Department of Physics

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IIT Jodhpur

In this paper, a dielectric barrier discharge plasma based atmospheric pressure plasma jet has been generated in a floating helix and floating end ring electrode configuration using mixture of argon and nitrogen gases (50:50 ratio). This configuration is subjected to a range of supply frequencies (10-25 kHz) and supply voltages (6.5-9.5 kV) at a fixed rate of gas flow rate (i.e., 1 l/min). The electrical characterization of the plasma jet has been carried out using a high voltage probe and current transformer. The current-voltage characteristics have been analyzed, and the power consumed by the device has been estimated at different applied combinations of supply frequency and voltages for optimum power consumption and maximum jet length. A comparative analysis of the results of the above experiments has shown that maximum power consumed by the device in helix electrode configuration with end ring is 19 W for (Ar+N2) mixture as compared to only 12 mW and 7.7 mW for Ar and He gas respectively (With end ring), this may be due to the main ionization mechanisms which are different depending on the working gas. Furthermore, maximum jet length of 42 mm has been obtained for He gas at 6 kV/25 kHz due to penning ionization process in comparison to jet lengths of only 32 mm for Ar gas and jet length of only 26 mm for Ar+N2 mixture. The obtained average power consumed and maximum jet length for mixture of (Ar+N2) gases are 6.5 W and 26 mm. © 2018 EDP Sciences.

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EPJ Applied Physics

Electrical characterization of argon and nitrogen based cold plasma jet

We propose fractal information theory (FIT) to compute, and it uses a Fractal tape, wherein “every single cell of a Turing tape contains a Turing tape inside.” To use this tape, we introduce a geometric musical language (GML). This language has only one letter, a time cycle, a rhythm, a clock, or a unitary operator; on the circle perimeter, multiple singular bursts or “bings” (singularity represented as circles) are located. Time gap or “silence” between the “bings” is adjusted to hold the geometric parameters of structures such as square, triangle. Each time cycle is part of a phase space or a Bloch sphere; hence, information is now a “Bloch sphere with a clocking geometry.” Several such spheres self-assemble and expand like a balloon to store and process complex information; “bings” are singularity glue to add clocking Bloch spheres into it; this is the basic of fractal information theory (FIT). The conversion of five sensory signals into geometric shapes and rhythms like music and vice versa is called geometric musical language (GML). New information is integrated as guest into a single ever-expanding host Bloch sphere. The distinction between questions and answers disappears and replaced by “situation,” written as geometric shapes and always paired together in a time cycle, side by side or one inside another. Just like a human brain, FIT-GML hypercomputing does not require algorithm or programming, and it uses the fractal beating, i.e., geometric nesting inside a Hilbert space. FIT reduces to quantum information theory, QIT, if the clocking geometry in the Bloch sphere and virtual poles are removed and the singularity feature of a “bing” is eliminated, which makes it a classical state. © 2018, Springer Nature Singapore Pte Ltd.

Advances in Intelligent Systems and Computing

Fractal information theory (FIT)-derived geometric musical language (GML) for brain-inspired hypercomputing

In harvesting Solar Energy via, solar thermal power, design of optical field layout is one of the important parameter for efficient land usage and also optimizing the field for energy efficiency available in a given region. Thus, in concentrated solar power (CSP) we investigate a procedure for the design and optimization of heliostat field layout for a thermal power 100-150 kW having 5-7 operational hours. First, in the design of heliostat for a given power requirement, we propose the position of the heliostat, along with curvature and dimension of the heliostat. Second, for the optimal layout, shadow lengths, altitude, and azimuthal angles were considered along with different seasons at different times with respect to Jodhpur location latitude and longitude angles. The position of the heliostat were considered, which gives minimum cosine losses. The total number of heliostat considered were ranging from 50 to 60, having varying curvature depending on its distance from the receiver, were used in the layout design. Each mirror having 6.25 m(2) area and are approximately arranged in the field of 0.57 acres area of land. The field layouts are discussed in details in terms of blocking and shadowing effects. Finally, a proposed layout is discussed for the application of CSP.

Design of Field Layout for Central Receiver System to Generate 100-150 kW Solar Thermal Power

The effect of minor Al addition on structural, crystallization, soft magnetic behaviour and magnetic field induced anisotropy through DC Joule annealing in (Fe53.95Co29.05)83Si1.3B11.7-xNb3Cu1Alx, (X = 0, 1) alloys has been studied. The Al added as-quenched melt spun ribbons show good glass forming ability, better thermo-physical properties like a high Tx1 of 438 °C, Tcam of 435 °C and Tcnc of 906 °C, compared to Tx1 of 389 °C, Tcam of 409 °C and Tcnc of 900 °C for the alloy without Al addition. The longitudinal magnetic field annealed Al added alloy exhibits low Hc of 12.92 A/m and maximum Ms. of 1.78 T. The better soft magnetic properties of Al added alloy are achieved through a high nucleation density of BCC-FeCo(Al) nanocrystallites having low K1 and λ values. The as-quenched alloys possess high magneto-strain exceeding 30 ppm and approach near zero value on nanocrystallization. The longitudinal magnetic field assisted DC Joule annealing, having current density (J) in the range of J = 20–25 A/mm2 promotes good magnetic softening due to precipitation of 5–35 nm nanocrystallites as explained by extended-random anisotropy model. The Al added alloy shows better magnetic field induced anisotropy (Ku) on nanocrystallization and shows visible change in the shape of hysteresis loop. © 2017 Elsevier B.V.

Journal of Magnetism and Magnetic Materials

Influence of Al addition on structural, crystallization and soft magnetic properties of DC Joule annealed FeCo based nanocrystalline alloys

Coexistence and interplay between mesoscopic light dynamics with singular optics in spatially disordered waveguide lattices are reported. Two CW light beams of a 1.55 μm operating wavelength are launched as inputs to 1D waveguide lattices with controllable weak disorder in a complex refractive index profile. Direct observation of phase singularities in the speckle pattern along the length is numerically demonstrated. Quantitative analysis of the onset of such singular behavior and diffusive wave propagation is analyzed for the first time, to the best of our knowledge. © 2018 Optical Society of America

Fulltext

Applied Optics

Signature of phase singularities in diffusive regimes in disordered waveguide lattices: interplay and qualitative analysis

Since the discovery of graphene many studies focused on its functionalization by different methods. These strategies aim to find new pathways to overcome the main drawback of graphene, a missing band-gap, which strongly reduces its potential applications, particularly in the domain of nanoelectronics, despite its huge and unequaled charge carrier mobility. The necessity to contact this material with a metal has motivated a lot of studies of metal/graphene interactions and has led to the discovery of the intercalation process very early in the history of graphene. Intercalation, where the deposited atoms do not stay at the graphene surface but intercalate between the top layer and the substrate, may happen at room temperature or be induced by annealing, depending of the chemical nature of the metal. This kind of mechanism was already well-known in the earlier Graphite Intercalation Compounds (GICs), particularly famous for one current application, the Lithium-ion Battery, which is simply an application based on the intercalation of Lithium atoms between two sheets of graphene in a graphite anode. Among numerous discoveries the GICs community also found a way to obtain graphite with superconducting properties by using intercalated alkali metals. Graphene is now a playground to “revisit” and understand all these mechanisms and to discover possible new properties of graphene induced by intercalation. For example, the intercalation process may be used to decouple the graphene layer from its substrate, to change its doping level or even, in a more general way, to modify its electronic band structure and the nature of its Dirac fermions. In this paper we will focus on the functionalization of graphene by using intercalation of metal atoms but also of molecules. We will give an overview of the induced modifications of the electronic band structure possibly leading to spin-orbit coupling, superconductivity, …We will see how this concept of functionalization is also now used in the framework of other 2D materials beyond graphene and of van der Waals heterostructures based on these materials. © 2018 Elsevier Ltd

Progress in Surface Science

Functionalization of 2D materials by intercalation

We obtained highly n-type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in ultrahigh vacuum. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 1015cm-2. In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and the monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n-doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and x-ray photoelectron spectroscopy measurements. The band structure of this highly n-doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac cone), which has been associated with an electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals. © 2018 American Physical Society.

Physical Review B

Highly n-doped graphene generated through intercalated terbium atoms

The concentrated solar thermal technologies (CST) are versatile in view of their multi-faceted applications, such as, process heat, cooling, and electricity generation. These are of line and point-focusing types with the later having much higher flux concentration (in Suns). This allows achieving a temperature in excess of 1200 K using, for instance, the open volumetric air receiver (OVAR). Such a high temperature is useful for applications, like the one which is developed at IIT Jodhpur, namely the solar convective furnace for heat treatment of aluminum. This requires a temperature of up to 750 K in the first phase of development. Thus, a suitable solar selective coating withstanding such a high temperature and having a thermal conductivity close to the base material for operating in an open atmosphere is desirable. Because of its atmospheric exposure, air and dust-induced degradation is inevitable, which may lead to its failure. These challenges are to be addressed for adapting such high-temperature CST technologies in arid deserts of India, the Middle-East, and Africa. In view of such challenges, the following details and foreseen developments are discussed in the paper: (a)design of OVAR including various sub-components;(b)flow-stability and the effect of heat-flux distribution on an absorber pore;(c)the developed coating and its characterization for OVAR. © 2018, Springer Nature Singapore Pte Ltd.

Energy, Environment, and Sustainability

Thermal and Materials Perspective on the Design of Open Volumetric Air Receiver for Process Heat Applications

Quantum key distribution is an effective encryption technique which can be used to perform secure quantum communication between satellite and ground stations. Quantum cryptography enhances security in various networks such as optical fibers and wireless networks. In addition to this, these networks become vulnerable in presence of high attenuation due to atmospheric effects and noise. Hence, errors occurs due to decoherence. The noisy quantum channel is modeled and implemented by the redundancy-free quantum error correction scheme which provides better security and throughput efficiency as shown in simulation results. © 2018 IEEE.

2018 9th International Conference on Computing, Communication and Networking Technologies, ICCCNT 2018

Analysis of Quantum Key Distribution Based Satellite Communication

The possibility of observing nonclassical features in a physical system comprised of a cavity with two ensembles of two-level atoms has been investigated by considering different configurations of the ensembles with respect to the node and antinode of the cavity field under the framework of open quantum systems. The study reveals the strong presence of nonclassical characters in the physical system by establishing the existence of many facets of nonclassicality, such as the sub-Poissonian boson statistics and squeezing in single modes, intermodal squeezing, intermodal entanglement, antibunching, and steering. The effect of a number of parameters, characterizing the physical system, on the different aspects of nonclassicality is also investigated. Specifically, it is observed that the depth of the nonclassicality witnessing parameters can be enhanced by externally driving one of the ensembles with an optical field. The work is done in the presence of open system effects, in particular, use is made of Langevin equations along with a suitable perturbative technique. © 2018 American Physical Society.