Fully kinetic simulations of electron-scale plasma turbulence in the inner heliosphere: a pathfinder for future spacecraft missions

2021 ◽  
Author(s):  
Luca Franci ◽  
Emanuele Papini ◽  
Alfredo Micera ◽  
Daniele Del Sarto ◽  
Giovanni Lapenta ◽  
...  
Keyword(s):  
High Resolution ◽  
Fluid Model ◽  
Plasma Turbulence ◽  
Distribution Functions ◽  
Spectral Break ◽  
Theoretical Predictions ◽  
Large Level ◽  
Two Fluid Model ◽  
Ion Characteristic

<p>We present numerical results from high-resolution fully kinetic simulations of plasma turbulence under the near-Sun conditions encountered by Parker Solar Probe during its first perihelion, characterized by a low plasma beta and a large level of turbulent fluctuations. The recovered spectral properties are in agreement with those from PSP observations and recent high-resolution hybrid simulations just below the ion characteristic scales, i.e., the spectrum of the magnetic field exhibits a steep transition region with a spectral index compatible with -11/3. When the electron scales are reached a spectral break is observed and the spectrum steepens while still showing a clear power law. We discuss theoretical predictions for such a spectral behavior, based on a two-fluid model which assumes that a self-similar energy transfer across scales is occurring, without the need to include any kinetic process. We also analyse the role of magnetic reconnection and the statistics of reconnection events, as well as signatures in the proton and electron distribution functions hinting at mechanisms for energy dissipation. The results of this work represent a step forward in understanding the processes responsible for particle heating and acceleration and therefore on the origin of the solar wind and coronal heating. Furthermore, they allow for reliable predictions for future spacecraft missions investigating electron-scale physics in low-beta plasmas.</p>

scholarly journals Behaviors of B Star Continua and Absorption Features Determined from the TD1 S2/68 “Ultraviolet Bright Star Spectrophotometric Catalogue” and from Copernicus Spectra

1977 ◽  
Vol 4 (2) ◽  
pp. 305-305
Author(s):  
J. M. Vreux ◽  
J. P. Swings
Keyword(s):  
High Resolution ◽  
Spectral Range ◽  
Spectral Type ◽  
B Stars ◽  
Temperature Scales ◽  
Theoretical Predictions ◽  
Q Index ◽  
Absorption Features ◽  
Photometric Index

Ultraviolet low resolution spectra of most of the B stars observed with the S2/68 experiment onboard the TD1 satellite in the spectral range 1350 A - 2500 A are computer-investigated in order to define a grid of standard behaviors (J.M. Vreux and J.P. Swings, 1976 Astron. Astrophys., in press). The behavior of the relative intensities of the Balmer and Paschen continua is studied as a function of the spectral type and the visible photometric index Q: both relations are shown to be luminosity dependent. A comparison to theoretical predictions and to previous studies is also presented. A measure of the slope of the pseudo-continuum drawn between ~ λ 1660 A and ~ λ 2550 A is studied in the same way: the effect of luminosity is discussed in connection with recently proposed temperature scales for super-giants. The behavior of the depths of the absorption features at λλ 1550 A, 1940 A, 2000 A, 2055 A, 2105 A, 2340 A and 2395 A with respect to the spectral type, the Q index and the luminosity class is also briefly presented. Special emphasis is given to the absorption features at λ 1550 A in connection to the discussion of the Felll lines in the ultraviolet spectra of early B stars by J.P. Swings, M. Klutz, J.M. Vreux and E. Peytremann (1976, Astron. Astrophys. Suppl. 25, 193). Preliminary results of a study of high resolution Copernicus spectra in the A 1550 A region are also presented: it is shown that the role of Felll remains predominant for stars of spectral type as early as about BIII - BIIII (J.P. Swings and J.M. Vreux, to be published).

Initiation and Statistical Development of Slug Flow With a High Resolution Two-Fluid Model

2012 ◽  
Author(s):  
R. C. Chucuya ◽  
J. N. E. Carneiro ◽  
A. O. Nieckele
Keyword(s):  
High Resolution ◽  
Slug Flow ◽  
Fluid Model ◽  
Subsequent Development ◽  
Complex Flow ◽  
Mean Values ◽  
Horizontal Pipes ◽  
Dimensional Version ◽  
Two Fluid Model ◽  
Two Fluid

In the present work, the onset and subsequent development of slug flow in horizontal pipes is investigated by accurately solving the transient one-dimensional version of the Two-Fluid Model using a finite volume technique. Growth of disturbances that eventually bridge the pipe section is an automatic outcome of the solution of the discretized equations in a high resolution mesh, avoiding the need for the commonly used phenomenological models for the stratified to slug transition. Slug dynamics evolve naturally without the need of empirical correlations for slug parameters. This methodology (named “slug-capturing”) was proposed before in the literature and the present work represents a rare confirmation of its applicability in predicting this very complex flow regime. Here, different configurations are analyzed and comparisons are performed against different sets of experimental data. Additionally, statistical analysis of the slug parameters is performed and it is shown through comparisons against experimental measurements that this methodology is able not only to provide mean values of e.g. slug and bubble lengths and their evolution inside the pipe, but also shapes of probability density functions (PDFs), with a good degree of accuracy.

On Nature of Electronic States Peculiarities in Strong Correlated Systems. Reasons and Facts

2009 ◽  
Vol 4 (1) ◽  
pp. 56-61
Author(s):  
Leonid Boyarsky ◽  
Aleksandr Blinov
Keyword(s):  
Spin Density ◽  
Crucial Role ◽  
Fluid Model ◽  
Electronic States ◽  
Spin Density Waves ◽  
Correlated Systems ◽  
Two Fluid Model ◽  
Magnetic States ◽  
Two Fluid

Within the framework of offered before two-fluid model of a pseudogap state in Cuprates the hypothesis about a crucial role of inhomogeneities and deviations from stoichiometricity of systems in this state is formulated. The mechanism of occurrence of magnetic states such as spin density waves both above and below of the temperatures of superconductivity transition is offered.

scholarly journals GDB: A global 3D two-fluid model of plasma turbulence and transport in the tokamak edge

2018 ◽  
Vol 232 ◽  
pp. 46-58 ◽  
Author(s):  
Ben Zhu ◽  
Manaure Francisquez ◽  
Barrett N. Rogers
Keyword(s):  
Fluid Model ◽  
Plasma Turbulence ◽  
Tokamak Edge ◽  
Two Fluid Model ◽  
Two Fluid

Hyperbolicity, Discontinuities and Numerics of the Two-Fluid Model

2007 ◽  
Author(s):  
Chih-Hao Chang ◽  
Svetlana Sushchikh ◽  
Loc Nguyen ◽  
Meng-Sing Liou ◽  
Theo Theofanous
Keyword(s):  
Flow Model ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Pressure Coefficient ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Pressure ◽  
Flow Speeds ◽  
Two Fluid Model

The hyperbolicity boundaries of a (droplet) disperse, two-phase flow model at high flow speeds and relative velocities are found, the role of interfacial pressure on regularization is discussed, and the effects on integrability of the system of equations, solver robustness, and convergence properties are determined as a function of position relative to hyperbolic boundaries. We find good agreement between model and physics in that both exhibit a “sensitive” behavior in the transonic region (relative Mach number ∼1, hereafter omitting “relative” for brevity), and in that regularization requires increasing the interfacial pressure coefficient consistently with flow peculiarities in this region. The result is a two-phase flow model that is unconditionally hyperbolic and robust to grid refinement even in the most sensitive numerical tests with no dissipative terms in the equations.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Computer processing of high-resolution images of periodic specimens

1986 ◽  
Vol 44 ◽  
pp. 2-5
Author(s):  
W. Chiu ◽  
M.F. Schmid ◽  
T.-W. Jeng
Keyword(s):  
High Resolution ◽  
Fourier Transforms ◽  
Complex Structure ◽  
Distribution Functions ◽  
Multiple Image ◽  
Cryo Electron Microscopy ◽  
Structure Factors ◽  
Unit Cells ◽  
High Resolution Images ◽  
Phase Probability Distribution

Cryo-electron microscopy has been developed to the point where one can image thin protein crystals to 3.5 Å resolution. In our study of the crotoxin complex crystal, we can confirm this structural resolution from optical diffractograms of the low dose images. To retrieve high resolution phases from images, we have to include as many unit cells as possible in order to detect the weak signals in the Fourier transforms of the image. Hayward and Stroud proposed to superimpose multiple image areas by combining phase probability distribution functions for each reflection. The reliability of their phase determination was evaluated in terms of a crystallographic “figure of merit”. Grant and co-workers used a different procedure to enhance the signals from multiple image areas by vector summation of the complex structure factors in reciprocal space.

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