EFFECTS OF SPACE CHARGE ON THE "EFFECTIVE CROSS SECTION"

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-755-C7-756
Author(s):  
N. S. Kopeika ◽  
T. Karcher ◽  
C.S. Ih.
Keyword(s):  
Space Charge ◽  
Cross Section ◽  
Effective Cross Section

The study of neutron capture processes in AlN nanoparticles

2021 ◽  
pp. 2150127
Author(s):  
T. G. Naghiyev
Keyword(s):  
Computer Modeling ◽  
Cross Section ◽  
Neutron Capture ◽  
Absorption Cross Section ◽  
Effective Cross Section ◽  
Absorption Cross ◽  
Effective Absorption ◽  
Different Types ◽  
N Isotopes

The neutron capture processes in the AlN nanoparticles were investigated by computer modeling. Neutrons absorption were separately investigated for aluminum (Al) and nitrogen (N) atoms in the AlN nanoparticles. The modeling was performed separately for each stable Al and N isotopes, because the effective absorption cross-section of different types of isotopes of Al and N atoms is different. Moreover, effective cross-section spectra of neutron capture for aluminum and nitrogen atoms were comparatively investigated.

scholarly journals Magnetically induced termination of giant planet formation

2018 ◽  
Vol 619 ◽  
pp. A165 ◽  
Author(s):  
A. J. Cridland
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Planet Formation ◽  
Giant Planet ◽  
Effective Cross Section ◽  
Cold Start ◽  
Population Synthesis ◽  
Hot Start ◽  
Gas Accretion ◽  
Planetary Magnetic Field

Here a physical model for terminating giant planet formation is outlined and compared to other methods of late-stage giant planet formation. As has been pointed out before, gas accreting into a gap and onto the planet will encounter the planetary dynamo-generated magnetic field. The planetary magnetic field produces an effective cross section through which gas is accreted. Gas outside this cross section is recycled into the protoplanetary disk, hence only a fraction of mass that is accreted into the gap remains bound to the planet. This cross section inversely scales with the planetary mass, which naturally leads to stalled planetary growth late in the formation process. We show that this method naturally leads to Jupiter-mass planets and does not invoke any artificial truncation of gas accretion, as has been done in some previous population synthesis models. The mass accretion rate depends on the radius of the growing planet after the gap has opened, and we show that so-called hot-start planets tend to become more massive than cold-start planets. When this result is combined with population synthesis models, it might show observable signatures of cold-start versus hot-start planets in the exoplanet population.

The Effect of Boundary Layer Separation on Accuracy of Flow Measurement Using the Gibson Method

2007 ◽  
Author(s):  
F. Z. Sierra ◽  
A. Adamkowski ◽  
G. Urquiza ◽  
J. Kubiak ◽  
H. Lara ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cross Section ◽  
Flow Rate ◽  
Pressure Difference ◽  
Proper Time ◽  
Effective Cross Section ◽  
Boundary Layer Separation ◽  
Water Hammer ◽  
Time Interval ◽  
Geometry Factor

The Gibson method utilizes the effect of water hammer phenomenon (hydraulic transients) in a pipeline for flow rate determination. The method consists in measuring a static pressure difference, which occurs between two cross-sections of the pipeline as a result of a temporal change of momentum from t0 to t1. This condition is induced when the water flow in the pipeline is stopped suddenly using a cut-off device. The flow rate is determined by integrating, within a proper time interval, the measured pressure difference change caused by the water hammer (inertia effect). However, several observations demonstrate that changes of pipeline geometry like diameter change, bifurcations, or direction shift by elbows may produce an effect on the computation of the flow rate. The paper focuses on this effect. Computational simulations have shown that the boundary layer separates when the flow faces sudden changes like these mentioned to above. The separation may reduce the effective cross section area of flow modifying a geometry factor involved into the computation of the flow rate. The remainder is directed to quantify the magnitude of such a factor under the influence of pipeline geometry changes. Results of numerical computations are discussed on the basis of how cross section reductions impact on the geometry factor magnitude and consequently on the mass flow rate.

Effective cross section of the Nd:YAG 1.0641‐μm laser transition

1987 ◽  
Vol 62 (10) ◽  
pp. 4041-4044 ◽  
Author(s):  
K. Fuhrmann ◽  
N. Hodgson ◽  
F. Hollinger ◽  
H. Weber
Keyword(s):  
Cross Section ◽  
Effective Cross Section ◽  
Laser Transition

Computer simulation of (n, p) modifications in silicon nitride (Si3N4) nanoparticles

2020 ◽  
Vol 34 (32) ◽  
pp. 2050318
Author(s):  
T. G. Naghiyev
Keyword(s):  
Computer Simulation ◽  
Silicon Nitride ◽  
Stable Isotope ◽  
Cross Section ◽  
Cross Sections ◽  
Effective Cross Section

(n, p) transmutations in the silicon nitride (Si3N4) nanoparticles by the neutrons at different energies have been studied by computer simulation. The transmutations by neutrons in the nanomaterial were separately investigated for silicon and nitrogen atoms in the Si3N4 particles. Since the effective cross-section of the possible probability of transmutation is different in the various types of silicon and nitrogen atoms, the modeling was performed separately for each stable isotope. The spectra of the effective cross-sections of the (n, p) transmutations for silicon and nitrogen atoms have been studied in relation to each other.

Mathematical Model Analysis of Dispersion and Loss in Photonic Crystal Fibers

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
IS Amiri ◽  
P. Yupapin ◽  
Ahmed Nabih Zaki Rashed
Keyword(s):  
Refractive Index ◽  
Photonic Crystal ◽  
Cross Section ◽  
Photonic Crystal Fibers ◽  
Effective Cross Section ◽  
Confinement Loss ◽  
Cross Section Area ◽  
Section Area ◽  
Crystal Fibers ◽  
Analysis Of Dispersion

AbstractThis study has deeply investigated the basic equations analysis of dispersion and loss in photonic crystal fibers (PCF) within the operating wavelengths of 850, 1,300, and 1,550 nm. The confinement loss, effective refractive index, and effective cross-section area of PCF are also studied. The variations of total dispersion and losses against hole diameter and distance between holes variations in PCF are clarified. Confinement loss, effective refractive index, and effective cross-section area variations for PCF are sketches with the variations of the operating wavelength.

scholarly journals Theoretical Analysis of the Stationary Transport of 1:1 Salt Ions in a Cross-Section of a Desalination Channel, Taking into Account the Non-Catalytic Dissociation/Recombination Reaction of Water Molecules

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 342
Author(s):  
Makhamet Urtenov ◽  
Vitaly Gudza ◽  
Natalia Chubyr ◽  
Inna Shkorkina
Keyword(s):  
Ion Transport ◽  
Space Charge ◽  
Cross Section ◽  
Mutual Influence ◽  
Double Electric Layer ◽  
Limiting Current ◽  
Water Molecules ◽  
Recombination Reaction ◽  
Salt Ions ◽  
The One

In electromembrane systems, the theoretical study of salt ion transport usually uses mathematical models of salt ion transport in the depleted diffusion layer of ion-exchange membranes. This study uses a one-dimensional mathematical model of salt ion transport in a cross-section of a desalination channel formed by anion-exchange and cation-exchange membranes, taking into account an effect of a dissociation/recombination reaction of water molecules. The reaction on the one hand leads to an overlimiting mass transfer due to the effect of exaltation of the limiting current. On the other hand, an appearance of new electric charge carriers (hydrogen and hydroxyl ions) can reduce the space charge that occurs in membranes and suppress an electroconvective mechanism of overlimiting transport. Thus, there is a problem of studying these phenomena together, taking into account their mutual influence, and this article is devoted to the solution of this problem. Theoretically, using a method of mathematical modeling and numerical research, main regularities are established; in particular, it is shown that the dissociation/recombination reaction of water molecules does not lead to the destruction of the double electric layer at the membranes, but also creates a new double electric layer in the middle of the desalination channel. Thus, the space charge and the dissociation/recombination reaction significantly affect each other and simultaneously the transport of salt ions.

Effect of Electrostatic Interactions on Effective Cross-Sections for Collision of Small Particles With Neutral Molecules

1993 ◽  
Vol 46 (1) ◽  
pp. 13 ◽  
Author(s):  
LF Phillips
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Aerosols ◽  
Electrostatic Interactions ◽  
Interstellar Dust ◽  
Effective Cross Section ◽  
Classical Trajectory ◽  
Polar Molecules ◽  
Interstellar Dust Grains ◽  
Geometrical Cross Section

Quasi-classical trajectory calculations have been used to calculate effective collision cross-sections for polar and non-polar molecules with charged and neutral conducting spheres of radius 0.001-0.1 μm over the temperature range 10-400 K. In general the effective cross-section is much larger than the geometrical cross-section, especially for small, highly charged, particles colliding with highly polar molecules at low temperatures. The results may have a bearing on the growth of atmospheric aerosols and of interstellar dust grains.

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