Power Research

Sabyasachi Mitra ¹, Vishnu Sharma ¹, Senthil Kalyandrum ¹, Romesh Chandra ¹, Sandeep Singh ¹, Rakhee Menon ¹, Ankur Patel ¹, Amitava Roy ¹, Archana Sharma ¹, Krishna Kanakgiri ², Mayank Mishra ²

Affiliations
1 Accelerator and Power Pulse Division, Bhabha Atomic Research Centre, Mumbai, IN
2 Veermata Jijabai Technological Institute, Mumbai, IN

Abstract

In this paper effect of stray capacitance on output voltage of the Marx Generator is studied. Stray capacitances formed between high voltage metallic structures of Marx generator and its ground enclosure play a critical role in determining the voltage and rise time of the output pulse. With increase in enclosure diameter erected leakage inductance increases and stray capacitance reduces, with decrease and vice versa. Eventually in both the cases output voltage reduces and rise time increases. This effect is predominant in fast rising low energy MARX generators having low erected capacitances. In this paper effort has been made to quantify these effects. Simulations were carried out for different enclosure structures to find out their effect on output voltage and rise time with a fixed load. It was observed that conical enclosure helps in mitigating this problem in MARX generator. Simulations were also carried out to optimize the flaring angle of the conical enclosure to obtain maximum output voltage. Simulated results are experimentally validated using a 22 stage 450 kV MARX generator. Details of the analysis, simulations and experimental results are narrated thoroughly in this paper.

Keywords

Marx Generator, stray capacitance, rise time, stray inductance

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Ravindra Kumar Sharma ¹, Archana Sharma ¹

Affiliations
1 Homi Bhabha National Institute, BARC Mumbai-400 085, IN

Abstract

To date, thorough study does not exist for multichannel operation of field distortion planner spark gaps. There is continuous demand to generate the complex phenomenon of multichannel in spark gaps. Seven channel discharges has been realised with compact field distortion trigger of 40 mJ, 100 V/ns, first of its kind. Spark gap is environmentally sealed and operated under atmosphere pressure. Copper trigger pins are replaced with brass material to enhance the life and uniform discharge. A high speed streak camera is exploited to catch the images of dedicated discharge channels. Streak images are useful to understand the formation of multiple arcs during triggering. Spark gap programming is electrically tested for number of plasma channels. This new concept is implemented by selective hard wiring of trigger pins. It is inferred that the multi-channel switching is beneficial for reduction of inductance (10 nH), increase in peak discharging current (50 kA) and life of 500 shots. It is experimentally confirmed a good life (100 shots) for higher current of 120 kA. Switch is tested without intermediate cleaning or air flushing. All the electrodes assembly and environment sealing is achieved in a palm top size of length: 120mm, width: 65mm and height: 25 mm. This paper presents study of electrode material, programmable seven channels discharge capability, circuit inductance, delay time and plasma channel's jitter using streak photography as a function of test voltage and number of channels.

Keywords

High voltage, pulsed power, inductance, plasma channel, spark gap.

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Gynendra Kumar ¹, Archana Sharma ¹, R. Sarathi ²

Affiliations
1 Homi Bhabha National Institute, Accelerator and Pulse Power Division , Mumbai-400085, IN
2 Department of Electrical engineering, Indian Institite of technology, Madras, Chennai, IN

Abstract

In this review paper after various reported data from 2000 to 2016 published in IEEE and science direct, are analyzed and discussed to explore the feasibility of pulsed power application in cell biology. Targeting inhabitation of cancer/tumor proliferation treatment as main fields, some other associated topics e.g. effect on plasma membrane, apoptosis induction etc. are investigated in vitro and in vivo, it summarizes, HOW the nano second Pulse Electric Field (nsPEF) affects eukaryotic cells that are healthy as well as that are affected by tumor/cancer i.e. unhealthy. Term electroporation came into the picture which stands for opening pore in cell membrane using pulse of electricity, to introduce DNA or chromosomes into bacteria or other cells. Width of the applied electrical pulse used also caused different cellular effects, pulses longer than 100μs, in electroporation, delivers DNA, protein, small drugs and fluorescent indicators across the plasma membrane and causes moderate levels of Phosphatidyl Serine (PS) translocation at the Plasma Membrane, while shorter pulses less than 1μs are central to intracellular effects such as apoptosis induction (programmed cell death) and higher levels of Phosphatidyl Serine (PS) translocation. In addition, nsPEFs acts as cellular stress that introduces translational suppression. Ultra-short electricity i.e. nsPEFs can reach intra cellular component directly without membrane destruction causes apoptosis induction (programmed cell death). Also it has been found that direct current produced by applied voltage induces specific biological healing of tissues near the electrodes, also the effect of current is same as in ionizing radiation of tumor therapy. Chemotherapeutic drugs along with nsPEF reduces dose of both types of treatments. Also, nsPEFs causes transient activation of signaling pathways involving Mitogen-Activated Protein Kinases (MAPKs). Now days, nsPEFs are recognized as unique tool in life science.

Keywords

Nano second pulsed electric field, apoptosis induction, electroporation

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S. K. Dond ¹, M. R. Kulkarni ², Archana Sharma ², G. K. Dey ²

Affiliations
1 Homi Bhabha National Institute.Anushaktinagar, Mumbai, Maharashtra 400094, IN
2 Bhabha Atomic Research Centre Trombay, Mumbai, Maharashtra 400085, IN

Abstract

Electromagnetic forming is a high velocity forming process where Lorentz force is used for workpiece expansion. The required velocity for forming is achieved by a pulsed magnetic field. In the present work, Electromagnetic expansions of aluminum tubes are carried out using 20 kJ systems at different energies. A 2D coupled numerical simulation is also performed that shows the tube velocity and deformation under transient magnetic pressure. From the observed results, magnetic to mechanical pressure relation is studied that helps in controlled forming operation.

Keywords

Electromagnetic forming, Magnetic pressure, Plastic deformation, Coupled simulation

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