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Electrodeless plasma thrusters for spacecraft: a review

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Plasma Science and Technology 2017年第8期19卷 1-24页

作者： S N BATHGATE m m m BILEK d R mCKENZIE Applied and Plasma Physics School of PhysicsUniversity of Sydney

The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more durable than presently deployed thrusters that use electrodes such as gridded ion,Hall thrusters, arcjets and resistojets. Like other plasma thrusters, electrodeless thrusters have the advantage of reduced fuel mass compared to chemical thrusters that produce the same thrust. The status of electrodeless plasma thrusters that could be used in communications satellites and in spacecraft for interplanetary missions is examined. Electrodeless thrusters under development or planned for deployment include devices that use a rotating magnetic field; devices that use a rotating electric field; pulsed inductive devices that exploit the Lorentz force on an induced current loop in a plasma; devices that use radiofrequency fields to heat plasmas and have magnetic nozzles to accelerate the hot plasma and other devices that exploit the Lorentz force. Using metrics of specific impulse and thrust efficiency, we find that the most promising designs are those that use Lorentz forces directly to expel plasma and those that use magnetic nozzles to accelerate plasma.

关键词： spacecraft a review propellant Lorentz thrust rotating radiofrequency erosion presently exploit

Prediction and analysis of process failures by ANN classification during wire-Edm of Inconel 718

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Advances in manufacturing 2020年第4期8卷 519-536页

作者： Abhilash P.m. Chakradhar d. department of mechanical Engineering Indian Institute of Technology PalakkadPalakkadKeralaIndia

Wire breakages and spark absence are two typical machining failures that occur during wire electric discharge machining(wire-Edm),if appropriate parameter settings are not *** after several attempts to optimize the process,machining failures cannot be eliminated completely.A n offline classification model is presented herein to predict machining *** aim of the current study is to develop a multiclass classification model using an artificial neural network(ANN).The training dataset comprises 81 full factorial experiments with three levels of pulse-on time,pulse-off time,servo voltage,and wire feed rate as input *** classes are labeled as normal machining,spark absence,and wire *** model accuracy is tested by conducting 20 confirmation experiments,and the model is discovered to be 95%accurate in classifying the machining *** effects of process parameters on the process failures are discussed and analyzed.A microstructural analysis of the machined surface and worn wire surface is *** developed model proved to be an easy and fast solution for verifying and eliminating process failures.

关键词： Wire electric discharge machining(wire-Edm) Process failure Spark absence Wire breakage Artificial neural network(ANN)classification Failure prediction

Computational Studies of Flow through Cross Flow Fans-Effect of Blade Geometry

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Journal of Thermal Science 2005年第3期14卷 220-229页

作者： m . GOVARdHAN d. LAKSHmANA SAmPAT School of mechanical Engineering Universiti Malaysia Sabah Sabah Malaysia ProfessorThermal Turbomachines Laboratory Department of Mechanical Engineering Indian Institute of Technology Madras Chennai India

This present paper describes three dimensional computational analysis of complex internal flow in a cross flow fan. A commercial computational fluid dynamics (CFd) software code CFX was used for the computation. RNG k-ε two equation turbulence model was used to simulate the model with unstructured mesh. Sliding mesh interface was used at the interface between the rotating and stationary domains to capture the unsteady interactions. An accurate assessment of the present investigation is made by comparing various parameters with the available experimental data. Three impeller geometries with different blade angles and radius ratio are used in the present study. maximum energy transfer through the impeller takes place in the region where the flow follows the blade curvature. Radial velocity is not uniform through blade channels. Some blades work in turbine mode at very low flow coefficients. Static pressure is always negative in and around the impeller region.

关键词： cross flow fans computational fluid dynamics quasi steady state multiple frames of reference

modelling two-layer nanofluid flow in a micro-channel with electro-osmotic effects by means of Buongiorno’s model

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Applied mathematics and mechanics(English Edition) 2020年第1期41卷 83-104页

作者： m.d.K.NIAZI Hang XU State Key Lab of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE)School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong University

A fully developed steady immiscible flow of nanofluid in a two-layer microchannel is studied in the presence of electro-kinetic ***’s model is employed for describing the behavior of *** from the previous studies on two-layer channel flow of a nanofluid,the present paper introduces the flux conservation conditions for the nanoparticle volume fraction field,which makes this work new and unique,and it is in coincidence with practical *** governing equations are reduced into a group of ordinary differential equations via appropriate similarity *** highly accurate analytical approximations are *** physical quantities and total entropy generation are analyzed and discussed.A comparison is made to determine the significance of electrical double layer(EdL)effects in the presence of an external electric *** is found that the Brownian diffusion,the thermophoresis diffusion,and the viscosity have significant effects on altering the flow behaviors.

关键词： electrical double layer(EdL) entropy generation micro-channel nanofluid

Preliminary performance analysis and optimization based on 1d neutronics model for Indian dEmO HCCB blanket

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Plasma Science and Technology 2020年第8期22卷 184-191页

作者： d AGGARWAL C dANANI m Z YOUSSEF Institute for Plasma Research GandhinagarGujarat 382428India Homi Bhabha National Institute(HBNI) AnushaktinagarMumbai 400094India University of California-Los Angeles Los AngelesCA 90095United States of America

India,under its breeding blanket R&d program for dEmO,is focusing on the development of two tritium breeding blanket concepts;namely the lead-lithium-cooled ceramic breeder and the helium-cooled ceramic breeder(HCCB).The study presented in this paper focuses on the neutronic design analysis and optimization from the tritium breeding perspective of the HCCB *** Indian concept has an edge-on configuration and is one of the variants of the helium-cooled solid breeder blanket concepts proposed by several partner countries in *** Indian HCCB blanket having lithium titanate(Li2TiO3)as the tritium breeder and beryllium(Be)as the neutron multiplier with reduced-activation ferritic/martensitic steel structure aims at utilizing the low-energy neutrons at the rear part of the *** aim of the optimization study is to minimize the radial blanket thickness while ensuring tritium self-sufficiency and provide data for further neutronic design and thermal-hydraulic layout of the HCCB *** is found that inboard and outboard blanket thicknesses of 40 cm and 60 cm,respectively,can give a tritium breeding ratio(TBR)>1.3,with 60%6Li enrichment,which is assumed to be sufficient to cover potential tritium losses and associated *** results also demonstrated that the Be packing fraction(PF)has a more profound impact on the TBR as compared to 6Li enrichment and the PF of Li2TiO3.

关键词： dEmO helium-cooled ceramic breeder blanket neutronic optimization study tritium breeding ratio

Theoretical study of differential cross sections for the ionization of helium by fast proton impact

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Chinese Physics B 2024年第11期33卷 255-264页

作者： m mondal B mandal T mistry d Jana m Purkait department of Physics Ramakrishna Mission Residential CollegeNarendrapurKolkata-700103India

We present the angular distribution of the ejected electron for single ionization of He by fast proton impact.A fourbody formalism of the three-Coulomb wave is applied to calculate the triple differential cross sections at several impact energies in the scattering,perpendicular and azimuthal ***,the three-body formalism of three-Coulomb,two-Coulomb and first Born approximation models has also been used to study the many-body effect on electron emission and the validity of the *** the three-Coulomb wave model,the final state wave function incorporates distortion due to the three-body mutual Coulombic *** this formalism,we use an uncorrelated and correlated Born initial state,which consists of a plane wave for the incoming projectile times a two-electron bound state wavefunction of the helium atom representing the 1s2(1S)***,in the case of the three-body formalism,the initial state wavefunction consists of a long-range Coulomb distortion for the incoming projectile and one active electron of the He atom described by the Roothaan–Hartree–Fock *** structure with a single or two peaks with unequal intensity is observed in the angular distributions of the triple differential cross sections for the different kinematic *** addition,the influence of static electron correlations is investigated using different bound state wavefunctions for the ground state of the He *** the four-body formalism,the present computations are very fast by reducing a nine-dimensional integral to a two-dimensional real *** the simplicity and speed of the proposed quadrature,the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other theories.

关键词： ionization cross sections collision atoms ions

Coating particles using liquids and foams based on viscous formulations with industrial mixers: Batch operation

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Particuology 2020年第3期18卷 13-24页

作者： d.Kontziampasis m.S.manga d.W.York School of Chemical and Process Engineering Faculty of EngineeringUniversity of LeedsLS29JTLeedsW.YorkshireUK

Particle or powder coating with viscous liquids has been essential in industry for surface modification purposes to induce and enhance specific *** paper evaluates the performance of using foams (of different bubble diameters) versus liquids as a means of coating powder beds based on viscous liquid *** with viscous liquids present numerous industrial challenges and therefore preparing foam equivalents can render the liquid component weak enough (through pre shearing to form the foam),to allow it to break up and coat particles under the shear forces exerted in a mixing *** this study,two shear mixers are used;the first type consists of paddles in different configurations attached to a single rotating shaft,whilst the second type is a commercial twin screw mixer (TSm).The quality of coating achieved on the bulk powder bed using liquids and foams (stained with a dye) is assessed by image analysis to determine the homogeneity of the color *** addition,scanning electron microscopy provides a tool to further investigate the coating quality of individual particles from the bulk *** results show that large bubble (centimeter size) foams are much more effective at distributing within the fluidized powder bed compared to the starting viscous liquid and small bubble foams (submillimeter size).Furthermore,there is a maximum ratio of foam to powder beyond which agglomeration occurs and is insufficient to fully coat the *** of individual particles is achieved in the case of the TSm,whereas SEm proves that the single shaft paddle mixer crushes the particles and subsequently granulates them together to form granules of a size comparable to the size of coated particles seen after coating with the TSm.

关键词： Powder coating Viscous liquid Foam Image analysis Foam rheology Surface modification

Jet flows from bubbles during subcooled pool boiling on micro wires

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Science China(Technological Sciences) 2005年第4期48卷 385-402页

作者： d. m. Christopher Laboratory of Phase Change and Interfacial Transport Phenomena Department of Thermal Engineering Tsinghua University Beijing 100084 China

An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25―100 μm. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to visually observe the bubble dynamics. For highly subcooled boiling at moderate heat fluxes, the bubbles generally remained attached to the micro heating wires and bubble-top jet flows were clearly observed. Smaller bubbles usually had stronger bubble-top jet flows, while larger bubbles seemed to produce multi-jet flows. The structures of the bubble-top jet flows, as well as multi-jet flows, were proposed from the experimental observation. A model was developed to describe jet flow phenomena from bubbles on micro wires. Numerical simulations for bubbles having diameter of 0.03 and 0.06 mm showed that both the bubble-top and multi-jet flows were induced by a strong marangoni effect due to high temperature gradients near the wire. The predicted velocity magnitudes and flow structures agreed very well with experimental measurements. The bubble size relative to the wire is an important factor affecting the jet flow structure. For a 0.03 mm bubble on a 0.1 mm wire, only a bubble-top jet flow forms, while a complex multi-jet flow pattern forms around the bubble with a weak bubble-top jet and two side jet flows for a 0.06 mm bubble.

关键词： subcooled boiling, bubble, multi-jet, jet flow, PIV, marangoni, CFd.

Nucleus-acoustic solitary waves in self-gravitating degenerate quantum plasmas

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Chinese Physics B 2018年第4期27卷 191-197页

作者： d m S Zaman m Amina P R dip A A mamun department of Physics Jahangirnagar University department of EEE Bangladesh University of Business and Technology(BUBT)

Nucleus-acoustic（NA） solitary waves（SWs） propagating in a self-gravitating degenerate quantum plasma（SdQP）system（containing non-relativistically degenerate heavy and light nuclei,and non-/ultra-relativistically degenerate electrons） have been theoretically *** modified Korteweg–de Vries（m K-d V） equation has been derived for both planar and non-planar geometry by employing the reductive perturbation *** is shown that the NA SWs exist with positive（negative） electrostatic（self-gravitational） *** is also observed that the effects of non-/ultra-relativistically degenerate electron pressure,dynamics of non-relativistically light nuclei,spherical geometry,*** modify the basic features（e.g.,amplitude,width,speed,etc.） of the NA *** applications of our results,which are relevant to astrophysical compact objects,like white dwarfs and neutron stars,are briefly discussed.

关键词： self-gravitational potential solitary waves