The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2&...The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2×10^8 neutrons/shot(of fast D-D neutrons with typical energy^2.45 Me V)at^1.8 k J energy discharge are reported.From the detailed analysis of the experimental characterization and simulation results of this system,it has been conclusively revealed that specifically in plasma focus devices with larger static inductance:(i)pinch current is a reliable and more valid neutron yield scaling parameter than peak current,(ii)the ratio of pinch/peak current improves as static inductance of the system reduces,(iii)the benign role of the higher static/pinch inductance ratio enables the supply of inductively stored energy in densely pinched plasma with a larger time constant and it is well depicted by the extended dip observed in the discharge current trace,(iv)there is the need to redefine existing index values of the pinch(Ipinch^4.7)and peak(Ipeak^3.9)currents in neutron yield scaling equations to higher values.展开更多
The persistent rise in concentrations of greenhouse gases (GHGs) in the earth’s atmosphere is responsible for global warming and climate change. Besides the known source of GHGs emissions like energy, industry, and a...The persistent rise in concentrations of greenhouse gases (GHGs) in the earth’s atmosphere is responsible for global warming and climate change. Besides the known source of GHGs emissions like energy, industry, and agriculture, intrinsic emissions from natural inland water bodies like wetland, rivers, reservoirs, estuaries, etc. have also been identified as other hotspots of GHGs emission and gaining the attention of the scientific communities in recent times. Inland fisheries in India are threatened by climate changes such as a change in temperature, precipitation, droughts, storm, sea-level rise, saltwater intrusion, floods that affect mostly the production, productivity and ultimately affect the fishers’ livelihood. There are, however, different mitigation and adaptation strategies to cope with the effects of climate change. Carbon sequestration and other related management interventions are one of the options available minimizing GHGs emissions from inland open waters, particularly the wetlands and coastal mangroves which are well known worldwide for their significant role in the storage of carbon. Assessment of C efflux from exposed sediments in dry streams, reservoirs, lakes, rivers, and ponds into the atmosphere can be considered imperative for a better understanding of their role as a C-sink or as a C-source to the atmosphere.展开更多
Ganga is the most prestigious river of India.The COVID-19 lockdown may have forced us to stay indoors,but it has been boon for pollution-ridden Ganga and Yamuna.Plankton is tiny organisms drifting with water current,i...Ganga is the most prestigious river of India.The COVID-19 lockdown may have forced us to stay indoors,but it has been boon for pollution-ridden Ganga and Yamuna.Plankton is tiny organisms drifting with water current,influenced by river physical and chemical factors.During lockdown anthropogenic factors were reduced which affected water and plankton quality.Plankton samples were collected from the upstream of the river Ganga(Shankerghat,latitude 25030’28”N and longitude,81052’10”E)and Yamuna(near boat club,latitude 25024’29”N and longitude 81054’50”E)at Prayagraj,during national lockdown.In the before lockdown period(2019),total 28 planktonic taxa were recorded from the river Ganga,among them 10 taxa from Bacillariophyceae,15 from Chlorophyceae and 3 from Myxophyceae.While during LD period total 54 genera with 86 species was recorded(Bacillariophyceae 10 taxa,Chlorophyceae 23 taxa,Myxophyceae 9 taxa,Euglenophyceae 2 taxa,Dianophyceae,1,Rotiferea 7 taxa,Protozoa 2 taxa).Various species of green algae were observed in this small period of lockdown,some species were not observed since a long,like Pediastrum tetras,Scenedesmus abundans,Ankistrodesmus fusiformis,and Brachionus angularis.Various species of phytoplankton and zooplankton were in reproductive phase because river was flowing silently,without any internal and external disturbance.Ganga was more affected by anthropogenic activity and factory discharge than Yamuna So lack of chemicals in the water and minimum human interference favoured auto rejuvenation of Ganga in terms of plankton quality,diversity and reproduction behaviour.Such type of environmental changes may stimulate for origin of new species and disappear or reappear of various aquatic species.展开更多
文摘The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2×10^8 neutrons/shot(of fast D-D neutrons with typical energy^2.45 Me V)at^1.8 k J energy discharge are reported.From the detailed analysis of the experimental characterization and simulation results of this system,it has been conclusively revealed that specifically in plasma focus devices with larger static inductance:(i)pinch current is a reliable and more valid neutron yield scaling parameter than peak current,(ii)the ratio of pinch/peak current improves as static inductance of the system reduces,(iii)the benign role of the higher static/pinch inductance ratio enables the supply of inductively stored energy in densely pinched plasma with a larger time constant and it is well depicted by the extended dip observed in the discharge current trace,(iv)there is the need to redefine existing index values of the pinch(Ipinch^4.7)and peak(Ipeak^3.9)currents in neutron yield scaling equations to higher values.
文摘The persistent rise in concentrations of greenhouse gases (GHGs) in the earth’s atmosphere is responsible for global warming and climate change. Besides the known source of GHGs emissions like energy, industry, and agriculture, intrinsic emissions from natural inland water bodies like wetland, rivers, reservoirs, estuaries, etc. have also been identified as other hotspots of GHGs emission and gaining the attention of the scientific communities in recent times. Inland fisheries in India are threatened by climate changes such as a change in temperature, precipitation, droughts, storm, sea-level rise, saltwater intrusion, floods that affect mostly the production, productivity and ultimately affect the fishers’ livelihood. There are, however, different mitigation and adaptation strategies to cope with the effects of climate change. Carbon sequestration and other related management interventions are one of the options available minimizing GHGs emissions from inland open waters, particularly the wetlands and coastal mangroves which are well known worldwide for their significant role in the storage of carbon. Assessment of C efflux from exposed sediments in dry streams, reservoirs, lakes, rivers, and ponds into the atmosphere can be considered imperative for a better understanding of their role as a C-sink or as a C-source to the atmosphere.
文摘Ganga is the most prestigious river of India.The COVID-19 lockdown may have forced us to stay indoors,but it has been boon for pollution-ridden Ganga and Yamuna.Plankton is tiny organisms drifting with water current,influenced by river physical and chemical factors.During lockdown anthropogenic factors were reduced which affected water and plankton quality.Plankton samples were collected from the upstream of the river Ganga(Shankerghat,latitude 25030’28”N and longitude,81052’10”E)and Yamuna(near boat club,latitude 25024’29”N and longitude 81054’50”E)at Prayagraj,during national lockdown.In the before lockdown period(2019),total 28 planktonic taxa were recorded from the river Ganga,among them 10 taxa from Bacillariophyceae,15 from Chlorophyceae and 3 from Myxophyceae.While during LD period total 54 genera with 86 species was recorded(Bacillariophyceae 10 taxa,Chlorophyceae 23 taxa,Myxophyceae 9 taxa,Euglenophyceae 2 taxa,Dianophyceae,1,Rotiferea 7 taxa,Protozoa 2 taxa).Various species of green algae were observed in this small period of lockdown,some species were not observed since a long,like Pediastrum tetras,Scenedesmus abundans,Ankistrodesmus fusiformis,and Brachionus angularis.Various species of phytoplankton and zooplankton were in reproductive phase because river was flowing silently,without any internal and external disturbance.Ganga was more affected by anthropogenic activity and factory discharge than Yamuna So lack of chemicals in the water and minimum human interference favoured auto rejuvenation of Ganga in terms of plankton quality,diversity and reproduction behaviour.Such type of environmental changes may stimulate for origin of new species and disappear or reappear of various aquatic species.
