Generation of microwave plasma under high pressure and fabrication of ultrafine carbon particles

1998 ◽  
Vol 13 (6) ◽  
pp. 1724-1727 ◽  
Author(s):  
H. Yagi ◽  
T. Ide ◽  
H. Toyota ◽  
Y. Mori
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Diffraction Analysis ◽  
Microwave Plasma ◽  
Plasma Generator ◽  
Two Stage ◽  
Carbon Particles ◽  
Helium Gas ◽  
In Series ◽  
Fine Carbon

A microwave plasma generator, which functions under high pressure, has been developed and used in the fabrication of fine carbon particles. The plasma generator is a two-stage-type resonator, which consists of rectangular and semi-cylindrical-type resonators which are coupled in series for torching plasma and keeping it stable under high pressure. The plasma can be torched in helium gas at 3 × 106 Pa by tuning the dimensions of apparatus elements. Fine carbon particles of ~50 nm are obtained using a mixture of helium and methane gas. The particles are found to be crystalline from the results of transparent electron microscopy and diffraction analysis.

Preparation of Nanocomposite Particles from Typha angustifolia and Egg Shells

2014 ◽  
Vol 608 ◽  
pp. 68-72 ◽  
Author(s):  
Apiluck Eiad-Ua ◽  
Koonyad Insuang ◽  
Supattra Changsuwan ◽  
Nawin Viriya-Empikul
Keyword(s):  
Electron Microscopy ◽  
Planetary Mill ◽  
Argon Atmosphere ◽  
Typha Angustifolia ◽  
Carbon Particles ◽  
Air Atmosphere ◽  
Egg Shells ◽  
Composite Product ◽  
Fine Carbon ◽  
Scanning Electron

Nanocomposite Paticles have been successfully synthesized from Typha Angustifolia and Egg Shells via 3 steps synthesis; hydrothermal, pyrolysis and/or ball milling techniques, respectively. Typha Angustifolia was subjected to produce fine carbon particles by two stage processes of hydrothermal (at 200 °C for 4 h) and carbonization technique (under Argon atmosphere at 700 °C for 2 h) while the egg shells were convert to white powder (calcium oxide) by calcining under air atmosphere at 900 °C for 4 h. The samples have been characterized by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) to investigate the morphology and surface function, respectively. The experimental results revealed that the planetary mill have effect on the composites between carbon and calcium. Calcium was deposited on the surface of carbon material. Moreover, when the calcium was increased leading to higher performance of milling (i.e. the smaller composite product was observed).

Two-Stage Turbocharger Modeling for Engine Control and Estimation

2007 ◽  
Author(s):  
Yong Shu ◽  
Michiel van Nieuwstadt
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Model Parameters ◽  
Total Efficiency ◽  
Outlet Temperature ◽  
Two Stage ◽  
Modeling And Control ◽  
Charging System ◽  
In Series ◽  
Pressure Compressor

The increasingly stringent emissions regulations and needs for higher power density for both turbo-diesel passenger vehicle and commercial vehicles have demanded significant alterations to the basic architecture of turbochargers. An attractive option for providing a high-boost system is the use of two-stage turbocharger which consists of two different size turbochargers connected in series that may or may not utilize bypass regulation. The exhaust mass flow is expanded by the high pressure turbine to the low pressure turbine, and on the other side the air flow is compressed through the low pressure compressor to the high pressure compressor. This increases the complexity of the air-charging system and requires new methodologies for modeling and control. A two-stage turbocharger model is presented in this paper. The total efficiency of the two-stage compressor, which poses the biggest problem in two-stage turbocharger modeling, was derived based on a second law analysis. A new parameter, compressor temperature ratio, was introduced as a linkage between the two stage compressors and also used to predict the two-stage compressor outlet temperature. Extrapolation to lower turbocharger speeds and compressor flow rates by using curve fitting methods was also discussed. The model for a two-stage turbine with a bypass valve is derived in the same way. Engine dynamometer tests have been performed to identify the model parameters and to validate the model structure. The test results show a good agreement between the model predictions and test data. In conclusion, this two stage turbocharger model is suitable for turbocharger control design and the estimation of some key turbocharger parameters.

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Computers and diffraction analysis

1989 ◽  
Vol 47 ◽  
pp. 44-45
Author(s):  
J. A. Eades
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Diffraction Analysis ◽  
Electron Diffraction Analysis ◽  
Image Simulation ◽  
Correct Interpretation ◽  
High Profile ◽  
High Resolution Images ◽  
Image Simulations

For well over two decades computers have played an important role in electron microscopy; they now pervade the whole field - as indeed they do in so many other aspects of our lives. The initial use of computers was mainly for large (as it seemed then) off-line calculations for image simulations; for example, of dislocation images.Image simulation has continued to be one of the most notable uses of computers particularly since it is essential to the correct interpretation of high resolution images. In microanalysis, too, the computer has had a rather high profile. In this case because it has been a necessary part of the equipment delivered by manufacturers. By contrast the use of computers for electron diffraction analysis has been slow to prominence. This is not to say that there has been no activity, quite the contrary; however it has not had such a great impact on the field.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

Scattering of Electrons at High - Pressure and Restoration of Image Contrast in High Pressure Scanning Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 384-385
Author(s):  
J. S. Shah ◽  
R. Durkin ◽  
A. N. Farley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Cross Sections ◽  
Single Scattering ◽  
Image Contrast ◽  
Experimental Scheme ◽  
Medium Resolution ◽  
Scattering Approximation ◽  
Scanning Electron

It is now possible to perform High Pressure Scanning Electron Microscopy (HPSEM) in the range 10 to 2000 Pa. Here the effect of scattering on resolution has been evaluated by calculating the profile of the beam in high pressure and assessing its effect on the image contrast . An experimental scheme is presented to show that the effect of the primary beam ionization is to reduce image contrast but this effect can be eliminated by a novel use of specimen current detection in the presence of an electric field. The mechanism of image enhancement is discussed in terms of collection of additional carriers generated by the emissive components.High Pressure SEM (HPSEM) instrumentation is establishing itself as commercially viable. There are now a number of manufacturers, such as JEOL, ABT, ESCAN, DEBEN RESEARCH, selling microscopes and accessories for HPSEM. This is because high pressure techniques have begun to yield high quality micrographs at medium resolution.To study the effect of scattering on the incident electron beam, its profile - in a high pressure environment - was evaluated by calculating the elastic and inelastic scattering cross sections for nitrogen in the energy range 5-25 keV. To assess the effect of the scattered beam on the image contrast, the modification of a sharp step contrast function due to scattering was calculated by single scattering approximation and experimentally confirmed for a 20kV accelerated beam.

Effect of high pressure-temperature on silicon layered structures as determined by X-ray diffraction and electron microscopy

2004 ◽  
Vol 27 (1-3) ◽  
pp. 415-418
Author(s):  
J. Bak-Misiuk ◽  
A. Misiuk ◽  
J. Ratajczak ◽  
A. Shalimov ◽  
I. Antonova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Layered Structures ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals The Assessment of Carbon Dioxide Dissociation Using a Single-Mode Microwave Plasma Generator

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1558 ◽  
Author(s):  
George Mogildea ◽  
Marian Mogildea ◽  
Cristina Popa ◽  
Gabriel Chiritoi
Keyword(s):  
Carbon Dioxide ◽  
Microwave Plasma ◽  
Focal Point ◽  
Single Mode ◽  
Plasma Generator ◽  
High Energy ◽  
High Electron ◽  
Space Applications ◽  
Plasma Characterization ◽  
Co2 Atmosphere

This paper focuses on the dissociation of carbon dioxide (CO2) following the absorption processes of microwave radiation by noncontact metal wire (tungsten). Using a microwave plasma generator (MPG) with a single-mode cavity, we conducted an interaction of microwaves with a noncontact electrode in a CO2 atmosphere. High energy levels of electromagnetic radiation are generated in the focal point of the MPG’s cylindrical cavity. The metal wires are vaporized and ionized from this area, subsequently affecting the dissociation of CO2. The CO2 dissociation is highlighted through plasma characterization and carbon monoxide (CO) quantity determination. For plasma characterization, we used an optical emission spectroscopy method (OES), and for CO quantity determination, we used a gas analyzer instrument. Using an MPG in the CO2 atmosphere, we obtained a high electron temperature of the plasma and a strong dissociation of CO2. After 20 s of the interaction between microwaves and noncontact electrodes, the quantity of CO increased from 3 ppm to 1377 ppm (0.13% CO). This method can be used in space applications to dissociate CO2 and refresh the atmosphere of closed spaces.

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