scholarly journals Critical density gradients for small-scale plasma irregularity generation in the E and F regions

2017 ◽  
Vol 122 (9) ◽  
pp. 9588-9602 ◽  
Author(s):  
Roman A. Makarevich
Keyword(s):  
Critical Density ◽  
Small Scale ◽  
Density Gradients ◽  
Plasma Irregularity

Evidence of Small Scale Plasma Irregularity Effects on Whistler Mode Chorus Propagation

2021 ◽  
Vol 48 (5) ◽  
Author(s):  
Poorya Hosseini ◽  
Oleksiy Agapitov ◽  
Vijay Harid ◽  
Mark Gołkowski
Keyword(s):  
Small Scale ◽  
Whistler Mode ◽  
Plasma Irregularity

Anomalous tungsten transport driven by ion temperature gradient turbulence

2021 ◽  
Author(s):  
Shaokang Xu ◽  
Shinya Maeyama ◽  
Tomohiko Watanabe
Keyword(s):  
Particle Transport ◽  
Large Scale ◽  
Critical Density ◽  
Small Scale ◽  
Particle Diffusion ◽  
Tungsten Particle ◽  
Ion Temperature ◽  
Nonlinear Excitation ◽  
Ion Temperature Gradient ◽  
Gyrokinetic Simulations

Abstract The present study reveals that the anomalous tungsten particle transport based on the nonlinear gyrokinetic simulations shares some similarities with that of the linear gyrokinetic study, meanwhile there exist some significant differences. In particular, nonlinear excitation of the linearly stable modes plays a non-negligible role in anomalous tungsten particle transport. The highlighted results are the downshift of the critical density gradient for zero tungsten particle transport and the mod- ification of the poloidal profile of the outward tungsten particle transport, which are both related to the small scale turbulent fluctuations. The former one is due to the outward particle convection produced by the linearly stable modes. The later one is brought by both the linearly stable modes and the large-scale eddies with finite ballooning angle, which flatten the poloidal profile of the particle diffusion and further shift the peak positions of the strongest outward particle transport to the high poloidal angle regions.

scholarly journals Restratification of the Surface Mixed Layer with Submesoscale Lateral Density Gradients: Diagnosing the Importance of the Horizontal Dimension

2008 ◽  
Vol 38 (11) ◽  
pp. 2438-2460 ◽  
Author(s):  
P. J. Hosegood ◽  
M. C. Gregg ◽  
M. H. Alford
Keyword(s):  
Density Gradient ◽  
Mixed Layer ◽  
Large Scale ◽  
Acoustic Doppler Current Profiler ◽  
Small Scale ◽  
Density Gradients ◽  
Surface Mixed Layer ◽  
Vertical Scale ◽  
Current Profiler ◽  
Dimensional Measurements

Abstract A depth-cycling towed conductivity–temperature–depth (CTD) and vessel-mounted acoustic Doppler current profiler (ADCP) were used to obtain four-dimensional measurements of the restratification of the surface mixed layer (SML) at a submesoscale lateral density gradient near the subtropical front. With the objective of studying the role of horizontal processes in restratification, the thermohaline and velocity fields were monitored for 33 h by 16 small-scale (≤15 km2) surveys centered on a drogued float. Daytime warming by insolation caused a unidirectional displacement of the initially vertical isopycnals toward increasing density. Across the entire SML (50-m vertical scale), solar insolation accounted for 60% of observed restratification, but over 10-m scales, the percentage decreased with depth from 80% at 25–35 m to ≤25% at 55–65 m. Below 35 m, stratification was enhanced by the vertically sheared horizontal advection of the lateral density gradient due to a near-inertial wave of ∼100-m vertical wavelength that rotated anticyclonically at the inertial frequency. The phase and similar period (25.4 h) of the local inertial period to the diurnal cycle ensured constructive interference with isopycnal displacements due to insolation. Restratification by sheared advection matched that predicted due to vertically sheared inertial oscillations generated during the geostrophic adjustment of a density front, but direct wind forcing may also have generated the wave that was subsequently modified by interaction with mesoscale vorticity associated with a nearby large-scale front. By further including the effects of lateral uncompensated thermohaline inhomogeneity, the authors can account for 100% ± 20% of the observed N 2 during daytime restratification. No detectable restratification due to the slumping of horizontal density gradients under gravity alone was found.

scholarly journals Flow Field Study of a Top Heated Immiscible Liquid Layer Adjacent to Ice

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Hamed Farmahini Farahani ◽  
Tatsunori Hayashi ◽  
Hirotaka Sakaue ◽  
Ali S. Rangwala
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Immiscible Liquid ◽  
Surface Flow ◽  
Temperature Gradients ◽  
Small Scale ◽  
Density Gradients ◽  
Ice Surface ◽  
Scale Temperature ◽  
Horizontal Temperature Gradients

A series of experiments were conducted to investigate the flow field of a top-heated liquid fuel adjacent to an ice block. The experimental setup consisted of a borosilicate container containing an ice wall and a layer of n-heptane heated from above. Particle Image Velocimetry (PIV) and Background Oriented Schlieren (BOS) measurements were conducted on the liquid -phase. PIV measurements showed a surface flow toward the ice caused by surface -tension forces, which is driven by the horizontal temperature gradients on the liquid surface. A recirculation zone was observed under the free surface and near the ice. The combination of the two flow patterns caused lateral intrusion in the ice, instead of a uniform melting across ice surface. BOS measurements indicated presence of density gradients below the free surface of n-heptane and in regions near the ice block. These density gradients were created by local small-scale temperature gradients. The current experiments were conducted to explore the processes that influence the ice melting by immiscible liquid layers.

scholarly journals Enhancement of electric and magnetic wave fields at density gradients

2006 ◽  
Vol 24 (1) ◽  
pp. 367-379 ◽  
Author(s):  
A. Reiniusson ◽  
G. Stenberg ◽  
P. Norqvist ◽  
A. I. Eriksson ◽  
K. Rönnmark
Keyword(s):  
Small Scale ◽  
Lower Hybrid ◽  
Density Gradients ◽  
Auroral Region ◽  
Wave Fields ◽  
Whistler Mode ◽  
Magnetic Wave ◽  
Hybrid Waves ◽  
Lower Hybrid Waves ◽  
Made In

Abstract. We use Freja satellite data to investigate irregular small-scale density variations. The observations are made in the auroral region at about 1000-1700 km. The density variations are a few percent, and the structures are found to be spatial down to a scale length of a few ion gyroradii. Irregular density variations are often found in an environment of whistler mode/lower hybrid waves and we show that at the density gradients both the electric and magnetic wave fields are enhanced.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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