RF and Microwave Plasma Deposition of Polymer Films: Effect of Frequency

1986 ◽  
Vol 68 ◽  
Author(s):  
R. Claude ◽  
M. Moisan ◽  
M. R. Wertheimer
Keyword(s):  
High Frequency ◽  
Microwave Plasma ◽  
Plasma Deposition ◽  
Argon Plasma ◽  
Plasma Technology ◽  
Low Frequencies ◽  
Plasma Polymers ◽  
Deposition Kinetics ◽  
Order Of Magnitude ◽  
Kinetics Of

AbstractThe surface wave (SW) plasma technology is used to investigate possible frequency effects in the deposition kinetics of plasma polymers over the range 100–915 MHz.Hydrocarbon and fluorocarbon monomers are excited by a SW produced argon plasma, at a total pressure of 50 mTorr, under various monomer flows.Using Yasuda's normalization procedure, we have so far been unable to distinguish frequency dependent deposition in this high frequency (HF) regime.However, the present data indicate substantially (an order of magnitude) higher deposition rates than those reported by Gazicki and Yasuda for low frequencies.

Microwave Plasma Technology of Pulverized Coal Combustion

2004 ◽  
Vol 61 (7-12) ◽  
pp. 650-662 ◽  
Author(s):  
Dmitry M. Vavriv ◽  
V. I. Kazantsev ◽  
P. M. Kanilo ◽  
N. I. Rasyuk ◽  
K. Schunemann ◽  
...  
Keyword(s):  
Coal Combustion ◽  
Microwave Plasma ◽  
Pulverized Coal ◽  
Pulverized Coal Combustion ◽  
Plasma Technology

scholarly journals Reduction Mechanism of Fine Hematite Ore Particles in Suspension

2021 ◽  
Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang
Keyword(s):  
Particle Size ◽  
Temperature Drop ◽  
Reduction Rate ◽  
Reduction Process ◽  
Reciprocal Relationship ◽  
Drop Tube ◽  
Surface Nucleation ◽  
Order Of Magnitude ◽  
Relationship Of ◽  
Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

scholarly journals Ice Coverage Induced by Depositing a Water Drop onto the Supercooled Substrate at Extreme Low Vapor Pressure

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 691
Author(s):  
Yugang Zhao ◽  
Zichao Zuo ◽  
Haibo Tang ◽  
Xin Zhang
Keyword(s):  
Vapor Pressure ◽  
Substrate Temperature ◽  
Water Drop ◽  
Industrial Processes ◽  
Aircraft Icing ◽  
Ice Coverage ◽  
Fundamental Understanding ◽  
Order Of Magnitude ◽  
The Impact ◽  
Kinetics Of

Icing/snowing/frosting is ubiquitous in nature and industrial processes, and the accretion of ice mostly leads to catastrophic consequences. The existing understanding of icing is still limited, particularly for aircraft icing, where direct observation of the freezing dynamics is inaccessible. In this work, we investigate experimentally the impact and freezing of a water drop onto the supercooled substrate at extremely low vapor pressure, to mimic an aircraft passing through clouds at a relatively high altitude, engendering icing upon collisions with pendant drops. Special attention is focused on the ice coverage induced by an impinging drop, from the perimeter pointing outward along the radial direction. We observed two freezing regimes: (I) spread-recoil-freeze at the substrate temperature of Ts = −15.4 ± 0.2 °C and (II) spread (incomplete)-freeze at the substrate temperature of Ts = −22.1 ± 0.2 °C. The ice coverage is approximately one order of magnitude larger than the frozen drop itself, and counterintuitively, larger supercooling yields smaller ice coverage in the range of interest. We attribute the variation of ice coverage to the kinetics of vapor diffusion in the two regimes. This fundamental understanding benefits the design of new anti-icing technologies for aircraft.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

Supercritical Fluid Deposition of Ruthenium Thin Films: A Kinetic Study

2007 ◽  
Vol 992 ◽  
Author(s):  
Christos F. Karanikas ◽  
James J. Watkins
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Deposition Temperature ◽  
Zero Order ◽  
Measurable Effect ◽  
Deposition Rates ◽  
Reaction Pressure ◽  
Deposition Kinetics ◽  
First Order ◽  
Kinetics Of

AbstractThe kinetics of the deposition of ruthenium thin films from the hydrogen assisted reduction of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(1,5-cyclooctadiene)ruthenium(II), [Ru(tmhd)2cod], in supercritical carbon dioxide was studied in order to develop a rate expression for the growth rate as well as to determine a mechanism for the process. The deposition temperature was varied from 240°C to 280°C and the apparent activation energy was 45.3 kJ/mol. Deposition rates up to 30 nm/min were attained. The deposition rate dependence on precursor concentrations between 0 and 0.2 wt. % was studied at 260°C with excess hydrogen and revealed first order deposition kinetics with respect to precursor at concentrations lower then 0.06 wt. % and zero order dependence at concentrations above 0.06 wt. %. The effect of reaction pressure on the growth rate was studied at a constant reaction temperature of 260°C and pressures between 159 bar to 200 bar and found to have no measurable effect on the growth rate.

Effective coffision frequency and electron temperature in a weakly ionized argon plasma

1980 ◽  
Vol 23 (2) ◽  
pp. 271-282
Author(s):  
C. P. Schneider
Keyword(s):  
Electron Temperature ◽  
High Frequency ◽  
Collision Frequency ◽  
Argon Plasma ◽  
Angular Frequency ◽  
Weak Electric Field ◽  
Hard Sphere Model ◽  
Plasma Conductivity ◽  
Gas Plasma ◽  
Weakly Ionized

Herein is described a calculation of the effective coffision frequency νeffof a low- density, shock-heated argon plasma under the influence of a weak electric field which oscillates harmonically with angular frequency ω. It is shown that, for the high frequency case ω >whereis the collision frequency in a Maxwellian gas plasma, one has νeff⋍ 2, provided that the imaginary part of the argon plasma conductivity is negligibly small in comparison to the real part. The influence of the theoretical model used to calculate νeffon the values of the electron temperatureTederived from measurements is compared with the results obtained in a data reduction for which the hard-sphere model for particle encounters was utilized.

Kinetics of the Electronic States of Molecular Nitrogen in a Recombining Air/Argon Plasma

2022 ◽  
Author(s):  
Ulysse Dubuet ◽  
Pierre Mariotto ◽  
Christophe O. Laux ◽  
Marie-Yvonne Perrin
Keyword(s):  
Molecular Nitrogen ◽  
Argon Plasma ◽  
Electronic States ◽  
Kinetics Of

LOW-TEMPERATURE ION-PLASMA DEPOSITION TECHNOLOGY OF NANOSTRUCTURED FILMS OF ALUMINUM AND BORON NITRIDES

2021 ◽  
Vol 56 ◽  
pp. 97-107
Author(s):  
M. S. Zayats ◽  
Keyword(s):  
Dielectric Properties ◽  
Low Temperature ◽  
Magnetron Sputtering ◽  
High Frequency ◽  
Plasma Deposition ◽  
Heating Temperature ◽  
Substrate Heating ◽  
Ion Plasma ◽  
Technological Cycle ◽  
Physical And Chemical

A low-temperature (substrate heating temperature up to 400 °C) ion-plasma technology for the formation of nanostructured AlN and BN films by the method of high-frequency reactive magnetron sputtering of the corresponding targets has been developed (the modernized installation "Cathode-1M"), which has in its technological cycle the means of physical and chemical modification, which allow to purposefully control the phase composition, surface morphology, size and texture of nanocrystalline films. The possibility of using the method of high-frequency magnetron sputtering for deposition of transparent hexagonal BN films in the nanoscale state on quartz and silicon substrates is shown. Atomic force microscopy (AFM) has shown that AlN films can have an amorphous or polycrystalline surface with grain sizes of approximately 20-100 nm, with the height of the nanoparticles varying from 3 to 10 nm and the degree of surface roughness from 1 to 10 nm. It was found that the dielectric penetration of polycrystalline AlN films decreases from 10 to 3.5 at increased frequencies from 25 Hz to 1 MHz, and the peak tangent of the dielectric loss angle reaches 0.2 at 10 kHz. Such features indicate the existence of spontaneous polarization of dipoles in the obtained AlN films. Interest in dielectric properties in AlN / Si structures it is also due to the fact that there are point defects, such as nitrogen vacancies and silicon atoms, which diffuse from the silicon substrate during synthesis and play an important role in the dielectric properties of AlN during the formation of dipoles. The technology makes it possible, in a single technological cycle, to produce multilayer structures modified for specific functional tasks with specified characteristics necessary for the manufacture of modern electronics, optoelectronics and sensorics devices. It should also be noted that the technology of magnetron sputtering (installation "Cathode-1M") is highly productive, energetically efficient and environmentally friendly in comparison with other known technologies for creating semiconductor structures and allows them to be obtained with minimal changes in the technological cycle.

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