Xenon excimer emission from pulsed high-pressure capillary microdischarges

Intense xenon vacuum ultraviolet (VUV) emission is observed from a high-pressure capillary cathode microdischarge in direct current operation, by superimposing a high-voltage pulse of 50 ns duration. Under stagnant gas conditions, the total VUV light intensity increases linearly with pressure from 400 to 1013 mbar for a fixed voltage pulse. At fixed pressure, however, the VUV light intensity increases superlinearly with voltage pulse height ranging from 0.8 to 2.8 kV. Gains in emission intensity are obtained by inducing gas flow through the capillary cathode, presumably because of excimer dimer survival due to gas cooling

Xenon excimer emission from multicapillary discharges in direct current mode

Microdischarges in xenon have been generated in a pressure range of 400–1013 mbar with a fixed flow rate of 100 sccm. These microdischarges are obtained from three metallic capillary tubes in series for excimer emission. Total discharge voltage is thrice as large as that of a single capillary discharge tube at current levels of up to 12 mA. Total spectral irradiance of vacuum ultraviolet (VUV) emission also increases significantly compared to that of the single capillary discharge. Further, the irradiance of the VUV emission is strongly dependent on pressure as well as the discharge current

EFFECT OF FOLIAR APPLICATION OF ZINC ON YIELD OF WHEAT GROWN UNDER WATER STRESS CONDITION

A Thesis Submitted to the Faculty of Agriculture Sher-e-Bangla Agricultural University, Dhaka, in partial fulfilment of the requirements for the degree of MASTER OF SCIENCE IN SOIL SCIENCE SEMESTER: JANUARY.,JUNE, 2014A field experiment was carried out to study the effect of foliar application of zinc on growth and yield of wheat (BARI goni-25) grown under water stress condition in the research fann of the Sher-e-Bangla Agricultural University (SAU), during October 2013 [0 February 2014. The experiment was designed in randomized complete block with factor A (representing irrigation) and factor B (as foliar Zn application). There were in total 16 treatments comprising 4 irrigation treatments (regular irrigation, skipped irrigation at crown root initiation. skipped irrigation at booting stage and skipped irrigation at beading and flowering stage of growth) and four foliar application of zinc (control, 0.02%, 0.04% and 0.06% of zinc). Zinc Sulphate Monohydrate (ZnS04.HzO) was used as a sourc-e of Zn. The interaction effect of irrigation and foliar application of zinc on yield components of wheat was significant. The highest yield (2.90 t ba-I) was recorded in skipping irrigation at flowering and heading stage with 0.06% foliar application of zinc. Water stress at crown root initiation stage had the most negative effect on growth and yield. Skipping irrigation at booting stage and skipping irrigation at Ilowering and beading stage with 0.04% foliar application of zinc gave the identical yield in regular with control 0.04% and 0.06% foliar application of zinc. Thus, foliar application of zinc played a major role on yield and yield components of wheat at later stages of growth, The optimum dose was appeared as 0.04% foliar application of zinc for grain yield of wheat

Diode Like Attributes in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing

Neuromorphic computing (NC) is considered as a potential vehicle for implementing energy-efficient artificial intelligence (AI). To realize NC, several materials systems are being investigated. Among them, the spin-orbit torque (SOT) -driven domain wall (DW) devices are one of the potential candidates. To implement these devices as neurons and synapses, the building blocks of NC, researchers have proposed different device designs. However, the experimental realization of DW device-based NC is only at the primeval stage. In this study, we have proposed and investigated pine-tree-shaped DW devices, based on the Laplace force on the elastic DWs, for achieving the synaptic functionalities. We have successfully observed multiple magnetization states when the DW was driven by the SOT current. The key observation is the asymmetric pinning strength of the device when DW moves in two opposite directions (defined as, xhard and xeasy). This shows the potential of these DW devices as DW diodes. We have used micromagnetic simulations to understand the experimental findings and to estimate the Laplace pressure for various design parameters. The study leads to the path of device fabrication, where synaptic properties are achieved with asymmetric pinning potential

Crop Diversification Strategy against Stunting Diversification Index: An Evidence from West Bengal, India

Abstract The food basket of the world is diversifying towards high-value crops. A diversified cropping system offers multifaceted opportunities to the farmers. The nature of diversification in developing countries is significantly different at both farming and cropping levels; thus, it is felt important to investigate such a study at different land size holding. This study is conducted to examine the trends of crop diversification under different land size classes in the state of West Bengal, which assumes as a representative image of India. The study uses secondary data obtained from Agriculture Census for the year 1995-96 and 2015-16. Gibbs-Martin’s technique is employed for the calculation of the diversification index. Overall analyses reveal that the stunting change in diversification is noted in marginal, small, large, and all land classes. The implication of such growth pushes the rural economy in a skewed direction.</jats:p

Untersuchung einer hohen Leistung, Hochdruckfunkenstreckeschalter mit hoher Wiederholrate

Micro plasmas in a pressurized spark gap switch were under investigation in the present dissertation. In contrast to the requirements of commonly used high power switches, this work was focused on investigations of a high repetition rate and simultaneously maintaining a fast switching time at a low energy transfer per pulse. The spark gap was operating in a free running mode, without any triggering. The breakdown was only initiated by overvoltage. For this particular switch, a theoretical charging strategy and a novel dual-power supply scheme based on an open plasma gap was developed. This circuit scheme was successfully used in the experiment. A computer simulation code (PSpice) was used to understand the influence of circuit parameters on the dielectric recovery of the plasma gap. Based on these circuit parameters, a resonant charging scheme was established. Furthermore, a PSpice spark gap model was used to understand the effect of some discharge parameters on pulsed plasmas. The discharge parameters determine the duration and decay of the plasma conducting channel. The decay of this conducting channel was improved by variation of different circuit schemes and spark gap geometries. The study was further extended to establish an efficient recovery process of the gas density. The spark gap itself was integrated in a 50 &#61527; transmission line. SF6 gas in a pressure range of 1–1.5 bars was used. The electrode gap distances were adjusted between 200 µm and 300 µm. The input power for generating miniaturized discharges within the electrode gap was 12 to 20 watts. The Pulse Repetition Rate (PRR) of spark plasmas exceeded 1 MHz with a rise time of switched pulses in the transmission line below 200 ps. The efficiency of charging up to re–breakdown voltages of the spark gap exceeded 60 %. The efficiency of energy transfer by switched pulses in the transmission line exceeded 95 %. The lifetime of the spark gap electrodes exceeded 109 impulses. In essence, the switching behavior by micro plasmas enabled the state–of–the–art with simplicity, low input power, very high PRR, lower rise time and smaller volume. The experimental results especially the PRR exceed the up to now known values of the plasma closing switches such as spark gaps, thyratrons etc. The physical explanation of breakdown phenomena in gases and dielectric recovery of the plasma gap has been worked out as the basis of this research study. The insight into our results will spur interest in many applications particularly in the repetitive pulsed power technology.Gegenstand dieser Arbeit war die Untersuchung und Optimierung der plasmaphysikalischen und der elektrischen Parameter einer kurz gepulsten Hochleistungsfunkenstrecke bei gleichzeitig hoher Pulswiederholfrequenz. Die Funkenstrecke selbst wurde ohne externe Triggerung betrieben. Der Spannungszusammenbruch zwischen den Elektroden der Funkenstrecke wurde durch Überspannung initiiert. Um diese hohen Spannungen bei gleichzeitig hoher Repetitionsrate der Funkenstrecke aufrecht zu erhalten wurde ein neuartiger resonanter Lademechanismus, basierend auf zwei gekoppelten Hochspannungsversorgungen entwickelt und erfolgreich eingesetzt. Zur Optimierung der elektrischen Parameter des resonanten Ladekreises wurde ein Computersimulationsprogramm namens PSpice verwendet. Mit diesem Programm war es möglich den Einfluss der elektrischen Parameter des Stromkreises auf das schnelle Schaltverhalten der Funkenstrecke zu untersuchen. Zusätzlich konnten mit diesem Programm Simulationen zur Optimierung der Funkenstreckengeometrie und der Plasmaparameter in Abhängigkeit der elektrischen Parameter des resonanten Ladekreises durchgeführt werden. Ein wichtiges Ergebnis aus den Simulationen war eine verbesserte Wiederverfestigung des leitfähigen Plasmakanals mit einer Optimierung der Elektrodengeometrie der Funkenstrecke. Bei den experimentellen Messungen zur Wiederverfestigung der Funkenstrecke wurde zusätzlich der Gasdruck der Funkenstrecke berücksichtigt. Um Reflexionen des elektrischen Signals am offenen Ende der Funkenstrecke zu vermeiden wurde beim experimentellen Aufbau die Impedanz der Funkenstrecke an die des 50 &#61527; Kabels angepasst. Während der Experimente wurde zur Erhöhung der Durchbruchsspannung SF6 als Arbeitsgas verwendet. Der untersuchte Druckbereich des Isolationsgases innerhalb der gekapselten Funkenstrecke lag zwischen 1 und 1,5 bar. Der Abstand des Elektrodenpaares konnte beim experimentellen Aufbau zwischen 200 µm und 300 µm variiert werden. Die Ausgangsleistung der resonanten Hochspannungsversorgung mit der die Funkenstrecke betrieben wurde betrug zwischen 11 und 16 Watt. Ein wichtiges Ergebnis aus den Simulationen und den experimentellen Messungen war die Optimierung der Pulswiederholfrequenz und den erzielten Stromanstiegszeiten der Funkenstrecke. Es wurde hierbei eine Wiederholrate von mehr als 1 MHz bei einer Stromanstiegszeit von weniger als 200 ps erreicht. Die Effizienz der Ladespannung der oben genannten Pulswiederholungsfrequenz entlang der Funkenstrecke betrug mehr als 60 %. Die Effizienz der übertragenen Energieimpulse in der Koaxialleitung lag über 95 %. Zusätzlich wurde mit der optimierten Elektrodengeometrie der Funkenstrecke eine Lebensdauer von mehr als 109 Pulsen erreicht. Ein weiteres wichtiges Ergebnis der experimentellen Messungen mit der neu konzipierten Funkenstrecke ist das Erreichen der hohen Wiederholfrequenz. Gegenüber herkömmlichen Plasmaschaltern, wie z.B. Thyratrons oder Funkenstrecken, liegt dieser Wert um Großenordnungen höher. Die hierfür ausgearbeitete Theorie der Durchbruchscharakteristik und Wiederverfestigung von Gasen diente als Grundlage zur Ausarbeitung der in dieser Arbeit erreichten Ziele. Die aus den Experimenten und Simulationen gewonnen Ergebnisse und die damit aufgestellten Modelle können in vielen Bereichen der Leistungs- und Impulstechnik eine wichtige Hilfestellungen bieten