Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

The application of mass spectrometric techniques to the realtime measurement and characterization of aerosols represents a significant advance in the field of atmospheric science. This review focuses on the aerosol mass spectrometer (AMS), an instrument designed and developed at Aerodyne Research, Inc. (ARI) that is the most widely used thermal vaporization AMS. The AMS uses aerodynamic lens inlet technology together with thermal vaporization and electron-impact mass spectrometry to measure the real-time non-refractory (NR) chemical speciation and mass loading as a function of particle size of fine aerosol particles with aerodynamic diameters between similar to 50 and 1,000 nm. The original AMS utilizes a quadrupole mass spectrometer (Q) with electron impact (EI) ionization and produces ensemble average data of particle properties. Later versions employ time-of-flight (ToF) mass spectrometers and can produce full mass spectral data for single particles. This manuscript presents a detailed discussion of the strengths and limitations of the AMS measurement approach and reviews how the measurements are used to characterize particle properties. Results from selected laboratory experiments and field measurement campaigns are also presented to highlight the different applications of this instrument. Recent instrumental developments, such as the incorporation of softer ionization techniques (vacuum ultraviolet (VUV) photo-ionization, Li(+) ion, and electron attachment) and high-resolution ToF mass spectrometers, that yield more detailed information about the organic aerosol component are also described. (c) 2007 Wiley Periodicals, Inc.

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Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometer

Atmospheric-pressure plasmas are used in a variety of materials processes. Traditional sources include transferred arcs, plasma torches, corona discharges, and dielectric barrier discharges. In arcs and torches, the electron and neutral temperatures exceed 3000/spl deg/C and the densities of charge species range from 10/sup 16/-10/sup 19/ cm/sup -3/. Due to the high gas temperature, these plasmas are used primarily in metallurgy. Corona and dielectric barrier discharges produce nonequilibrium plasmas with gas temperatures between 50-400/spl deg/C and densities of charged species typical of weakly ionized gases. However, since these discharges are nonuniform, their use in materials processing is limited. Recently, an atmospheric-pressure plasma jet has been developed, which exhibits many characteristics of a conventional, low-pressure glow discharge. In the jet, the gas temperature ranges from 25-200/spl deg/C, charged-particle densities are 10/sup 11/-10/sup 12/ cm/sup -3/, and reactive species are present in high concentrations, i.e., 10-100 ppm. Since this source may be scaled to treat large areas, it could be used in applications which have been restricted to vacuum. In this paper, the physics and chemistry of the plasma jet and other atmospheric-pressure sources are reviewed.

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The atmospheric-pressure plasma jet: a review and comparison to other plasma sources

Atmospheric pressure plasmas: A review

A commercial torch has been modified to introduce an additional anti-vortex and shroud gas flow to counter the detrimental effects brought about by the vortex plasma gas flow which is used to stabilize the cathode arc attachment and to increase the anode life. Deposition efficiency and coating quality are used as criteria to judge the modified versus the nonmodified torch. High-speed videography and computerized image analysis systems are used to determine the particle trajectories, velocities, and the plasma jet geometry. The results show that the additional anti-vortex and shroud gas flow to the torch can keep the particles closer to the torch axis and reduce the amount of entrainment of cold air into the plasma jet. The consequence is that deposition efficiency and coating quality are substantially improved.

Improvement of plasma spraying efficiency and coating quality

Described herein are batches of nanoscale phosphor particles having an average particle size of less than about 200 nm and an average internal quantum efficiency of at least 40%. The batches of nanoscale phosphor particles can be substantially free of impurities. Also described herein are methods of manufacturing the nanoscale phosphor particles by passing phosphor particles through a reactive field to thereby dissociate them into elements and then synthesizing nanoscale phosphor particles by nucleating the elements and quenching the resulting particles.

Nanoscale phosphor particles with high quantum efficiency and method for synthesizing the same

The synthesis of silicon nanowires that are densely coated with silicon nanoparticles is reported. These structures were produced in a two-step process, using a method known as hypersonic plasma particle deposition. In the first step, a Ti–Si nanoparticle film was deposited. In the second step the Ti-source was switched off, and nanoparticle-coated nanowires grew under the simultaneous action of Si vapor deposition and bombardment by Si nanoparticles. Total process time, including both steps, equaled 5 min, and resulted in formation of a dense network of randomly oriented nanowires covering1.5 cm2 of substrate area. The nanowires are composed of single-crystal Si. The diameters of the nanowires vary over the range 100–800 nm. Each nanowire has a crystalline TiSi2 catalyst particle, believed to have been solid during nanowire growth, at its tip.

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Nanoparticle-Coated Silicon Nanowires

Boron carbide thin film deposition using supersonic plasma jet with substrate biasing

A theoretical model describing the influence of the arc condition and the cathode material and geometry on arc cathode erosion has been formulated. To arrive at a self-consistent description for the entire arc cathode attachment region, a realistic, one-dimensional sheath model is used. This sheath model is supplemented by an integral energy balance of the ionization zone between the sheath and the arc, and by a differential energy balance of the cathode. For the case of a tungsten cathode, it is shown that arc constriction has a strong effect on the current density at the cathode spot but little influence on the cathode temperature. Heat conduction within the cathode and radiation from the cathode surface control the energy transport from the cathode spot at low currents, and dissipation by thermionic electron release dominates at high currents. For high-current applications, erosion can be minimized by using a cathode material with a low vapor pressure. For these conditions, the thermal design of the cathode plays a secondary role. For low currents, the erosion will be determined by the thermal characteristics of the cathode material. >

Joachim Heberlein

Papers

Improvement of plasma spraying efficiency and coating quality

Nanoscale phosphor particles with high quantum efficiency and method for synthesizing the same

Nanoparticle-Coated Silicon Nanowires

Boron carbide thin film deposition using supersonic plasma jet with substrate biasing

Theoretical study of factors influencing arc erosion of cathode