Research Areas

Astronomy and Astrophysics

Astronomy has, since times immemorial, fascinated the human mind; observing the passage of time, diurnal motion of the celestial objects, motion of planets, and even transient phenomena such as the occurrence of eclipses, appearances of comets and supernovae explosions. The zeal to understand the celestial events combined with the terrestrial natural phenomena lead to the development of scientific principles, mathematical machinery, and engineering constructs. Astronomy and Astrophysics, therefore, relies on and feeds back into almost all fields of science, engineering and mathematics in widening our knowledge of the Universe to its very edges. We have now entered an era of multi-messenger Astronomy and can now ascertain the physics not just from the data received in the electromagnetic spectrum from radio, sub-mm, micro, IR, Optical, UV, X-rays to gamma rays, but also gravitational waves. This has greatly widened our understanding of the cosmos from black holes to the very early beginnings of the universe. We still have a multitude of unanswered questions and our faculty at IIT Delhi look into some of them listed below.

Quantum Effects in Gravity

The simplest theory of gravity, General Relativity, has passed several tests in the weak gravity regime of our solar system, to the strong gravity regions of black holes and neutron stars. However, its premise is still based on classical principles while the matter world which sources gravity is understood to work according to the quantum principles at least up to TeV scales. We do not have any successful theory of quantum gravity which combines the two sides. A semiclassical approach is therefore used when quantum and classical degrees of freedom interact with each other. This methodology has predicted several new phenomena in quantum electrodynamics as well as quantum fields in curved spacetimes such as the Schwinger effect, Fulling-Davies-Unruh effect, Casimir effect, the Hawking evaporation of Black Holes, and also forms the backbone of the inflationary paradigm of the early Universe. We at IIT Delhi seek to understand how these effects and related phenomena can be observed directly, or through analogue counterparts in the condensed matter systems. We are also probing ways to design experiments to test the quantum nature of systems based on quantum entanglement and other criteria in the domain of gravitational quantum mechanics.

Quantum-to-Classical Transition

While the fundamental nature of matter seems to be quantum mechanical, what we perceive around us is a classical reality. Even in the early Universe, as per the inflationary paradigm, the structures were seeded as quantum mechanical fluctuations. How does classicality emerge? Does it have to be with gravity? The quantum-to-classical transition and decoherence of quantum matter is an open problem that is being tackled by researchers at IIT Delhi.

Astrophysical Magnetic Fields

Magnetic fields are ubiquitous in the universe, starting from planetary scales, to the solar or stellar magnetic fields, to those in galaxies, clusters of galaxies, and finally the large-scale cosmic magnetic fields. The origin, sustenance and evolution of these magnetic fields are topics of ongoing research. Probing these magnetic fields in astrophysical systems is another task. Since the intergalactic regions and interstellar regions are composed of plasma, these lead to Faraday rotation of the polarized light forming one probe of the magnetic fields in the intervening regions. The researchers at IIT Delhi are involved in using the radio and optical data to ascertain the structure and morphology of the magnetic fields in the galaxies at high redshifts using quasar rotation measures and in our own galaxy the Milky Way using the pulsar rotation measures.

Solar Corona: Imaging, Analysis, and its Magnetic Structure

The solar corona that forms the Sun's outer atmosphere is a hot plasma that extends millions of kilometers out into space. This region is a million times dimmer than the solar surface beneath, yet, strangely, it’s at least 1 million kelvin hotter. Seven decades after the unexpected observation was first made, it’s still one of the biggest mysteries in astronomy. Being logarithmically faint, the corona is visible only during the Total Solar Eclipses (TSE) when the photosphere is obstructed by the moon during the duration of the totality or through specially designed coronagraphs. There are actually three types: K, F and E - coronas based on the different properties. It is widely thought the Sun’s magnetic field structure shapes its outer atmosphere, and thus we look into the Magnetohydrodynamic simulations to ascertain the solar activity and the physics. We are involved in obtaining the data of the Solar Corona during the TSE, its processing, analysis and ascertaining the magnetic field structure from ground up.

Faculty Associated : Suprit Singh

Computational and Statistical Physics

We work in the area of Statistical and Computational Physics which is devoted to understanding macroscopic assemblies of identical particles. Since such systems abound in nature, the scope of the subject is vast. We have studied diverse systems, many within the realm of condensed matter physics, some at the interface of statistical physics and bio-medicine and some at the interface of statistical physics and optics. Our recent research problems are on complex spin systems (dipolar magnets, spin glasses and quantum glasses), complex fluids (liquid crystals with nano-inclusion) and emergent properties of magnetic nanoparticle assemblies. We use analytical techniques from equilibrium and non-equilibrium statistical physics along with computational techniques such as Monte Carlo, parallel tempering, molecular dynamics, graph cuts, etc. Many of these studies are strongly driven by experiments which have reinforced and complemented our theoretical formulations.

Faculty associated: Varsha Banerjee

Miniature heat engines generally referred to as micro-engines constitute a fascinating field of current research. These engines consist of a single or a few microscopic particles or spins (called as a working substance), and are driven by an external time dependent force. Hence, taking the system out of equilibrium. Due to the smallness of the system, fluctuations dominate over the mean values of the thermodynamic quantities like work, heat, entropy etc. For such inherently non-equilibrium systems, average values of the thermodynamic quantities are insufficient and full probability distributions need to be studied. Due to a very noisy environment micro-engines perform poorly in terms of efficiency, reliability when compared with thermodynamic engines like Carnot, Stirling Engines. My group at IIT, Delhi tries to understand such micro engines with newly developed technique of "Stochastic Thermodynamics". We are also extending these studies to active particle systems e.g. bacteria. We are also studying Quantum Particle and Heat Transport in mesoscopic systems.

Faculty associated: Rahul Marathe

Understanding the swimming of micro-organism in complex environment is very important for a variety of medical applications. We try to model both natural as well as artificial swimmer in Newtonian as well as non-Newtonian fluids. One area of focus is how micro-organism adopt different strategies to survive in harsh environment they live. Another area of particular interest is to model protein aggregation using patchy colloidal particles. Here we focus on the bundle formation of amyloid fiber responsible for many neuro degenerative diseases. The isotropic as well as anisotropic particles aggregation and dynamics are studied using the tools of equilibrium and non-equilibrium statistical mechanics.

Faculty associated: Sujin B Babu

Condensed Matter Experiment

The research activity of condensed matter experiment (CME) group at the Physics department of IIT Delhi covers a wide range of topics such as (i) nanostructured materials, thin films and devices, (ii) novel magnetic multifunctional and topological materials, (iii) spintronics and magnetism, and (iv) optical properties of condensed matter e.g., ultrafast dynamics of condensed matter with femtosecond laser. CME group houses several specialized experimental laboratories as well as several departmental facilities. The CME group has close links with Nanoscale research facilities of the institute that houses a clean room as well as several characterization facilities. At present, the department has a X-Ray diffractometer, a X-ray photoelectron spectroscopy, a SQUID magnetometry, a physical property measurement system, ultrafast-optics laboratory (also housing a Raman spectrometer and a photoluminescence set-up), a pulse laser deposition system, and an atomic force microscope as departmental facilities. Individual research labs also have several state-of-art facilities, the details of which can be found by visiting the corresponding laboratory web pages.

Nanostructured Materials, Thin Films, and Devices

We also focus on following activities. 2D materials, 2D-3D interfaces and devices for thermoelectric, photovoltaic, LEDs, photo-electrochemical and gas sensor applications. Growth of metal, semiconductor, hybrid, alloy and core-shell nanoparticles and nanostructure/nano- composites for specialized applications such as water splitting for hydrogen production, nanogenerator for harnessing mechanical energy, thermoelectric devices, solar cells, microwave tunable filters, resistive switching memories. Physical properties of complex oxide heterostructures at nanoscale for energy storage applications and electron-correlated materials, study of condensed matter using scanning kelvin probe, SQUID, conducting atomic force and thermal microscopy, conventional absorption and PL spectroscopy, and advanced spectroscopies such as surface enhanced Raman spectroscopy (SERS), CARS etc.

Faculty associated: B. R. Mehta, Neeraj Khare, P. Srivastava, Santanu Ghosh, R. S. Dhaka, J.P. Singh, R. Singh, M. C. Bhatnagar, and G. Vijaya Prakash

Novel Magnetic Multifunctional Materials

We focus on “Smart magnetic multifunctional materials” such as (i) Magnetic Shape Memory Alloys, (ii) Multiferroic materials with magnetoelectric coupling, (iii) Topological insulators, (iv) Multifunctional Huesler alloys for spintronics, (v) non-linear antiferromagnets for spin-orbit torque.

Faculty associated: R. Chatterjee, S. Chaudhary, P. K. Muduli, Neeraj Khare, Santanu Ghosh, R. S. Dhaka

Spintronics and Magnetism

We focus on emerging areas such as the spin Hall effect and its inverse, spin-orbit torques, magnetic skyrmions, spintronic based THz emitters, and 2D-spintronics. Magnetoresistive Tunnel Junctions (MTJ) for ultrahigh sensitive magnetic field sensors, microwave oscillators and next generation Magnetic Random Access Memories (MRAMs), Transparent Ferromagnetic Semiconducting (FMS) oxides for semiconductor spintronics, growth and characterization of epitaxial half-metallic (100% spin polarized) ferromagnetic thin films, fabrication of spin ice structures, magnetism in bulk and thin Films of metallic ferromagnets, Heusler alloys, superconducting oxides and other oxides.

Faculty associated: R. Chatterjee, S. Chaudhary, P. K. Muduli, Santanu Ghosh, P. Das, S. Manna, R. S. Dhaka

Optics of Condensed Matter

Our research interest is in the interdisciplinary areas of condensed matter physics and photonics using continuous wave (CW) as well as ultrafast femtosecond(fs) lasers to study a variety of condensed matter systems. The THz research activities are broadly based on: (a) investigating the ultrafast carrier dynamics of different materials using ultrafast UV pump – THz probe studies, (b) studying the effect of extreme P-T conditions to provide a new route toward discovering advanced structural materials and new materials with enhanced performance for energy transformation, and (c) understanding the large-scale behavior of the Earth and other planets through experimental study of geological materials and minerals under extreme P-T conditions.

Faculty associated: S. Kumar, G. Vijaya Prakash, A. Sengupta

Condensed Matter Theory

Computational Materials Modelling

We work in interdisciplinary areas of condensed matter physics with broad research interest in first principles based simulation of designing new materials and understanding their properties using state-of-the-art density functional theory (DFT) and beyond methods. We predict properties of materials by integrating different level of theories and validate our prediction using the highest level of theoretical approaches within the DFT framework or by comparing with experimental data (if available). Most of the materials we design have significant impact in materials science. In addition, we aim at developing theoretical methods that allow us in understanding general rules of a given problem in materials science. We solve the problem by including electronic correlation effects by combining DFT with quantum chemistry methods (eg. HF, MP2, CCSD) and their applications to solve multiscale and multidisciplinary research problems. In order to capture the effect at finite temperature and pressure to mimic real experimental environment, we employ the ab initio atomistic thermodynamics and beyond approaches.

Faculty associated: Saswata Bhattacharya

Atomic and Many-atom Complex systems

We develop and use the computational tools to probe the fundamental physics and related technological applications for atomic and many-atomic complex systems. For single atom or ion, we develop Relativistic Coupled-Cluster based theories and sophisticated codes and probe various fundamental physics such as atomic clocks, parity and time-reversal violations, anopole moment, and the search for the variation in the fundamental constants. For condensed matter systems, we develop the first-principles based atomistic models to simulate the properties at finite temperatures. For properties at zero Kelvin we use Density Functional Theory and based methods. Some properties of our interest include electronic and band structure, dielectric, pyroelectric, piezoelectric, flexoelectric, caloric, magnetization and magnetic properties, phonons, magnons and electromagnons in complex (anti)ferroic oxides bulk and nanostructures.

Faculty associated: Brajesh Mani

Light-Matter Interaction in $sp2$ Carbons

Here we delve the interaction of light with nanoscale aggregations of graphitic ($sp^2$-hybridized) carbons such as single, multi-layer, dot-like and twisted graphenes, and pristine and functionalized carbon nanotubes (CNTs) using a combination of many-body theory and high-precision computational (ab initio, and numerical) modelling techniques for investigating their electronic and vibrational properties and optical response. Currently, we're interested in elucidating and finding experimental signatures for higher spectroscopies such as second-order Raman scattering in the framework of exciton-polariton scattering which results in lower-dimensional carbons due to the diminished screening between their charge carriers. We're also exploring the possibility of indirect-exciton formation in twisted bilayer graphene which is particularly exciting given the strong possibility of prominent electron corrections effects at magic angles. Using ab initio calculation we're also exploring the viability and rational design of real-world functionalized CNT metastable photoswitches and single-photon emitters (SPEs).

Faculty associated: Rohit Narula, Sankalpa Ghosh

High Energy Physics

Every day we encounter hundreds of matters and forces (e.g., electrical, mechanical, gravitational, etc.) around us. The diversity of matters and forces raises two rational questions: (1) What are the matters composed of? and (2) Are these forces all distinct or somehow connected? High Energy Physics (HEP) aims to answer these questions: it probes the most elementary units of matter and investigates fundamental interactions among those basic constituents. The foundation of HEP, which attempts to address the aforesaid queries, is known as the Standard Model (SM) of particle physics. The SM houses only elementary entities like leptons, quarks, photons, W & Z bosons, gluons and the Higgs boson. Some of these (leptons, quarks) act as the foundation of all matters, some others are (photon, W & Z bosons, gluons) responsible for mediating fundamental (electromagnetic, weak and strong, respectively) interactions while the Higgs boson appears instrumental for mass generation. The success of SM in understanding mother nature is truly magnificent and it has already bagged more than twenty Nobel prizes.

The stupendous success of the SM is, however, not impeccable. There exist theoretical glitches (e.g., hierarchy problems, unification of all fundamental interactions including gravity, etc.) as well as experimental anomalies (e.g. non-zero neutrino masses and mixing, hints of dark matter from galaxy rotation curve, matter-antimatter asymmetry of the Universe, etc.) that demands physics beyond the SM to reveal the mysteries of our Universe.

The High Energy Physics group of IIT Delhi comprises the following faculty, actively involved in a wide variety of research areas:

  1. Prof. Amruta Mishra: Physics of strongly interacting matter.
  2. Prof. Pradipta Ghosh: Beyond Standard Model phenomenology: Supersymmetric Models, R-parity violation, Neutrino physics, Electroweak Phase Transition and Gravitational Waves, Collider, Dark Matter, Charged Lepton Flavour Violation
  3. Prof. Tobias Toll: Strong force phenomenology and Monte Caro Event Generators.
  4. Prof. Suprit Singh: Quantum Fields in Curved Spacetimes, Quantum-to-Classical Transition and Decoherence and Gravitational Quantum Mechanics.
  5. Prof. Tarun Sharma: Chern Simons theories & Anyonic statistics, AdS-CFT, Higher Spin gauge theories, Fluid dynamics & gravity, Supersymmetry, String theory.
  6. Prof. Abhishek M. Iyer: QCD/Composite dynamics, Physics of Kaons and ML for particle physics and beyond.
  7. Prof. Sarthak Parikh: Theoretical and Mathematical High Energy Physics: Gauge/Gravity Duality (AdS/CFT correspondence), Conformal Field Theories, Quantum Gravity, Discrete Models of Spacetime, Quantum Computation and Quantum Information Theory.

Physics of strongly interacting matter (a group of two PhD scholars led by Prof. Amruta Mishra)

Optics and Photonics

Research at the optics and photonics division of department of physics covers a wide range of topics, including nonlinear optics, quantum optics, nanophotonics, ultrafast optics, quantum technologies, biophotonics, singular optics, integrated optics, spectroscopy, optical fibre communication, holography, imaging, microscopy.and computational optics. The research activities are summarized under the following thematic areas of research:

Physics of Quantum Matter and Information systems

Ion-atom collision physics

My area of interest is collision of highly charged ions interaction with atoms, molecule of biological interest, clusters and ices of bio-and astrophysical relevance. My work involves low and high energy accelerators (keV/u – MeV/u energies). The collisions products, ions/electrons/ radicals are analysed with several techniques including Time-of-flight, electron spectrometers and Cold Target Recoil Ion Momentum Spectrometers (COLTRIMS). These studies are of great interest for the bio-medical application to estimate the damages to the human DNA/ RNA caused by exposure to ionizing radiation. Also, the experiments can simulate the astronomical phenomena such as evolution of larger molecules by irradiation of small molecules by cosmic rays.

Faculty associated: Aditya Narain Agnihotri

Cold atom quantum technology

The beauty of cold atom based quantum technologies is that, one can design versatile quantum systems and fully control their properties by simple and clever approaches, just because of the inherent quantum nature of atoms and photons. In one approach we cool atoms to million times colder than room temperature using precisely frequency tuned lasers. In a second approach we trap these cold atoms in optical potentials even to the single particle level. With these abilities, we can design textbook like quantum systems with few individually addressable atoms. The real world problems demand to build large quantum systems beyond textbook examples. The biggest challenge in achieving this goal is to know how to control the environment induced decoherence. In our research group we aim to address these open problems in a step by step manner. These technological and conceptual developments will lead us to build large scale quantum information processing network, quantum computation protocols for solving industry and society relevant problems, quantum sensing devices and quantum metrology modules for precision instrumentations and measurements.

Faculty associated: Bodhaditya Santra

Magnetics & Advanced Ceramics Lab

Our group works on topological classification of semi-metals using experimental and DFT simulations. Topological semi-metals are classified as a quantum phase of matter that host Dirac and Weyl fermions. The researchers working in the area of quantum matter physics, study the transport properties of these exotic materials under very low temperature, high magnetic field and high pressures. Our group has worked on Bi Selenide / Telluride single crystal Topological Insulator (TI) and have demonstrated 3D TI behavior in these crystals. Presently we are working on rare earth based Half Heusler (HH) alloy systems for their non-trivial surface states. The general formula of these XYZ HH alloy systems, where X can be any rare earth element like Dy, Er, Yttrium etc., Y is generally transition element Pd, Pt, Au and Z is usually heavy element proving SOC like. Bi, Sb, etc.; show interesting surface state properties.

Faculty associated: Ratnamala Chatterjee


Plasma Physics

Plasmas are known to be the fourth state of matter which is formed when one or more electrons of a large fraction of the constituent atoms of a gas are removed by supplying them energy larger than their ionization energy. However, not all the atoms are in ionized state and therefore a plasma basically comprises of three kinds of species, namely electrons, ions and neutrals. They are known to constitute more than 99% of the visible matter in our universe and therefore attract a wide research interest.

In the plasma physics division of our department, we are primarily working in the broad research areas of high intensity laser-plasma interactions, plasma-material interaction and dusty plasmas. Areas of particular research interest are laser-plasma based charged particle acceleration, fast ignition, relativistic electron beam propagation, magnetic field generation, x-ray laser excited nanoplasmas, terahertz (THz) radiation generation, nonlinear waves including solitons, Hall thrusters, particle acceleration and density modulation by microwaves, plasma / surface nitriding, visco-elastic effects in dusty plasmas, and turbulence in laboratory and astrophysical plasmas. We employ theoretical as well as numerical methods, namely, hydrodynamics, molecular dynamics and particle-in-cell (PIC) techniques to investigate some of the key questions in the above areas and also perform experiments in some of the areas.

Laser-plasma based charged particle acceleration

Plasmas can support very high electric fields, several orders of magnitude larger than those supported by the modern RF accelerators, owing to the fact that they are already broken down unlike materials which can sustain electric fields below a value for which field ionization becomes prominent. This makes plasmas ideal candidates for charged particle acceleration in relatively shorter distances (~ few meters as a whole system) as compared to several kilometers large RF accelerators currently under operation, e.g., LHC@CERN. Both electrons as well as ions can be accelerated using schemes involving high intensity lasers interacting with plasmas. Techniques to improve the beam quality (monoenergeticity and reduced spread) and to increase the beam current are some areas of active research interest. We employ theoretical models as well as some massively parallel PIC codes for investigating current issues related to the laser-plasma based ion acceleration schemes, namely, target normal sheath acceleration and radiation pressure acceleration.

Faculty associated: H.K. Malik, A. Das, V. Saxena

Modeling of laboratory plasmas

We are also interested in modeling laboratory experiments pertaining to electron cyclotron resonance based large volume uniform plasma production with potential applications in generating negative hydrogen ion beams for fusion applications as well as in efficient electrodeless plasma thruster applications. For these studies, we closely collaborate with the Plasma Physics Lab (PPL) of Centre for Energy Studies (CES), IIT Delhi, where these experiments are being carried out.

Faculty associated: A. Das, V. Saxena

Visco-elastic effects in dusty plasmas

A dusty plasma comprises of electrons, ions, neutrals and micron sized dust particles with very high negative charge. As for such plasmas, the electrostatic interaction is very strong, they are also termed as strongly coupled plasmas. Owing to this strong coupling effect these plasmas exhibit some solid like properties (e.g., elasticity) along with some fluid like characteristics (e.g., viscosity). These visco-elastic properties can be tuned by varying the strength of coupling which is mainly controlled by the background plasma parameters. In this context, different coupling regimes are investigated using generalized hydrodynamics as well as classical molecular-dynamics simulations.

Faculty associated: A. Das

X-ray laser excited nanoplasmas

Modern day x-ray sources boast of sub-angstrom wavelengths and ultra-short pulses with decent brightness. These x-ray sources are ideal candidates for imaging complex bio-molecules. However, to understand the physics involved, rare gas clusters are the perfect test beds as they can be easily prepared in varied sizes. Therefore, it is important to first understand the two phases of the nonlinear interactions of intense x-ray free electron laser pulses with these clusters: the first phase involving x-ray irradiation of the rare gas clusters dominated by photo processes, and the second phase of nanoplasma expansion dominated by collisional hydrodynamics. We model this whole process by a computationally efficient two stage semi-classical molecular dynamics – hydrodynamics scheme.

Faculty associated: V. Saxena

Terahertz (THz) radiation generation

We have suggested different methods for the efficient THz radiation generation through the interaction of laser with plasma, gas jet and nanostructures. A concept of efficient tunnel ionization has been established by employing the superposed field of two lasers in addition to the analytical calculations for the frequency of emitted radiation. Means have been discussed for the stronger and collimated radiation. On the other side, the role of laser pulse shape has been uncovered in getting stronger ponderomotive force for the generation of stronger current in the laser beating process. The use of external magnetic field for tuning the frequency, power, focus and polarization of the emitted radiation has been discussed in greater detail. Other concerns have been to achieve multifocal THz radiation for its medical applications and now our focus is to generate the THz radiation suitable for its spectroscopic applications.

Faculty associated: H.K. Malik

Instabilities and electron transport in Hall thrusters:

Hall thrusters are the space propulsion devices where Xe plasma is created and ions are accelerated to provide thrust to the device. However, owing to the gradient in density and magnetic field, and resistive coupling of oscillations with the electrons drift lead to various kinds of instabilities. We have focused on Rayleigh-Taylor (RT) instabilities and resistive instabilities. For the first time we showed analytically that there is a frequency band for the occurrence of RT instability. Also means to suppress these instabilities were discussed. Work is underway to find an appropriate profile of magnetic field for the suppression of such instabilities, in addition to both the electrostatic and electromagnetic resistive instabilities. The role of finite temperature of the ions is being talked about in this direction. The recent problems of dust generation due to the collisions of ions with the walls and the shut down of these devices are being addressed. The field of the instabilities is thought to be used for the electron transport and efficient plasma generation for increasing the efficiency of these devices. Also we are working toward designing of an efficient Hall thruster.

Faculty associated: H.K. Malik

Plasma-material interaction

Nitriding is an advanced future technology concerning the realization of improvement in mechanical and electrical properties simultaneously. In order to attain the suitability of the materials, low carbon steels and titanium fit very well for proper industrial and electronic device applications. However, there are several issues that need to be discussed before implementation of the materials. We aimed to improve the mechanical hardness by employing different approaches, viz. hot cathode arc discharge plasma and low energy ion beam implantation, and controlling the growth parameters. For this a hot cathode arc discharge plasma system has been developed for plasma nitriding where both the plasma and nitriding parameters could be controlled separately. We focused on low carbon steel and titanium for the hardness since the titanium is also recognized for its strategic importance as a unique light weight, high strength alloy, structurally efficient metal for critical, high-performance aircraft, such as jet engine and airframe components. Based on our experimental study with plasma nitriding and ion implantation for hardening of steel and titanium samples, it is easy to optimize the plasma parameters for achieving desired mechanical properties in these samples for their specific applications. In the above phenomenon, sheath plays a vital role which is responsible for modifications of surface and tribological properties of materials under investigation. The sheath formed in electronegative plasmas is designated as an electronegative sheath which has an immense application in various fields like thin films depositions, plasma chemistry, plasma-surface interactions, semiconductor industries, microelectronics industries, spacecraft propulsion and many more. The interaction of electronegative discharges with an absorbing surrounding plasma wall is an important problem for many applications, such as material processing, Langmuir probe diagnostics, and plasma sheath lenses. Hence, our focus is now on developing theoretical models to make an in depth study of the sheath formation and behaviour of plasma parameters in electronegative plasmas under the effect of an oblique and constant magnetic field, presence of collisions and charged species’ distinctive temperature, etc. Also experimental study on ion sheath formation and its modification due to different plasma parameters like dose, implantation time, the multiplicity of ions, etc. are underway for achieving desired properties of materials. During the nitriding process, change in temperature leads to the formation of different microstructure at the surface of the investigated material. So modifications of microhardness, corrosion resistance, etc. are also our objectives. In this direction, we are looking for a mechanism that enables us to control the electronegativity and temperature of negative ions through the energy exchange of microwave with the plasma electrons and their collisions with the negative ions. In collaboration with SSPL we are also working on plasma based passivation study for AlGaN/GaN using plasma enhanced chemical vapor deposition (PECVD) and inductively coupled plasma chemical vapor deposition (ICPCVD) techniques. Theoretical modelling is now being done for such systems used for plasma etching where dust contamination is the important ingredient.

Faculty associated: H.K. Malik

High energy particle beam interaction with materials

The physical properties of the materials are not only sensitive to the beam species, energy and their fluences, but also to the other beam parameters such as beam profiles, effective beam cross sections and emittances, during ion beam irradiation or implantations on the materials. We have uncovered the role of beam profiles and effective cross section of ion beam during ion-matter interactions in tailoring the physical properties of nanostructure materials during implantations of two kinds of beam species, C and N ion beams, in the ZnO thin films prepared by RF sputtering. It was revealed that the ferromagnetism, bandgap energy, grain size, crystallinity, electrical and many other structural, morphological, compositional and optical properties can be engineered and tuned by varying the ion beam profiles and effective beam cross sections of the incident ion beam and keeping other beam parameters like beam current, energy and fluence constant. Now we are focusing on the mechanism taking place during the high energy ions and materials interaction. Such mechanism need to be explored in detail in order for better understanding and observation of radiations produced. The tuning of emitted radiation is also an important ingredient of our study.

Faculty associated: H.K. Malik

Microwave plasma interaction

We proposed to employ special kinds of microwave pulses for particle acceleration in plasma filled waveguide and also creating density gradient in plasma in particular direction. We have suggested important methods to divert and collect the accelerated particles from the waveguide. Based on the proposal, the cost of the particle accelerator can be brought down compared to the laser based accelerator systems. The microwaves are now being employed for the density modification which could be used for the resonant excitation and tuning of THz radiation and on the other side in fusion related aspects. Experimental studies related to controlling the density gradient in plasma by microwaves are also underway.

Faculty associated: H.K. Malik

Propagation, reflection and transmission of solitons:

We have developed theoretical models for the propagation, reflection and transmission of electrostatic solitons in different kinds of plasmas. For this, various transformations have been discovered in order to solve the relevant equations. Simulation study has been recently conducted for uncovering the role of perturbing pulse for the excitation of electromagnetic solitons and their collisions. Investigations are underway to find the conditions for total reflection keeling in mind the application of solitons in communications as well.

Faculty associated: Amita Das

Fast Ignition (FI) concept of laser Fusion

Fast Ignition (FI) concept of laser Fusion: The inertial confinement fusion scheme relies on achieving the Lawson criteria for fusion by working with a compressed high density fusion target of super-solid densities. While compression of fusion target by lasers is possible, the creation of a hot spot for ignition has simultaneously has been a problem. The fast ignition concept of laser fusion separates the task of compression and creation of a hot spot for ignition. This has several advantages as one no longer has to compress a hot fuel and nor does one have to deal with certain hydrodynamic instabilities which mix up hot and cold fluids. This is avoided in FI scheme of laser fusion where the electrons generated by a fast sub-picosecond laser pulse is utilized to create a hot ignition spot. The energetic electron transport through plasma and possible anomalous behavior of transport are crucial in this regard which are issues for investigation. One important study involved a proposal for a new mechanism of shock dissipation which was experimentally verified by groups in ILE Osaka and TIFR.

Faculty associated: H.K. Malik

Magnetic field generation and turbulence in laboratory plasmas

Issues related with magnetic field generation and their turbulence in laboratory laser plasma interaction having astrophysical implications are being studied. There are ongoing collaboration with TIFR experimental group of UPHILL laboratory.

Faculty associated: Amita Das

MS-415, 3rd floor, Department of Physics, Indian Institute of Technology Delhi, Hauz khas, New Delhi, 110 016, India