Mr. H. L. Swami, Scientific Officer–E

Fusion Reactor Design Division, Institute for Plasma Research, Gandhinagar, Gujarat

Date, time & venue: 17/10/2019, 3.00 pm, CPP-IPR Seminar Hall

Neutron source facilities are being developed for various kinds of purposes such as design mock-up experiments, medical treatment, detection of special nuclear materials, etc. The design and development of neutron source should be done by considering the human safety from associated radiation risk of neutrons exposure. The neutrons can cause a direct and indirect effect on the human. There are various risks to humans from radiation exposure like sickness, bone-marrow (hematopoietic) syndrome, gastrointestinal syndrome and fatal problems. The health issues due to the radiation depend on the radiation dose consumed by the human body. For the safe and smooth operation of a neutron source, nuclear safety evaluation is essential to avoid human health risks. The national nuclear regulatory is imposed a regulation for the radiation doses for human accessible zones of nuclear facilities. In order to protect humans from radiation exposure, the human accessible area source should be well shielded and have limited doses as per the regulatory design. The talk covers the human health risk due to radiation exposure and the regulatory dose limits for human radiation exposure. The remedies to overcome the radiation doses are included in the talk. It also gives a glimpse of the neutron shielding design of the facility and neutronics related associated work for operational clearance from regulatory.

Prof. Asoke Kumar Sen

Department of Physics, Assam University, Silchar, India

Date, time & venue: 03/05/2019, 3.00 pm, CPP-IPR Seminar Hall

Comets are being studied for last several decades using ground based telescopes , to understand their orbits, gas and dust contents and other dynamical properties. Since the comets are believed to contain the most pristine materials of our solar system out of which Sun and other planets were born some 4.6 billion years ago, the above studies help us to understand the origin and evolution of our solar system. The dust particles which are released from the comet nucleus, contain most of these pristine materials. These particles scatter the solar radiation and are responsible to give the comets a bright spectacular appearance. Such scattered radiations are studied through photometry and polarimetry by the ground based telescopes to understand the properties of cometary dust and also the scattering processes in general. In addition, in recent years a number spacecrafts had flown very close to some of the comets and made very interesting in situ measurements on cometary dusts.

These spacecraft measurements, together with the ground based observations on cometary dusts are providing us now, new insights into the processes which led to the formation of the comets and other members of the solar system.

Dr. U. N. Pal, Principal Scientist

CSIR- Central Electronics Engineering Research Institute, Pilani, Rajasthan-333031

Date, time & venue: 22/11/2018, 11:30 am, CPP-IPR Seminar Hall

Presently, there is growing concern in pulsed plasma devices and technologies, such as, high power plasma switches (Thyratron and pseudospark switch (PSS)) for different pulse modulators and high energy physics applications; high density and energetic electron beam sources for microwave and surface modification applications; Extreme Ultraviolet (EUV)/X-ray sources for surface modification of polymers, X-ray Crystal Spectroscopy (XRCS) and radiography of small objects for potential biological applications; and plasma assisted compact microwave and THz sources. Keeping in view of these applications, CSIR-CEERI has initiated the research activities on pulsed plasma devices and technologies, particularly thyratron switches and pseudospark (PS) discharge devices in early 2000. The talk has covered the recent technological efforts made by CSIR-CEERI for the design, development and characterization of high power plasma switches, such as, Thyratrons (25kV/1kA, 35kV/3kA and 40kV/3kA) and PSS (25kV/5kA, 40kV/10kA and 20kV/100kA) for different pulse power applications of strategic importance. Such plasma switches are presently being imported and have always been a subject to import restrictions, causing hurdles in Indian efforts for advancing technologies in high energy research areas. The design, fabrication, processing, development and characterization issues of these plasma switches have been presented. The research work on development of high voltage (≥ 30 kV) and high current (≥ 5 kA) PSS and thyratrons for high energy applications has also been presented. The recent research work on the few PS discharge based plasma cathode electron (PCE) guns for the generation of high energetic, intense and focused electron beams and also their applications for plasma-assisted slow wave oscillator ‘Pasotron’ will also be presented. Discussions have also been made for the areas of further research on novel pseudospark (PS) discharge technologies for the generation of EUV/X-ray radiations for the potential biological, spectroscopy and surface modification applications.

Prof. Amarendra Rajput, Former Professor

Dibrugarh University, Assam University and Haramaya University (Ethiopia)

Date, time & venue: 02/11/2018, 3:00 pm, CPP-IPR Seminar Hall

Professor Rajput earned his B.Sc. and M.Sc. degree from University of Delhi and Ph.D. Degree from IIT Madras. His research intestate includes Quantum Mechanics, Cosmology and Solid State Theory. He taught at postgraduate level for almost 37 years at Dibrugarh University and Assam University. Then he moved to Haramaya University in Ethiopia on the invitation from Ministry of Education, Ethiopia in 2008 and spent around 10 years in Ethiopia. At present, he is teaching at Royal Global University, Guwahati.

Dr. Partha Saikia, Post Doctoral Fellow

Institute of Physics, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile

Date, time & venue: 05/10/2018, 3.00 PM, CPP-IPR Seminar Hall

We investigate the discharge behavior of dual frequency capacitively coupled plasmas driven at 2.26 and 13.56 MHz experimentally and by a non-linear global model. In the experiment, the pressure is varied from 1 mtorr to 60 mtorr. The electron density, electron temperature as well as the ion current are measured as a function of the low frequency power at fixed values of the high frequency power for different pressures. It is found that the frequency coupling and the secondary electrons have profound effects on the discharge dynamics, thus limiting the separate control of the mean ion energy and the flux. The plasma parameters are then incorporated as inputs of the numerical model and the model outputs are compared with the measured value of the DC self-bias, a quantity that determines the mean ion energy. A good quantitative correspondence between them is obtained. We predict the excitation of the Plasma series resonance (PSR) effect using the numerical model and the influence of the operating pressure on the excitation of the PSR is also studied using this model.

Prof. Arun Sarma

School of Advanced Sciences (SAS), VIT University Chennai, Vandalur-Kelambakkam Road, Chennai-600127, Tamil Nadu, India

Date, time & venue: 21/05/2018, 3.00 PM, CPP-IPR Seminar Hall

Diamond like carbon (DLC) coating worked as an abrasive coating to reduce wear and increase life time of products, normally used in presence of lubricant. DLC coating can also be used to strength mechanical properties such as hardness and toughness. Looking these advantages of DLC coating, coating has been done on samples used in automobile industries to enhance the life time of samples in presence of lubricant. Depending on the sample materials, some interlayer coating is essential to enhance the adhesion properties of DLC. Both sputtering and PECVD techniques have been used for coating process after considering all necessary pre conditions. Optical properties of coating have been studied using Raman spectroscopy, Photoluminescent spectroscopy, ellipsometer. Structural properties were understood using X-ray diffractometer, SEM-EDAX and AFM. Mechanical properties of the coated samples were studied using Micro-hardness tester, Nano-indentation, scratch tester etc. Fianlly its tribological properties were examined with the help of electro-chemical analysis.

Prof. Nilakshi Das

Department of Physics, Tezpur University, Assam, India

Date, time & venue: 29/01/2016, 3.00 PM, CPP-IPR Seminar Hall

Prof. D. J. Saikia, Vice-Chancellor

Cotton College State University, Guwahati. Senior Professor, National Centre for Radio Astrophysics, TIFR, Pune, India

Date, time & venue: 21/12/2015, 11.00 AM, CPP-IPR Seminar Hall

Prof. A. Srinivasan

Department of Physics, IIT, Guwahati, India

Date, time & venue: 09/11/2015, 03.00 PM, CPP-IPR Seminar Hall

We know that the behaviour of materials with size in between microscopic and macroscopic length scales is very different. While most of us understand how the optical and catalytic properties of materials vary with size and dimension dependence in this mesoscale (or nanoscale), magnetic properties of nanoscale materials is not well known. There are some very unique magnetic phenomena displayed by certain nanoscale magnetic particles which have no equivalence in the other two length scales such as superparamagnetism, giant magneto-resistance, exchange bias, 2-d electron gas, etc. Since these phenomena are exhibited by materials with different degrees of quantum confinement, they have their foundations in quantum physics. Such novel phenomena have many applications ranging from health sector to new generation electronic and spintronic devices. Some of these materials can be synthesized by simple laboratory based methods available in most academic and research institution. Since the processing route has a bearing on their properties, there are many interesting challenges in this field which are waiting to be tackled. The physics behind some of these interesting phenomena will be discussed in this talk along with examples. Some of the striking applications of these low dimensional magnetic materials will also be mentioned in the talk.