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Thermal Plasma (thermal + plasma)
Kinds of Thermal Plasma Selected AbstractsIn-Flight-Melted Soda-Lime-Silica Glass by RF Induction Thermal PlasmaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Fuji Funabiki Granulated raw materials with a particle size of 20,80 ,m were prepared from a slurry of Na2CO3, CaCO3, and SiO2 (quartz) by the spray-dry method, and injected with carrier gas into a radio-frequency induction thermal plasma. Spherical particles 5,60 ,m in size were obtained and analyzed. Thermo-gravimetric analysis and X-ray diffraction analysis showed that during the short flight of the order of milliseconds, all carbonates were decomposed and >95% quartz was reacted into a noncrystalline state. Glass transition was clearly observed by differential thermal analysis. Increase of the carrier gas from 3 to 6 L/min led to a decrease in the volatilization ratio of Na2O from 46% to 18% with a slight decrease of the reaction ratio of quartz in trade balance. Electron probe microanalysis showed that the volatilization could be attributed to an excess heating of small particles <30 ,m, and suppression by the increase of carrier gas. [source] Energy Transfer Enables 1.53 ,m Photoluminescence from Erbium-Doped TiO2 Semiconductor Nanocrystals Synthesized by Ar/O2 Radio-Frequency Thermal PlasmaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Ji-Guang Li Highly crystalline, highly luminescent nanopowders of Er3+ -doped TiO2 have been successfully synthesized via one-step Ar/O2 radio-frequency thermal plasma processing. Energy transfer from the TiO2 host to Er3+ activators has been confirmed by combined means of UV-vis, excitation, and photoluminescence spectroscopies. As a consequence, bright photoluminescence at ,1.53 ,m was observed from the nanopowders either by directly exciting the Er3+ activator or by exciting the TiO2 host lattice. A comparative study shows that the nanopowder of the same system made via coprecipitation lacks the energy transfer. The plasma-generated nanopowders may thus find applications in optoelectronic devices. [source] Modulated Induction Thermal Plasmas , Fundamentals and Applications ,IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2009Yasunori Tanaka Member Abstract This paper reviews fundamentals and applications of modulated induction thermal plasmas that have been developed. The coil-current modulation of the order of several hundreds amperes allows one to make a large disturbance in high-pressure and high temperature plasmas, and also to control the temperature and radical density in thermal plasmas in time domain. Examples will be introduced on application of the modulated induction thermal plasma to surface modification, in which thermally and chemically nonequilibrium effects are essential in temperature and radical density fields. Finally, dynamic behaviors of an arbitrary-waveform modulated induction thermal plasma that has recently been developed were also introduced as a new type of modulated induction thermal plasmas. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Numerical simulation of thermal interaction between polymer and argon induction thermal plasmaELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2009Yoshitaka Takeuchi Abstract Influence of polymer powder injection into Ar thermal plasmas was investigated by numerical approaches. Thermal plasma,polymer solid coupling phenomena such as melting and evaporation were considered to study plasma-quenching effect of polymer injection. Dominant process for decay of plasma temperature was examined by changing thermodynamic parameters such as melting, boiling temperatures and their latent heats of solid and liquid polymers. As a result, thermodynamic properties of evaporated polymer vapor directly affect plasma-quenching phenomena more markedly than the properties of liquid and solid which influence plasma quenching efficiency through the amount of evaporation. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(1): 24,33, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10226 [source] Modulated Induction Thermal Plasmas , Fundamentals and Applications ,IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2009Yasunori Tanaka Member Abstract This paper reviews fundamentals and applications of modulated induction thermal plasmas that have been developed. The coil-current modulation of the order of several hundreds amperes allows one to make a large disturbance in high-pressure and high temperature plasmas, and also to control the temperature and radical density in thermal plasmas in time domain. Examples will be introduced on application of the modulated induction thermal plasma to surface modification, in which thermally and chemically nonequilibrium effects are essential in temperature and radical density fields. Finally, dynamic behaviors of an arbitrary-waveform modulated induction thermal plasma that has recently been developed were also introduced as a new type of modulated induction thermal plasmas. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] In-Flight-Melted Soda-Lime-Silica Glass by RF Induction Thermal PlasmaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Fuji Funabiki Granulated raw materials with a particle size of 20,80 ,m were prepared from a slurry of Na2CO3, CaCO3, and SiO2 (quartz) by the spray-dry method, and injected with carrier gas into a radio-frequency induction thermal plasma. Spherical particles 5,60 ,m in size were obtained and analyzed. Thermo-gravimetric analysis and X-ray diffraction analysis showed that during the short flight of the order of milliseconds, all carbonates were decomposed and >95% quartz was reacted into a noncrystalline state. Glass transition was clearly observed by differential thermal analysis. Increase of the carrier gas from 3 to 6 L/min led to a decrease in the volatilization ratio of Na2O from 46% to 18% with a slight decrease of the reaction ratio of quartz in trade balance. Electron probe microanalysis showed that the volatilization could be attributed to an excess heating of small particles <30 ,m, and suppression by the increase of carrier gas. [source] Spheroidization of Titanium Carbide Powders by Induction Thermal Plasma ProcessingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001Ya-Li Li Highly spherical particles of titanium carbide (TiC) have been produced by in-flight heat processing of irregularly shaped TiC powders in an aerosol reactor under argon-hydrogen and argon-helium induction thermal plasma. The spherical powders obtained by the plasma treatment consist of unagglomerated and uniform particles with mean diameters between 25 and 28.5 ,m, which is smaller than the original TiC particle mean diameters (29.5 ,m) because of partial evaporation of the particles during the plasma treatment. The spheroidization ratio of the treated TiC powders increases with the increase of hydrogen flow rate in plasma gases and the reduction of powder feeding carrier gas flow rate. Under certain processing conditions, the TiC powders have been completely spheroidized. The morphology and structure of individual spherical particles were examined and their formation mechanism was discussed based on calculation of heat transfer kinetics of the particles in the thermal plasma. [source] High-resolution observations of SN 2001gd in NGC 5033MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005M. A. Pérez-Torres ABSTRACT We report on 8.4-GHz very-long-baseline interferometry (VLBI) observations of SN 2001gd in the spiral galaxy NGC 5033 made on 2002 June 26 (2002.48) and 2003 April 8 (2003.27). We used the interferometric visibility data to estimate angular diameter sizes for the supernova by model fitting. Our data nominally suggest a relatively strong deceleration for the expansion of SN 2001gd, but we cannot dismiss the possibility of a free supernova expansion. From our VLBI observations on 2003 April 8, we inferred a minimum total energy in relativistic particles and magnetic fields in the supernova shell of Emin= (0.3,14) × 1047 erg, and a corresponding equipartition average magnetic field of Bmin= 50,350 mG. We also present multiwavelength Very Large Array (VLA) measurements of SN 2001gd made at our second VLBI epoch at frequencies of 1.4, 4.9, 8.4, 15.0, 22.5 and 43.3 GHz. The VLA data are well fitted by an optically thin, synchrotron spectrum (,=,1.0 ± 0.1; S,,,,), partially absorbed by thermal plasma. We obtain a supernova flux density of 1.02 ± 0.05 mJy at the observing frequency of 8.4 GHz for the second epoch, which results in an isotropic radio luminosity of (6.0 ± 0.3) × 1036 erg s,1 between 1.4 and 43.3 GHz, at an adopted distance of 13.1 Mpc. Finally, we report on an XMM,Newton X-ray detection of SN 2001gd on 2002 December 18. The supernova X-ray spectrum is consistent with optically thin emission from a soft component (associated with emission from the reverse shock) at a temperature of around 1 keV. The observed flux corresponds to an isotropic X-ray luminosity of LX= (1.4 ± 0.4) × 1039 erg s,1 in the 0.3,5 keV band. We suggest that both radio and X-ray observations of SN 2001gd indicate that a circumstellar interaction similar to that displayed by SN 1993J in M 81 is taking place. [source] Electron,cyclotron maser observable modesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2000A. Stupp We investigate wave amplification through the electron,cyclotron maser mechanism. We calculate absorption and emission coefficients without any approximations, also taking into account absorption by the ambient thermal plasma. A power-law energy distribution for the fast electrons is used, as indicated by X-ray and microwave observations. We develop a model for the saturation length and amplification ratio of the maser, scan a large parameter space and calculate the absorption and emission coefficients for every frequency and angle. Previous studies concluded that the unobservable Z mode dominates in the ,p,,B region, and that millisecond spikes are produced in the region ,p,B<0.25. We find that the observable O and X modes can produce emission in the 0.8<,p,B<2 region, which is expected at the footpoints of a flaring magnetic loop. The important criterion for observability is the saturation length and not the growth rate, as was assumed previously, and, even when the Z mode is the most strongly amplified, less strongly amplified O or X modes are still intense enough to be observed. The brightness temperature computed with our model for the saturation length is found to be of order 1016 K and higher. The emission is usually at a frequency of 2.06,B, and at angles of 30°,60° to the magnetic field. The rise time of the amplified emission to maximum is a few tenths of a millisecond to a few milliseconds, and the emission persists for as long as new fast electrons arrive in the maser region. [source] H2O maser and a plasma obscuring torus in the radio galaxy NGC 1052ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009S. Sawada-Satoh Abstract We present multi-frequency simultaneous VLBA observations at 15, 22 and 43 GHz towards the nucleus of the nearby radio galaxy NGC 1052. These three continuum images reveal a double-sided jet structure, whose relative intensity ratios imply that the jet axis is oriented close to the sky plane. The steeply rising spectra at 15,43 GHz at the inner edges of the jets strongly suggest that synchrotron emission is absorbed by foreground thermal plasma. We detected H2O maser emission in the velocity range of 1550,1850 km s,1, which is redshifted by 50,350 km s,1 with respect to the systemic velocity of NGC 1052. The redshifted maser gas appears projected against both sides of the jet, similar to the H I seen in absorption. The H2O maser gas is located where the free-free absorption opacity is large. This probably implies that the masers in NGC 1052 are associated with a circumnuclear torus or disk as in the nucleus of NGC 4258. Such circumnuclear structure can be the sense of accreting onto the central engine (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] X-rays from the HII Regions and Molecular Clouds near the Galactic CenterASTRONOMISCHE NACHRICHTEN, Issue S1 2003Katsuji Koyama Abstract We report measurements by Chandra of a variety of X-ray sources in the molecular clouds and HII regions of the Sgr B2, Arches, Quintuplet and the Galactic center clusters. Moderately bright X-ray sources are present in the Sgr B2, Quintuplet and the Galactic center clusters at the positions of ultra compact HII regions and bright infrared sources. Their X-ray spectra are fitted with models of a thin thermal plasma with 2,10 keV temperatures and luminosities of ,1032,33erg s,1. The X-ray properties are typical of those of high-mass young stellar objects or clusters of such objects. The Arches Cluster has three bright X-ray sources, at the positions of bright IR and radio stars, with X-ray luminosities of a few ×1033 erg s,1 each, which may indicate an unusual X-ray emission mechanism from high mass YSOs. A unique X-ray feature of molecular clouds and HII regions near the Galactic center is the presence of diffuse emission with a strong 6.4 keV line; in Sgr B2 this is attributable to the fluorescence of gas irradiated by external sources in the Galactic center, while the diffuse emission from Arches is puzzling. [source] Numerical simulation of thermal interaction between polymer and argon induction thermal plasmaELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2009Yoshitaka Takeuchi Abstract Influence of polymer powder injection into Ar thermal plasmas was investigated by numerical approaches. Thermal plasma,polymer solid coupling phenomena such as melting and evaporation were considered to study plasma-quenching effect of polymer injection. Dominant process for decay of plasma temperature was examined by changing thermodynamic parameters such as melting, boiling temperatures and their latent heats of solid and liquid polymers. As a result, thermodynamic properties of evaporated polymer vapor directly affect plasma-quenching phenomena more markedly than the properties of liquid and solid which influence plasma quenching efficiency through the amount of evaporation. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(1): 24,33, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10226 [source] Modulated Induction Thermal Plasmas , Fundamentals and Applications ,IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2009Yasunori Tanaka Member Abstract This paper reviews fundamentals and applications of modulated induction thermal plasmas that have been developed. The coil-current modulation of the order of several hundreds amperes allows one to make a large disturbance in high-pressure and high temperature plasmas, and also to control the temperature and radical density in thermal plasmas in time domain. Examples will be introduced on application of the modulated induction thermal plasma to surface modification, in which thermally and chemically nonequilibrium effects are essential in temperature and radical density fields. Finally, dynamic behaviors of an arbitrary-waveform modulated induction thermal plasma that has recently been developed were also introduced as a new type of modulated induction thermal plasmas. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] | |||||||||||||