Photo-ionization and the electrical breakdown of gases

1953 ◽  
Vol 218 (1133) ◽  
pp. 206-223 ◽  
Keyword(s):  
Cross Sections ◽  
Electrical Breakdown ◽  
Secondary Emission ◽  
Ionization Process ◽  
Predominant Role ◽  
Quantitative Investigation ◽  
Ionization Coefficients ◽  
Photo Ionization ◽  
Molecule Interaction

A quantitative theoretical investigation is made of the role of photo-ionization of the gas in the development of ionization currents in gases under uniform fields. Using published values of the relevant absorption coefficients and atomic cross-sections, the theory is applied to the case of air, and the results then compared with those previously obtained experimentally, It is shown that photo-ionization can lead to electrical breakdown only under certain restricted conditions, which relate the ionization coefficients and atomic cross-sections for photon-molecule interaction; these restrictions are such that there must be considerable penetration of the gas by ionizing photons, and in many cases a high proportion of all the photons thus reach the cathode. It is also found that the theoretical curve for the growth of current, obtained on the assumption that photo-ionization is the only operative secondary ionization process, has the same general form as the growth curve based on the other secondary processes, e. g. secondary emission from the cathode; there are, however, significant differences in detail. This quantitative investigation supports the view that photo-ionization does not play a predominant role as a secondary ionization process leading to the electrical breakdown of air at values of p x d ~ 760 cm mm Hg in uniform fields.

Predominant role of the chorda tympani nerve in the maintenance of the taste pores: the influence of gustatory denervation in ear surgery

2000 ◽  
Vol 114 (8) ◽  
pp. 576-580 ◽  
Author(s):  
Yoshimichi Ohishi ◽  
Sohtaro Komiyama ◽  
Yoshiki Shiba D.D.S
Keyword(s):  
Cross Sections ◽  
Lingual Nerve ◽  
Confocal Laser ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Predominant Role ◽  
Rhodamine Phalloidin ◽  
Ring Shape ◽  
Pore Cells

The effect on the taste pores of denervation of the chorda tympani nerve in the middle-ear cavity was studied comparing confocal laser microscopy with lingual nerve resection. Taste pore cells were stained for actin with rhodamine-phalloidin and positive fluorescence was observed as a ring shape at the transverse cross sections. Within three days after chorda tympani nerve resection the ring reaction disappeared, although the pore morphology remained intact as seen by scanning electron microscopy. On the other hand, lingual nerve resection did not induce such rapid disappearance of the ring reaction. These results suggest that the chorda tympani nerve plays a predominant role in the maintenance of actin filaments in taste pore cells.

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

2002 ◽  
Vol 719 ◽  
Author(s):  
Myoung-Woon Moon ◽  
Kyang-Ryel Lee ◽  
Jin-Won Chung ◽  
Kyu Hwan Oh
Keyword(s):  
Cross Sections ◽  
Focused Ion Beam ◽  
Imaging System ◽  
Ion Beam ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Glass Substrates ◽  
Atomic Force ◽  
Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

scholarly journals Role of α-Cluster Transfer in the Formation of 20Ne + 16O Cross-Sections at Backward Angles

2021 ◽  
Vol 51 (3) ◽  
pp. 780-787
Author(s):  
Sh. Hamada ◽  
Nourhan M. Elmedalaa ◽  
I. Bondouk ◽  
N. Darwish ◽  
Awad A. Ibraheem
Keyword(s):  
Cross Sections ◽  
Cluster Transfer

scholarly journals Relativistic impulse approximation in the atomic ionization process induced by millicharged particles

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Chen-Kai Qiao ◽  
Shin-Ted Lin ◽  
Hsin-Chang Chi ◽  
Hai-Tao Jia
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Direct Detection ◽  
Impulse Approximation ◽  
Dark Matter Particle ◽  
Ionization Process ◽  
Beyond The Standard Model ◽  
Next Generation ◽  
Many Body ◽  
Atomic Ionization

Abstract The millicharged particle has become an attractive topic to probe physics beyond the Standard Model. In direct detection experiments, the parameter space of millicharged particles can be constrained from the atomic ionization process. In this work, we develop the relativistic impulse approximation (RIA) approach, which can duel with atomic many-body effects effectively, in the atomic ionization process induced by millicharged particles. The formulation of RIA in the atomic ionization induced by millicharged particles is derived, and the numerical calculations are obtained and compared with those from free electron approximation and equivalent photon approximation. Concretely, the atomic ionizations induced by mllicharged dark matter particles and millicharged neutrinos in high-purity germanium (HPGe) and liquid xenon (LXe) detectors are carefully studied in this work. The differential cross sections, reaction event rates in HPGe and LXe detectors, and detecting sensitivities on dark matter particle and neutrino millicharge in next-generation HPGe and LXe based experiments are estimated and calculated to give a comprehensive study. Our results suggested that the next-generation experiments would improve 2-3 orders of magnitude on dark matter particle millicharge δχ than the current best experimental bounds in direct detection experiments. Furthermore, the next-generation experiments would also improve 2-3 times on neutrino millicharge δν than the current experimental bounds.

scholarly journals Few Body Effects in the Electron and Positron Impact Ionization of Atoms

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
R.I. Campeanu ◽  
Colm T. Whelan
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Differential Cross ◽  
Impact Ionization ◽  
Inert Gas ◽  
Interference Effects ◽  
Positron Impact ◽  
Competing Interactions ◽  
Energy Sharing

Triple differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of energy sharing geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions that cannot be separately detected in an experiment with a single projectile. Results will be presented in kinematics where the electron impact ionization appears to be well understood and using the same kinematics positron cross sections will be presented. The kinematics are then varied in order to focus on the role of distortion, post collision interaction (pci), and interference effects.

scholarly journals Assess the Effectiveness of protective Concrete coatings of microbiological sulfuric acid Aggression

2019 ◽  
Vol 97 ◽  
pp. 02022
Author(s):  
Viktor Sopov ◽  
Julia Danchenko ◽  
Ekaterina Latorez
Keyword(s):  
Sulfuric Acid ◽  
Building Structures ◽  
Predominant Role ◽  
Microbiological Processes ◽  
Repair Materials ◽  
Bactericidal Properties ◽  
Mineral Acids ◽  
Concrete Building ◽  
Modified Epoxy

Specification of corrosion processes in sewerage networks, the predominant role of microbiological processes in them requires the protection of concrete with materials resistant to specific biogenic sulfuric acid aggression. The effective protective materials, in this case, are those that, in addition to acid-proofing materials, have bactericidal properties. Polymer composite materials (PCM) of cold curing based on modified epoxy-resin, resins with dispersed oxides as fillers are widely used in construction. Unique properties and simple technologies make it possible to use them as injection formulations for repair, restoration and restoration of building structures and structures, waterproofing and facing materials, for impregnating, gluing and coating metal, wooden, brick and concrete building structures and parts. In the reconstruction and restoration of sewerage collectors operating under conditions of exposure to liquid biochemically aggressive media with mineral acids and organic substances, particular attention is paid to the permeability of repair materials. Based on the results of the study, PCM compositions were chosen whose estimated lifetime is about 20 years, ensuring reliable protection of the sewage collectors from corrosion.

scholarly journals Predominant role of alpha 4-integrins for distinct steps of lymphoma metastasis.

1996 ◽  
Vol 93 (10) ◽  
pp. 4821-4826 ◽  
Author(s):  
U. Gosslar ◽  
P. Jonas ◽  
A. Luz ◽  
A. Lifka ◽  
D. Naor ◽  
...  
Keyword(s):  
Predominant Role
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