Raja Ramanna Center for Advanced Technology
Raja Ramanna Center for Advanced Technology
News Article | February 21, 2017
India has the ability to develop a space station – yet it’s still unclear whether it will. This is the statement of Indian Space Research Organization chairman A.S. Kiran Kumar at the foundation day ceremonies of the Raja Ramanna Center for Advanced Technology in the country on Monday, Feb. 20. According to Kumar, they are still in talks about the immediate benefits of a manned space mission, citing the need for funds and time as to why the country has not decided on when to invest on a space station. “The day the country takes the decision, we will ‘ok’ the project,” he said in an India Times report, emphasizing that the project requires long-term thinking along with policy and funding support. A space station is a crewed satellite that is designed to stay in low Earth orbit for long periods of time, studying the results and consequences of long-term spaceflight in humans. Today only one space station is operating: the International Space Station, a joint effort of NASA, Russia, and the European Union. Kumar added that the Indian space agency was also considering partnering with the private space sector to enhance its satellite-launching ability, and mentioned the need to up the number of satellites that monitor land and weather conditions in India and fortify its communication network. He pointed to a need to conduct about 18 launches every year, or triple its current capacity. In a commentary, LiveMint pointed to why ISRO managed to deliver on such groundbreaking level that few other government agencies of its kind was able to. “ISRO’s current chairman, A.S. Kiran Kumar, is also chairman of the Space Commission and secretary of DOS [Department of Space]. This setup has promoted vertical integration between policymakers — who are in a position to understand the nature of the long-term projects ISRO undertakes — and those delivering the end results,” the publication noted. ISRO is fresh from the success of its record-breaking 104-satellite launch aboard a single rocket. Last Feb. 15, it launched the rocket from Sriharikota's Satish Dhawan Space Center in Andhra Pradesh. The Polar Satellite Launch Vehicle-C37 carried a payload of 103 nano-satellites coming from India as well as Kazakhstan, Israel, the United States, the Netherlands, and Switzerland. It also transported the Earth observation instrument Cartosat-2. No other nation has so far launched 104 satellites from a single rocket in one go, making the feat a huge and important one for ISRO. The Russian space agency Roscosmos held the previous record at 37 satellites in one rocket launch. India also hiked its spending on space technology and research, believing that space exploration investments will yield positive returns for the country. It is mostly gearing up for two missions, each leading to Mars and Venus, with the Mars Orbiter Mission II possibly including a lander and likely to launch in 2021. India’s Mars Orbiter Mission arrived in the planet’s orbit back in September 2014, its first-ever interplanetary mission that came with a $74 million price tag. The nation finds a Mars mission rival in its Asian neighbor China, which aims to send a Mars probe by 2020 after a probe on the far side of the moon by late 2018. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
Saini R.K.,Raja Ramanna Center for Advanced Technology |
Das K.,Raja Ramanna Center for Advanced Technology
Journal of Physical Chemistry B | Year: 2012
Picosecond spectral relaxation of the excited state of curcumin in a binary solvent mixture of toluene and MeOH (or MeOH-d4) is reported with an instrument time resolution of ∼40 ps. With increasing mole fraction of MeOH (MeOH-d4) the fluorescence intensity and lifetime of curcumin increase to a maximum at a MeOH (MeOH-d4) mole fraction of 0.14 (0.40) and then decrease. In addition, fluorescence decays taken at the red edge of the emission spectrum started to show measurable rise times (170 to 30 ps), the magnitude of which decreased gradually with increasing alcohol mole fraction. This is attributed to the modulation of the nonradiative rates associated with the excited-state intermolecular H(D) bonding between the pigment and the polar protic solvent. As a consequence, the solvation times in the binary mixture were observed to slow down considerably (20-40 times) at certain solvent compositions compared to neat MeOH. The fact that three Gaussian components are needed to adequately represent the steady-state emission spectra and two isosbestic points are observed in the time-resolved area normalized emission (TRANE) spectra of the pigment suggests the existence of at least three species in the excited state. The observed results are rationalized with a scheme where ground state of the pigment exists in free and H-bonded (intermolecular) state. Optical excitation results in a mixture of these species in the excited state and the observed spectral relaxation correspond to the conversion of these two species in to a third species where dipolar solvation and intermolecular H-bonding have been optimized. © 2012 American Chemical Society.
Biswas B.,Raja Ramanna Center for Advanced Technology
Review of Scientific Instruments | Year: 2013
A solenoid magnetic field model is presented that describes the on axis field by a parameter of its hard edginess and axial half-width at half-maximum field, which universally define its spherical aberration without solving the ray equation. The model shows an increase in spherical aberration from real soft edge fields to hard edge models, as used in beam tracking. It compares well with existing field models. It simply and accurately finds the spherical aberration in many types of solenoids. © 2013 AIP Publishing LLC.
Saini V.K.,Raja Ramanna Center for Advanced Technology
Applied Optics | Year: 2013
Laser-induced optogalvanic (OG) signal oscillations detected in miniature neon glow discharge plasma are investigated using a discharge equivalent-circuit model. The damped oscillations in OG signal are generated when a pulsed dye laser is tuned to a specific neon transition (1s5 ? 2p2) at 588.2 nm under the discharge conditions where dynamic resistance changes its sign. Penning ionization via quasi-resonant energy transfer collisions between neon gas atoms in metastable state and sputtered electrode atoms in ground state is discussed to explain the negative differential resistance properties of discharge plasma that are attributed to oscillations in the OG signal. The experimentally observed results are simulated by analyzing the behavior of an equivalent discharge-OG circuit. Good agreement between theoretically calculated and experimental results is observed. It is found that discharge plasma is more sensitive and less stable in close vicinity to dynamic resistance sign inversion, which can be useful for weakoptical- transition OG detection. © 2013 Optical Society of America.
Kamal C.,Raja Ramanna Center for Advanced Technology |
Ezawa M.,University of Tokyo
Physical Review B - Condensed Matter and Materials Physics | Year: 2015
Recently, phosphorene, a monolayer honeycomb structure of black phosphorus, was experimentally manufactured and has attracted rapidly growing interest. Motivated by phosphorene, here we investigate the stability and electronic properties of the honeycomb structure of the arsenic system based on first-principles calculations. Two types of honeycomb structures, buckled and puckered, are found to be stable. We call them arsenenes, as in the case of phosphorene. We find that both buckled and puckered arsenenes possess indirect gaps. We show that the band gap of puckered and buckled arsenenes can be tuned by applying strain. The gap closing occurs at 6% strain for puckered arsenene, where the bond angles between the nearest neighbors become nearly equal. An indirect-to-direct gap transition occurs by applying strain. Specifically, 1% strain is enough to transform puckered arsenene into a direct-gap semiconductor. We note that a bulk form of arsenic called gray arsenic exists which can be used as a precursor for buckled arsenene. Our results will pave the way for applications to light-emitting diodes and solar cells. © 2015 American Physical Society.
Roy S.B.,Raja Ramanna Center for Advanced Technology
Journal of Physics Condensed Matter | Year: 2013
We show that the first order magneto-structural phase transitions observed in various classes of magnetic solids are often accompanied by useful multi-functional properties, namely giant magneto-resistance, magneto-caloric effect and magneto-striction. We highlight various characteristic features associated with a disorder influenced first order phase transition namely supercooling, superheating, phase-coexistence and metastability, in several magnetic materials and discuss how a proper understanding of the transition process can help in fine tuning of the accompanied functional properties. Magneto-elastic coupling is a key element in this first order phase transition, and methods need to be explored for maximizing the contributions from both the lattice and the magnetic degree of freedom while simultaneously minimizing the thermomagnetic hysteresis loss. An analogy is also drawn with the first order phase transition observed in dielectric materials and vortex matter of type-II superconductors. © 2013 IOP Publishing Ltd.
Jayabalan J.,Raja Ramanna Center for Advanced Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2011
The higher-order nonlinear optical response of a composite medium having metal nanoparticles is usually attributed to that originating from the third-order nonlinearity of the metal. In this article, the time dependence of hot-electron contribution to the third-, fifth-, and seventh-order nonlinear absorption coefficients of the composite medium has been studied. By comparing the results of the calculation with that of the experiments, it has been shown that the higher-order nonlinearities originating from the hot electrons of metal do contribute to the measured higher-order nonlinear absorption coefficients of the composite material. © 2011 Optical Society of America.
Roy S.B.,Raja Ramanna Center for Advanced Technology
Handbook of Magnetic Materials | Year: 2014
The magnetic field-induced temperature variation in a magnetic solid is known as "magnetocaloric effect" (MCE). A magnetic refrigerator can be envisioned using a magnetic solid, which heats up when magnetized and cools down when demagnetized. Such magnetic cooling has a potential to reduce global energy consumption and minimize the need of ozone-depleting greenhouse chemicals. There have been significant developments in the areas of magnetocaloric materials in recent times, which present an optimistic picture towards realization of both room-temperature refrigeration and hydrogen liquefaction. These developments mainly involve magnetic materials where a large MCE has been observed, which is associated with a first-order magnetostructural phase transition. This chapter provides a review of various magnetocaloric materials, which have mainly evolved during the last 20 years. © 2014 Elsevier B.V.
Singh M.K.,Raja Ramanna Center for Advanced Technology
Journal of Crystal Growth | Year: 2014
The accurate calculation of lattice energy and structure of molecular crystals represent a test of the ability of first-principles periodic density functional method to model the relatively weak intermolecular interactions found in molecular crystals. The weak intermolecular dispersion interactions need to be considered for the accurate prediction of crystal structure and lattice energy of molecular crystals. In this paper, we report the calculation of lattice energies and structure of a set of eight molecular crystals at the ab initio level of theory. Hartree-Fock and density functional theory with and without dispersion correction potential were employed. Our results clearly show with application of triple zeta polarization (TZP) basis set, the lattice parameters obtained using B3LYP functional with dispersion interactions give better agreement with the experimental results. On the other hand, the lattice energies obtained using B3LYP-D/TZP method is severely underestimated. The lattice energies calculated at B3LYP-D/6-31G(d,p) level of theory are in close agreement with the corresponding experimental results because of smaller size of basis sets provide large basis set superposition errors which compensate the missing dispersion energies. © 2014 Elsevier B.V.
Gupta P.D.,Raja Ramanna Center for Advanced Technology
Energy Procedia | Year: 2011
High power lasers are remarkable tools which can be used for a wide spectrum of material processing applications in nuclear reactors. Unique properties of lasers, like high spatial coherence and spectral purity, can be used for remote diagnostics and precision metrology. Use of optical fibers for laser beam delivery adds a new dimension to their use in rather inaccessible areas and highly radioactive environment. In this paper, a brief description of R&D work on high power solid state lasers and laserbased systems carried out at Raja Ramanna Centre for Advanced Technology, Indore, for applications in various aspects of Indian nuclear power programme is presented. © 2011 Published by Elsevier Ltd.