scholarly journals Considerations of A Two-Fluid Heliospheric Plasma Dynamics Under Dominant Electron Pressure

2021 ◽  
Vol 4 (4) ◽  
Keyword(s):  
Energy Flow ◽  
Plasma Pressure ◽  
Space Plasmas ◽  
Plasma Dynamics ◽  
Electron Pressure ◽  
Plasma Energy ◽  
Energy Flows ◽  
Solar Wind Termination Shock ◽  
Plasma Theory ◽  
Two Fluid

Electrons in plasma physics mostly are the underestimated species, since usually they only have to guarantee electric quasineutrality, but don’t count in terms of mass-, momentum-, and energy flows. This is different in space plasmas like the heliospheric plasma, especially the plasma downstream of the solar wind termination shock. Here it has become evident more recently that electrons dominate the plasma pressure and, connected with that, the plasma energy flow. Under these conditions a two-fluid plasma theory is needed to adequately describe fields and flows. We first here develop a pure two-fluid thermodynamics of such two-fluid plasmas and then study the actual situation in case of the heliospheric plasma that the electron pressure is dominating over the proton pressure. Under such auspices the electron pressure determines the mass- and momentum flows of the plasma and in fact decreases with the decrease of bulk velocity of the flow

Statistical energy analysis as a tool for quantifying sound and vibration transmission paths

1994 ◽  
Vol 346 (1681) ◽  
pp. 449-464 ◽  
Keyword(s):  
Energy Flow ◽  
Complex Structure ◽  
Linear Equations ◽  
Least Square ◽  
Net Energy ◽  
Sea Temperature ◽  
Energy Flows ◽  
The Difference ◽  
Symmetry Relations ◽  
Loss Factors

When a complex structure is excited in several different ways by different sources, the sea energy balance equations result in a set of linear equations that can be used to calculate loss factors, coupling loss factors or net energy flows and incoming powers. If certain symmetry relations are used, and/or if some prior knowledge about the system is available, the set of linear equations is overdetermined and can be solved by a least square technique. A good indicator for the direction of the energy flow is the SEA temperature of the subsystems. Experiments and computer simulations performed on three plate arrangements gave in general good results when the coupling was weak and there were more than three modes in the frequency band of interest. Not so good results were obtained when a small energy flow has to be measured as the difference of large quantities.

scholarly journals Plasma Flow Generation due to the Nonlinear Alfvén Wave Propagation around a 3D Magnetic Null Point

2021 ◽  
Vol 922 (2) ◽  
pp. 123
Author(s):  
S. Sabri ◽  
H. Ebadi ◽  
S. Poedts
Keyword(s):  
Plasma Flow ◽  
Current Density ◽  
Flow Behavior ◽  
Plasma Pressure ◽  
Null Point ◽  
Oscillatory Behavior ◽  
Alfven Wave ◽  
Plasma Energy ◽  
Magnetic Null ◽  
Magnetic Null Point

Abstract The behavior of current density accumulation around the sharp gradient of magnetic field structure or a 3D magnetic null point and with the presence of finite plasma pressure is investigated. It has to be stated that in this setup, the fan plane locates at the xy plane and the spine axis aligns along the z-axis. Current density generation in presence of the plasma pressure that acts as a barrier for developing current density is less well understood. The shock-capturing Godunov-type PLUTO code is used to solve the magnetohydrodynamic set of equations in the context of wave-plasma energy transfer. It is shown that propagation of Alfvén waves in the vicinity of a 3D magnetic null point leads to current density excitations along the spine axis and also around the magnetic null point. Besides, it is pointed out the x component of current density has oscillatory behavior while the y and z components do not show this property. It is plausible that it happens because the fan plane encompasses separating unique topological regions, while the spine axis does not have this characteristic and is just a line without separate topological regions. Besides, current density generation results in plasma flow. It is found that the y component of the current density defines the x component of the plasma flow behavior, and the x component of the current density prescribes the behavior of the y component of the plasma flow.

Diffusion equation modelling for energy flow analysis in reverberation chambers

2021 ◽  
Vol 263 (1) ◽  
pp. 5637-5642
Author(s):  
Ryan Hao ◽  
Ning Xiang
Keyword(s):  
Diffusion Equation ◽  
Energy Flow ◽  
Flow Analysis ◽  
Equation Model ◽  
Computationally Efficient ◽  
Reverberation Chamber ◽  
Sound Fields ◽  
Energy Flows ◽  
Standardized Measurement ◽  
Reverberation Chambers

Noise is a growing concern in the built environment. Sound absorbers are a viable option for noise treatment. However, the characterization of their absorption coefficient in standardized measurement chambers still show challenges for high accuracy as required in practice. In recent years, experimental analysis has shown that assumptions of diffuse sound fields made in well-known reverberation chambers are unfulfilled. Specifically, that sound intensities in chamber-based measurement methods are presumed to be isotropic or diffuse. Diffusion equation models have shown dramatic changes in energy flow in the presence of highly absorptive materials under test. This has been attributed to well-documented inconsistencies reported from reverberation chamber measurements across different laboratories. This work will demonstrate that the diffusion equation model is proving to be a computationally efficient and viable method for predicting sound energy flows, garnering an increasing amount of interest from the acoustical community.

Energy Balance of Indian Villages: A Case Study of Seven Villages

2018 ◽  
Vol 1 (1) ◽  
pp. 77-103
Author(s):  
Amit Garg ◽  
Jaypalsinh Chauhan ◽  
Abha Chhabra ◽  
Tirthankar Nag
Keyword(s):  
Energy Balance ◽  
Energy Flow ◽  
Flow Model ◽  
Crop Yields ◽  
Gujarat State ◽  
Forest Density ◽  
Residential Sector ◽  
Energy Flows ◽  
Stock Change

This paper estimates the rural energy balance of 7 Indian villages of different agro-climate zones. This was done through primary survey of households in each village covering energy consumption, production, export, import and stock change across Crop, Livestock, Industry/Trade, Tree outside forest/plantations and Residential Sector. An energy flow model was created to capture all the various energy flows at household levels. Two villages are showing Negative annual energy balance—one is the desert village of Gujarat state and another is a tribal village of Mizoram state. All other villages were found to be energy positive mainly due to high forest density and high crop yields.

scholarly journals Investigation into the Effect of Increasing Target Temperature and the Size of Cavity Confinements on Laser-Induced Plasmas

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 393
Author(s):  
Hongbing Yao ◽  
Emmanuel Asamoah ◽  
Pengyu Wei ◽  
Jiawei Cong ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Sample Surface ◽  
Plasma Pressure ◽  
Sample Temperature ◽  
Collision Probability ◽  
Radiation Process ◽  
Plasma Dynamics ◽  
Fundamental Wavelength ◽  
Air Density ◽  
General Improvement

In this work, the effect of the sample temperature on the magnesium (Mg) and titanium (Ti) plasmas generated by a Q-switched Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser operating at its fundamental wavelength of 1064 nm has been investigated. We observed that increasing the sample temperature significantly enhanced the emission intensities of the plasmas. Comparing the emission peak intensities of the case of 100 °C to the case of 300 °C, we recorded a substantial enhancement of the peak intensities of the latter compared to the former. From these results it can be observed that increasing the sample temperature has a significant effect on the emission intensities of the plasmas. We also studied the plasma dynamics and found that increasing the sample temperature also decreases the air density around the Mg sample surface. The reduction in the air density resulted in a decrease in the radiation process and lowers collision probability. Furthermore, as the plasma expands, the plasma pressure also decreases. In addition, we also employed circular and square cavities to confine the titanium plasma, and investigated the effect of the sizes of the circular and square cavities on the titanium plasma. We observed a general improvement in the emission intensities with both the circular and square cavities and attributed this improvement to the plasma compression effect of the shock waves produced by the plasma within the cavities.

Efficiency of Energy Transfer in a Small Plasma Focus Device

2005 ◽  
Vol 107 ◽  
pp. 95-98
Author(s):  
Dusit Ngamrungroj ◽  
Rattachat Mongkolnavin ◽  
Chiow San Wong
Keyword(s):  
Energy Transfer ◽  
Plasma Focus ◽  
Pressure Range ◽  
Initial Energy ◽  
Energy Transfer Efficiency ◽  
Plasma Focus Device ◽  
Transfer Efficiency ◽  
Plasma Dynamics ◽  
Plasma Energy ◽  
Basic Model

A study of energy transfer in a small plasma focus device has been carried out during its axial phase. The snow-plough model has been used in the simulation as a basic model for the calculation of plasma dynamics. The energy transferred to the plasma is calculated by considering the work done by the electromagnetic piston during the axial phase. It was found that the plasma energy calculated by this model agrees well with the experimental data within the pressure range of 1 mbar to 4 mbar if the mass shedding effect is included in the model. According to the present computation, the energy transferred into the plasma, in the case of a plasma focus with 2.3 kJ initial energy operated with nitrogen gas within the pressure range of 1 to 4 mbar, is between 224 J to 250 J. This corresponds to energy transfer efficiency of 9.6% to 10.7%. The mass shedding factor decreases from 0.23 to 0.069 with increasing pressure. Correspondingly, the energy transfer efficiency changes slightly at a higher pressure.

Long-term Experiments on the Stability of Two Fish Populations in Previously Unexploited Arctic Lakes

1994 ◽  
Vol 51 (1) ◽  
pp. 209-225 ◽  
Author(s):  
Lionel Johnson
Keyword(s):  
Energy Flow ◽  
Environmental Variability ◽  
Salvelinus Alpinus ◽  
Stable State ◽  
Arctic Char ◽  
Arctic Lakes ◽  
System Stability ◽  
Fish Populations ◽  
Ecosystem Structure ◽  
Energy Flows

Previous research indicated that fish populations in arctic lakes maintain a constant size distribution and abundance in the face of the environmental variability experienced over their recent history. Such stability was tested over 15 seasons in Little Nauyuk and Gavia lakes (Northwest Territories) which contained previously undisturbed populations of Arctic char (Salvelinus alpinus). Initially, the length–frequency distribution of Arctic char in Little Nauyuk Lake was bell shaped, and in Gavia Lake, it could be described by a negative logarithmic expression. Initial sampling of Gavia Lake removed the largest fish, allowing a well-defined mode to develop (cf. Little Nauyuk Lake). In both lakes the modal value remained constant throughout the exploitation phase. When fishing ceased the populations returned to their original state without evident oscillation. The stable state of the dominant population is considered to be one of "least dissipation". It is hypothesized that ecosystem structure depends on countervailing forces, one tending to decelerate energy flow through the ecosystem and the second tending to accelerate it. For ecosystems to exist, the tendency to decelerate energy flow must dominate system behaviour over ecological time. An ecosystem is regarded as a hemeorhetic system, stability seeking through the stabilization of energy flows.

scholarly journals Deducing Earth’s Global Energy Flows from a Simple Greenhouse Model

2018 ◽  
Author(s):  
Miklos Zagoni
Keyword(s):  
Energy Flow ◽  
Climate Models ◽  
Water Cycle ◽  
Flow System ◽  
Single Layer ◽  
Longwave Radiation ◽  
Data Sets ◽  
Global Energy ◽  
Energy Flows ◽  
Global Mean

Earth atmosphere is almost opaque in the infrared: about 374 W/m2 is absorbed by the atmosphere out of 396 W/m2 surface upward longwave radiation, and only about 22 W/m2 leaves the system unabsorbed in the atmospheric window. This makes rise to the idea to approximate the annual global mean energy flow system from a simple idealized greenhouse model, where the surface is surrounded by a single-layer shortwave (SW) transparent, longwave (LW) opaque, non-turbulent atmosphere. The energy flows in this geometry can be described by elementary arithmetic relationships. Starting from this model, the realistic Earth’s atmosphere can be achieved by introducing partial atmospheric SW opacity, partial atmospheric LW transparency and turbulent fluxes during the course of the deduction. The resulted global mean energy flow system is then compared to several data sets such as satellite observations from the CERES mission; estimates using direct surface observations and climate models; global energy and water cycle assessments; and independent detailed clear-sky radiative transfer computations. We find that the deduction from this idealized model approximates the real values in Earth energy budget with reasonable accuracy: the deduced fluxes and the observed ones are consistent within the acknowledged error of observations; while fundamental features of the initial geometry like special ratios and definite relationships between the fluxes are preserved.

scholarly journals Minimal Focal Spot Size Measured Based on Intensity and Power Flow

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5505
Author(s):  
Victor V. Kotlyar ◽  
Sergey S. Stafeev ◽  
Vladislav D. Zaitsev
Keyword(s):  
Linear Polarization ◽  
Energy Flow ◽  
Power Flow ◽  
Focal Spot ◽  
Spot Size ◽  
Optical Vortices ◽  
Focal Spot Size ◽  
Minimum Diameter ◽  
Circular Symmetry ◽  
Energy Flows

It is shown, theoretically and numerically, that the distributions of the longitudinal energy flow for tightly focused light with circular and linear polarization are the same, and that the spot has circular symmetry. It is also shown that the longitudinal energy flows are equal for optical vortices with unit topological charge and with radial or azimuthal polarization. The focal spot has a minimum diameter (all other characteristics being equal), which is measured based on the intensity of an optical vortex with azimuthal polarization. The diameter of the focal spot calculated from the energy flow for light with circular or linear polarization is slightly larger (by a fraction of a percentage). The magnitude of the diameter based on the intensity plays a role in the interaction of light with matter, and the magnitude of the diameter based on the energy flux affects the resolution in optical microscopy which is crucial in sensorial applications.

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