the energetics over the meteoroid in its travel is dominated by mass ablation process. © The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Saravanan P.,Indian Institute of Technology Bombay | Raja V.S.,Indian Institute of Technology Bombay | Mukherjee S.,Indian Institute of Plasma
Corrosion Science | Year: 2013

Plasma immersion ion implantation (PIII) of nitrogen has been performed on two austenitic stainless steels (with and without Mo addition) at three different temperatures namely, 250, 380 and 500. °C for 3. h. Grazing angle X-ray diffraction (GXRD) was carried out on the surface of the steels (both PIII treated and untreated). GXRD results suggest that PIII is more effective in Mo containing stainless steel (SS). The electrochemical corrosion studies examined through both by DC polarization and EIS technique in 3.5. wt.% NaCl reveals that, 3. h N-implantation at 250 and 380. °C improves the corrosion and pitting resistance of both the austenitic stainless steels under investigation. The effect N implantation on pitting resistance is seen more in the presence of Mo, than when it is not present in the SS. It is further emphasized that the pitting resistance of the alloys significantly deteriorates, when they are implanted at 500. °C. © 2013 Elsevier Ltd.

Bailung H.,Indian Institute of Plasma | Sharma S.K.,Indian Institute of Plasma | Nakamura Y.,Indian Institute of Plasma | Nakamura Y.,Yokohama National University
Physical Review Letters | Year: 2011

The experimental observation of Peregrine solitons in a multicomponent plasma with the critical concentration of negative ions is reported. A slowly amplitude modulated perturbation undergoes self-modulation and gives rise to a high amplitude localized pulse. The measured amplitude of the Peregrine soliton is 3 times the nearby carrier wave amplitude, which agrees with the theory. The numerical solution of the nonlinear Schrödinger equation is compared with the experimental results. © 2011 American Physical Society.

Saikia D.,Indian Institute of Plasma | Dutta P.,Institute of Advanced Study in Science and Technology | Sarma N.S.,Institute of Advanced Study in Science and Technology | Adhikary N.C.,Indian Institute of Plasma
Sensors and Actuators, B: Chemical | Year: 2016

In this work, we present a simple, ultrasensitive and rapid cost-effective sensing technique based on Mercaptosuccinic acid (MSA) capped CdTe/ZnS core/shell (CS) quantum dots (QD) for the detection of toxic Hg(II) in aqueous media. The present system demonstrations a remarkably low detection limit of one pico molar (pM) which is the best-reported work till date. Here, the CdTe/ZnS CS QD is synthesized by using a simple one pot aqueous method, and are characterized with the help of UV-vis, photoluminescence, XRD, TEM and FT-IR analysis. Due to the interaction between CS QDs and the heavy metal ions, the photoluminescence (PL) intensity of QDs quenches via excited state electron transfer mechanism, and is confirmed from cyclic voltammetry and zeta potential. CdTe/ZnS QDs are found to be highly selective for Hg (II) ions whereas the interference from other toxic metal ions is insignificant. The real time analysis was further carried out with drinking water and tap water solutions and the QDs show remarkably good quenching in these solutions. This is a very simple method for detection of Hg (II) ions in aqueous media and using this method, a prototype low-cost electronic equipment is further designed and fabricated. © 2016 Elsevier B.V. All rights reserved.

Sharma S.K.,Indian Institute of Plasma | Bailung H.,Indian Institute of Plasma
Physics of Plasmas | Year: 2010

Large amplitude ion acoustic compressive solitary waves are excited in a multicomponent plasma in the presence of a positive ion beam. The threshold amplitude, when steepening of the leading edge of the compressive pulse occurs, depends on the ion beam velocity. The Mach velocity and the amplitude of large amplitude compressive solitary waves are measured for different ion beam velocities. The amplification of the large amplitude compressive solitary wave is observed when the ratio of the ion beam velocity divided by the ion acoustic velocity is in the range of 0.8-1.4. The maximum amplitude of the density perturbation observed in the experiment is quite large (∼170%). © 2010 American Institute of Physics.

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