Rapid industrialization and urbanization in developing countries has led to an increase in air pollution, along a similar trajectory to that previously experienced by the developed nations. In China, particulate pollution is a serious environmental problem that is influencing air quality, regional and global climates, and human health. In response to the extremely severe and persistent haze pollution experienced by about 800 million people during the first quarter of 2013 (refs 4, 5), the Chinese State Council announced its aim to reduce concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 micrometres) by up to 25 per cent relative to 2012 levels by 2017 (ref. 6). Such efforts however require elucidation of the factors governing the abundance and composition of PM2.5, which remain poorly constrained in China. Here we combine a comprehensive set of novel and state-of-the-art offline analytical approaches and statistical techniques to investigate the chemical nature and sources of particulate matter at urban locations in Beijing, Shanghai, Guangzhou and Xi'an during January 2013. We find that the severe haze pollution event was driven to a large extent by secondary aerosol formation, which contributed 30-77 per cent and 44-71 per cent (average for all four cities) of PM2.5 and of organic aerosol, respectively. On average, the contribution of secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA) are found to be of similar importance (SOA/SIA ratios range from 0.6 to 1.4). Our results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from, for example, fossil fuel combustion and biomass burning is likely to be important for controlling China's PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution.

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High secondary aerosol contribution to particulate pollution during haze events in China

Inertial confinement fusion (ICF) is an approach to fusion that relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which inertial confinement is sufficient for efficient thermonuclear burn, a capsule (generally a spherical shell) containing thermonuclear fuel is compressed in an implosion process to conditions of high density and temperature. ICF capsules rely on either electron conduction (direct drive) or x rays (indirect drive) for energy transport to drive an implosion. In direct drive, the laser beams (or charged particle beams) are aimed directly at a target. The laser energy is transferred to electrons by means of inverse bremsstrahlung or a variety of plasma collective processes. In indirect drive, the driver energy (from laser beams or ion beams) is first absorbed in a high‐Z enclosure (a hohlraum), which surrounds the capsule. The material heated by the driver emits x rays, which drive the capsule implosion. For optimally designed targets, 70%–80% of the d...

/pdf/development-of-the-indirect-drive-approach-to-inertial-314a4yq250.pdf

Development of the indirect‐drive approach to inertial confinement fusion and the target physics basis for ignition and gain

Dust -acoustic waves in dusty plasmas

With its roots in kinetic theory and the cellular automaton concept, the lattice-Boltzmann (LB) equation can be used to obtain continuum flow quantities from simple and local update rules based on particle interactions. The simplicity of formulation and its versatility explain the rapid expansion of the LB method to applications in complex and multiscale flows. We review many significant developments over the past decade with specific examples. Some of the most active developments include the entropic LB method and the application of the LB method to turbulent flow, multiphase flow, and deformable particle and fiber suspensions. Hybrid methods based on the combination of the Eulerian lattice with a Lagrangian grid system for the simulation of moving deformable boundaries show promise for more efficient applications to a broader class of problems. We also discuss higherorder boundary conditions and the simulation of microchannel flow with finite Knudsen number. Additionally, the remarkable scalability of the LB method for parallel processing is shown with examples. Teraflop simulations with the LB method are routine, and there is no doubt that this method will be one of the first candidates for petaflop computational fluid dynamics in the near future.

Lattice-Boltzmann Method for Complex Flows

Note from the Series Editor. Foreword. Preface. Acknowledgments. Chapter 1: Introduction. 1.1 Electric Propulsion Background. 1.2 Electric Thruster Types. 1.3 Ion Thruster Geometry. 1.4 Hall Thruster Geometry. 1.5 Beam/Plume Characteristics. References. Chapter 2: Thruster Principles. 2.1 The Rocket Equation. 2.2 Force Transfer in Ion and Hall Thrusters. 2.3 Thrust. 2.4 Specific Impulse. 2.5 Thruster Efficiency. 2.6 Power Dissipation. 2.7 Neutral Densities and Ingestion in Electric Thrusters. References. Problems. Chapter 3: Basic Plasma Physics. 3.1 Introduction. 3.2 Maxwell's Equations. 3.3 Single Particle Motions. 3.4 particle Energies and Velocities. 3.5 Plasma as a Fluid. 3.6 Diffusion in Partially Ionized Gases. 3.7 Sheaths at the Boundaries of Plasmas. References. Problems. Chapter 4: Ion Thruster Plasma Generators. 4.1 Introduction. 4.2 Idealized Ion Thruster Plasma Generator. 4.3 DC Discharge Ion Thruster. 4.4 Kaufman Ion Thrusters. 4.5 rf Ion Thrusters. 4.6 Microwave Ion Thrusters. 4.7 2-D Computer Models of the Ion Thruster Discharge Chamber. References. Problems. Chapter 5: Ion Thruster Accelerator Grids. 5.1 Grid Configurations. 5.2 Ion Accelerator Basics. 5.3 Ion Optics. 5.4 Electron Backstreaming. 5.5 High-Voltage Considerations. 5.6 Ion Accelerator Grid Life. References. Problems. Chapter 6: Hollow Cathodes. 6.1 Introduction. 6.2 Cathode Configurations. 6.3 Thermionic Electron Emitter Characteristics. 6.4 Insert Region Plasma. 6.5 Orifice Region Plasma. 6.6 Hollow cathode Thermal Models. 6.7 Cathode Plume-Region Plasma. 6.8 Hollow Cathode Life. 6.9 Keeper Wear and Life. 6.10 Hollow Cathode Operation. References. Problems. Chapter 7: Hall Thrusters. 7.1 Introduction. 7.2 Thruster Operating Principles and Scaling. 7.3 Hall Thruster Performance Models. 7.4 Channel Physics and Numerical Modeling. 7.5 Hall Thruster Life. References. Problems. Chapter 8: Ion and Hall Thruster Plumes. 8.1 Introduction. 8.2 Plume Physics. 8.3 Plume Models. 8.4 Spacecraft Interactions. 8.5 Interactions with Payloads. References. Problems. Chapter 9: Flight Ion and Hall Thrusters. 9.1 Introduction. 9.2 Ion Thrusters. 9.3 Hall Thrusters. References. Appendices. A: Nomenclature. B: Gas Flow Unit Conversions and Cathode Pressure Estimates. C: Energy Loss by Electrons. D: Ionization and Excitation Cross Sections for Xenon. E: Ionization and Excitation Reaction Rates for Xenon in Maxwellian Plasmas. F: Electron Relaxation and Thermalization Times. G: Clausing Factor Monte Carlo Calculation. Index..

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Fundamentals of electric propulsion : ion and Hall thrusters

1. Introduction.- 2. Single-Particle Motions.- 3. Plasmas as Fluids.- 4. Waves in Plasmas.- 5. Diffusion and Resistivity.- 6. Equilibrium and Stability.- 7. Kinetic Theory.- 8. Nonlinear Effects.- Appendices.- Appendix A. Units, Constants and Formulas, Vector Relations.- Appendix B. Theory of Waves in a Cold Uniform Plasma.- Appendix C. Sample Three-Hour Final Exam.- Appendix D. Answers to Some Problems.- Index to Problems.

Introduction to Plasma Physics and Controlled Fusion

1. Introduction.- Occurrence of Plasmas in Nature.- Definition of Plasma.- Concept of Temperature.- Debye Shielding.- The Plasma Parameter.- Criteria for Plasmas.- Applications of Plasma Physics.- 2. Single-Particle Motions.- Uniform E and B Field.- Nonuniform B Field.- Nonuniform E Field.- TimeVarying E Field.- Time-Varying B Field.- Summary of Guiding Center Drifts.- Adiabatic Invariants.- 3. Plasmas as Fluids.- Relation of Plasma Physics to Ordinary Electromagnetics.- The Fluid Equation of Motion.- Fluid Drifts Perpendicular to B.- Fluid Drifts Parallel to B.- The Plasma Approximation.- 4. Waves in Plasmas.- Representation of Waves.- Group Velocity.- Plasma Oscillations.- Electron Plasma Waves.- Sound Waves.- Ion Waves.- Validity of the Plasma Approximation.- Comparison of Ion and Electron Waves.- Electrostatic Electron Oscillations Perpendicular to B.- Electrostatic Ion Waves Perpendicular to B.- The Lower Hybrid Frequency.- Electromagnetic Waves with B0 =.- Experimental Applications.- Electromagnetic Waves Perpendicular to B0.- Cutoffs and Resonances.- Electromagnetic Waves Parallel to B0.- Experimental Consequences.- Hydromagnetic Wave.- Magnetosonic Waves.- Summary of Elementary Plasma Waves.- The CMA Diagram.- 5. Diffusion and Resistivity.- Diffusion and Mobility in Weakly Ionized Gases.- Decay of a Plasma by Diffusion.- Steady State Solutions.- Recombination.- Diffusion Across a Magnetic Field.- Collisions in Fully Ionized Plasmas.- The Single-Fluid MHD Equations.- Diffusion in Fully Ionized Plasmas.- Solutions of the Diffusion Equation.- Bohm Diffusion and Neoclassical Diffusion.- 6. Equilibrium and Stability.- Introductio.- Hydromagnetic Equilibrium.- The Concept of ss.- Diffusion of Magnetic Field into a Plasma.- Classification of Instabilities.- Two-Stream Instability.- The "Gravitational" Instability.- Resistive Drift Waves.- 7. Introduction to Kinetic Theory.- The Meaning off(v).- Equations of Kinetic Theory.- Derivation of the Fluid Equations.- Plasma Oscillations and Landau Damping.- The Meaning of Landau Damping.- A Physical Derivation of Landau Damping.- BGK and Van Kampen Modes.- Experimental Verification.- Ion Landau Damping.- 8. Nonlinear Effects.- Sheaths.- Ion Acoustic Shock Waves.- The Ponderomotive Force.- Parametric Instabilities.- Plasma Echoes.- Nonlinear Landau Damping.- 9. Introduction to Controlled Fusion.- The Problem of Controlled Fusion.- Magnetic Confinement: Toruses.- Mirrors.- Pinches.- Laser-Fusion.- Plasma Heating.- Fusion Technology.- Summary.- Units.- Useful Constants and Formulas.- Useful Vector Relations.

Introduction to Plasma Physics

1. Introduction.- Occurrence of Plasmas in Nature.- Definition of Plasma.- Concept of Temperature.- Debye Shielding.- The Plasma Parameter.- Criteria for Plasmas.- Applications of Plasma Physics.- 2. Single-Particle Motions.- Uniform E and B Field.- Nonuniform B Field.- Nonuniform E Field.- TimeVarying E Field.- Time-Varying B Field.- Summary of Guiding Center Drifts.- Adiabatic Invariants.- 3. Plasmas as Fluids.- Relation of Plasma Physics to Ordinary Electromagnetics.- The Fluid Equation of Motion.- Fluid Drifts Perpendicular to B.- Fluid Drifts Parallel to B.- The Plasma Approximation.- 4. Waves in Plasmas.- Representation of Waves.- Group Velocity.- Plasma Oscillations.- Electron Plasma Waves.- Sound Waves.- Ion Waves.- Validity of the Plasma Approximation.- Comparison of Ion and Electron Waves.- Electrostatic Electron Oscillations Perpendicular to B.- Electrostatic Ion Waves Perpendicular to B.- The Lower Hybrid Frequency.- Electromagnetic Waves with B0 =.- Experimental Applications.- Electromagnetic Waves Perpendicular to B0.- Cutoffs and Resonances.- Electromagnetic Waves Parallel to B0.- Experimental Consequences.- Hydromagnetic Wave.- Magnetosonic Waves.- Summary of Elementary Plasma Waves.- The CMA Diagram.- 5. Diffusion and Resistivity.- Diffusion and Mobility in Weakly Ionized Gases.- Decay of a Plasma by Diffusion.- Steady State Solutions.- Recombination.- Diffusion Across a Magnetic Field.- Collisions in Fully Ionized Plasmas.- The Single-Fluid MHD Equations.- Diffusion in Fully Ionized Plasmas.- Solutions of the Diffusion Equation.- Bohm Diffusion and Neoclassical Diffusion.- 6. Equilibrium and Stability.- Introductio.- Hydromagnetic Equilibrium.- The Concept of ss.- Diffusion of Magnetic Field into a Plasma.- Classification of Instabilities.- Two-Stream Instability.- The \"Gravitational\" Instability.- Resistive Drift Waves.- 7. Introduction to Kinetic Theory.- The Meaning off(v).- Equations of Kinetic Theory.- Derivation of the Fluid Equations.- Plasma Oscillations and Landau Damping.- The Meaning of Landau Damping.- A Physical Derivation of Landau Damping.- BGK and Van Kampen Modes.- Experimental Verification.- Ion Landau Damping.- 8. Nonlinear Effects.- Sheaths.- Ion Acoustic Shock Waves.- The Ponderomotive Force.- Parametric Instabilities.- Plasma Echoes.- Nonlinear Landau Damping.- 9. Introduction to Controlled Fusion.- The Problem of Controlled Fusion.- Magnetic Confinement: Toruses.- Mirrors.- Pinches.- Laser-Fusion.- Plasma Heating.- Fusion Technology.- Summary.- Units.- Useful Constants and Formulas.- Useful Vector Relations.

The dispersion relation for helicon waves in a uniform, bounded plasma is derived with both collisional and Landau damping. It is shown that the latter can explain the very high absorption efficiency of helicon waves in plasma sources and can lead to plasma generators with a controlled primary electron energy. The wave pattern and other features of helicon waves are pointed out.

https://iopscience.iop.org/article/10.1088/0741-3335/33/4/006/pdf

Plasma ionization by helicon waves

First observed in gaseous plasmas in the early 1960s, helicon discharges lay like a sleeping giant until they emerged in the 1980s, when their usefulness as efficient plasma sources for processing microelectronic circuits for the burgeoning semiconductor industry became recognized. Research on helicons spread to many countries; new, challenging, unexpected problems arose, and these have spawned solutions and novel insights into the physical mechanisms in magnetized radio-frequency discharges. Among the most baffling puzzles were the reason for the high ionization efficiency of helicon discharges and the dominance of the right-hand polarized mode over the left-hand one. The most recent results indicate that a nonobvious resolution of these problems is at hand.

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Francis F. Chen

Papers

Introduction to Plasma Physics and Controlled Fusion

Introduction to Plasma Physics

Introduction to Plasma Physics

Plasma ionization by helicon waves

Helicons-the past decade