Projects reports of M Sc course http://dspace.dtu.ac.in:8080/jspui/handle/repository/18356 2026-07-02T14:26:10Z 2026-07-02T14:26:10Z SINHA, ANCHIT Sharma, Suresh C. (SUPERVISOR) http://dspace.dtu.ac.in:8080/jspui/handle/repository/22958 2026-07-02T05:24:42Z 2026-05-01T00:00:00Z

Title: ANALYSIS OF SELF-FOCUSING OF LASER BEAMS IN QUANTUM PLASMA Authors: SINHA, ANCHIT; Sharma, Suresh C. (SUPERVISOR) Abstract: The relativistic self-focusing of laser beams in quantum plasma has drawn considerable inter est because of its applications in inertial confinement fusion, charged-particle acceleration, and high-energy-density physics. In this dissertation, we study the propagation and self-focusing of non-conventional beam profiles, namely Bessel-Gaussian and Elliptical-Gaussian beams, in magnetized quantum plasmas with spatial density gradients. The paper considers combinations of beam geometry, magnetic fields and plasma inhomogeneity which have never been system atically treated in previous work. The study uses the quantum hydrodynamic (QHD) model, incorporating the Bohm potential, exchange-correlation effects, relativistic ponderomotive forces, and the influence of an exter nal magnetic field. Applying the paraxial approximation and the Wentzel–Kramers–Brillouin (WKB) method reduces Maxwell’s equations to a differential equation governing beam-width evolution along the propagation axis. For Paper-1 on Bessel-Gaussian beams, this results in a second-order nonlinear ordinary differential equation, solved numerically using the fourth-order Runge-Kutta method. Simulations are carried out for high laser frequencies of (1.78×1020s−1), electron densities of (n0 = 4 × 1019cm−3) satisfying (χ ≥ 1), an axial magnetic field of (ωc/ω = 0.3), and exponential density ramp parameters (d = 5,10,20). Key findings from Paper-1 show that: (1) thermal quantum plasma enables much stronger and more sustained self-focusing than classical and cold quantum plasmas; (2) exponential den sity ramps greatly accelerate self-focusing, maintaining high intensity over multiple Rayleigh lengths; (3) Bessel-Gaussian beams outperform Gaussian beamsbecauseoftheirring-shaped in tensity profile; (4) the transverse wave parameter µ significantly enhances self-focusing; and (5) beyond a threshold, increasing laser intensity reduces self-focusing due to relativistic mass satu ration and exchange-correlation effects introducing competingnonlinearities. Paper-2(Elliptical Gaussian beams in magnetized quantum plasma with tangential densityramps)isinanadvanced stage with mathematical framework and numerical analysis under way.

2026-05-01T00:00:00Z AMISHI Bohidar, Himadri B (SUPERVISOR) http://dspace.dtu.ac.in:8080/jspui/handle/repository/22954 2026-06-30T04:31:45Z 2026-05-01T00:00:00Z

Title: KINECTICS OF PROTEIN- AGGREGATION AND SELF ASSEMBLY Authors: AMISHI; Bohidar, Himadri B (SUPERVISOR) Abstract: The process of protein aggregation is a vital one which depends on time and necessitates models which transcend closed-system approaches to become models of dynamic kinetics and proteostasis. The generalized modelling approach connects the physical mechanism of aggregation with the biological system of aging. This physical model is composed of kinetic laws, the behaviours of the source terms (monomer generation/elimination), and thermos- reversible assembly. The model predicts the scaling behaviours of aggregation which depend on whether the process is limited by the formation of aggregates or the generation of monomers. The biological aspect of the modelling framework takes into account the effect of the decline in the process of proteostasis in a systems biology model. Coupled differential equations form the basis of this biological model with consideration of the decline in physiological function, hormone regulation, genetic instability, and gender-related effects. Importantly, the non-linear dynamics of proteostasis with respect to age-related stresses and inefficient clearing must be accounted for since they can lead to a tipping point where a rapid build-up occurs.

2026-05-01T00:00:00Z TARUNA VARSHNEY, DIVYANSH RANJAN Bokolia, Renuka (SUPERVISOR) http://dspace.dtu.ac.in:8080/jspui/handle/repository/22878 2026-06-23T05:17:04Z 2026-05-01T00:00:00Z

Title: STUDY OF ELECTRICAL PROPERTIES OF DY3+ DOPED SRBI2NB2O9 AURIVILLIUS CERAMIC FOR ELECTRONIC APPLICATIONS Authors: TARUNA; VARSHNEY, DIVYANSH RANJAN; Bokolia, Renuka (SUPERVISOR) Abstract: The effect of Dy³⁺ substitution on the structural, dielectric and ferroelectric properties of SrBi(2-x)DyxNb2O9 (SBN) (x=0.00,0.02,0.04,0.06) was systematically investigated, and the samples were synthesized using the conventional solid-state reaction method. X-ray diffraction (XRD) confirmed the formation of a single-phase orthorhombic structure, indicating successful incorporation of Dy³⁺ into the lattice. The substitution of Dy³⁺ caused systematic variations in lattice parameters and unit cell volume, suggesting localized structural distortion. Scanning electron microscopy (SEM) revealed a plate-like grain morphology with random orientation, characteristic of layered perovskite systems. FTIR spectroscopy confirms bands are present at 816 cm-1, 612 cm-1, and 454 cm-1. Dielectric studies show well-defined ferroelectric characteristics with low dielectric loss. The dielectric constant (ɛ) was observed to be 160 for undoped SBN ceramic. The Polarization-Electric field (P-E) hysteresis measurements confirmed the ferroelectric behavior of all compositions. The remanent polarization was recorded as highest at 4% (x=0.04), and 2Pr was 7.95 µC/cm2, whereas the coercive field 2Ec was 63.05 kV/cm. The variation in remanent polarization (Pr) and coercive field (Ec) with Dy³⁺ content indicates that dopant concentration significantly influences ferroelectric characteristics. Temperature-dependent PE loops indicate a stable ferroelectric response over a wide temperature range, 30°C to 180°C, with improved polarization. Good polarization retention with minute variations in remanent polarization (Pr) and coercive field (Ec) up to 10000 switching cycles, confirming good fatigue endurance and stability. Analysis of leakage current up to 10000 switching cycles reveals good insulating behaviour of the material with reduced defects and hence exhibits good electrical stability. Overall, Dy³⁺ substitution enhances structural stability, ferroelectric switching, and dielectric properties, making them useful in energy storage and sensing applications.

2026-05-01T00:00:00Z GERA, JATIN JAIN, SIDDHARTH Meena, Deshraj (SUPERVISOR) http://dspace.dtu.ac.in:8080/jspui/handle/repository/22847 2026-06-16T04:40:19Z 2026-05-01T00:00:00Z

Title: ENHANCED THERMOELECTRIC PROPERTIES OF TIN SELENIDE-BASED FLEXIBLE POLYMER COMPOSITES Authors: GERA, JATIN; JAIN, SIDDHARTH; Meena, Deshraj (SUPERVISOR) Abstract: In this study, we have investigated the thermoelectric properties of Tin Selenide (SnSe) and fabricated polymer based thin films doped with SnSe. SnSe was synthesized using the Solvothermal synthesis method. The structural properties were studied using XRD, FTIR spectroscopy and the thermoelectric properties were studied using the bridge method and the four probe method within the temperature range 270K - 420K. The mean resistance of the sample in a thin pelleted form is 1037 ± 18 Ohm. The sample was found to be thermally stable up to 1073K using TGA. The peak value of electrical conductivity was found out to be 0.115 S/cm at 352K. The Seebeck coefficient of the sample was also found out to be stable within the given temperature range with an optimized value of 0.184 mV/K with a power factor of 1.324 x 10-3 µWm-1 K-2. The thin films were synthesized using the Drop-Casting method. The structural properties were studied using XRD and FTIR and the thermoelectric properties were studied using the bridge method and the four probe method within the temperature range 270K - 420K. The results certify the capability of SnSe as a promising base material for Thermoelectric devices and the stability of the power factor over low temperature range also promises real world applications.

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