scholarly journals Thermal Damping of Weak Magnetosonic Turbulence in the Interstellar Medium

2021 ◽  
Vol 922 (1) ◽  
pp. 10
Author(s):  
Kedron Silsbee ◽  
Alexei V. Ivlev ◽  
Munan Gong
Keyword(s):  
Dispersion Relation ◽  
Interstellar Medium ◽  
Neutral System ◽  
Analytic Approximation ◽  
Cutoff Wavelength ◽  
Temperature Dependent ◽  
Compressive Wave ◽  
Heating And Cooling ◽  
Two Fluid ◽  
Turbulent Cascade

Abstract We present a generic mechanism for the thermal damping of compressive waves in the interstellar medium (ISM), occurring due to radiative cooling. We solve for the dispersion relation of magnetosonic waves in a two-fluid (ion-neutral) system in which density- and temperature-dependent heating and cooling mechanisms are present. We use this dispersion relation, in addition to an analytic approximation for the nonlinear turbulent cascade, to model dissipation of weak magnetosonic turbulence. We show that in some ISM conditions, the cutoff wavelength for magnetosonic turbulence becomes tens to hundreds of times larger when the thermal damping is added to the regular ion-neutral damping. We also run numerical simulations, which confirm that this effect has a dramatic impact on cascade of compressive wave modes.

scholarly journals Atomic and Ionized Microstructures in the Diffuse Interstellar Medium

2018 ◽  
Vol 56 (1) ◽  
pp. 489-540 ◽  
Author(s):  
Snežana Stanimirović ◽  
Ellen G. Zweibel
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Spatial Scales ◽  
Physical Processes ◽  
Interstellar Gas ◽  
Local Bubble ◽  
Turbulent Dissipation ◽  
Atomic Structures ◽  
Discrete Structures ◽  
Turbulent Cascade

It has been known for half a century that the interstellar medium (ISM) of our Galaxy is structured on scales as small as a few hundred kilometers, more than 10 orders of magnitude smaller than typical ISM structures and energy input scales. In this review we focus on neutral and ionized structures on spatial scales of a few to ∼104AU, which appear to be highly overpressured, as these have the most important role in the dynamics and energy balance of interstellar gas: the tiny scale atomic structures (TSASs) and extreme scattering events (ESEs) as the most overpressured example of the tiny scale ionized structures (TSISs). We review observational results and highlight key physical processes at AU scales. We present evidence for and against microstructures as part of a universal turbulent cascade and as discrete structures, and we review their association with supernova remnants, the Local Bubble, and bright stars. We suggest a number of observational and theoretical programs that could clarify the nature of AU structures. TSAS and TSIS probe spatial scales in the range of what is expected for turbulent dissipation scales and are therefore of key importance for constraining exotic and not-well-understood physical processes that have implications for many areas of astrophysics. The emerging picture is one in which a magnetized, turbulent cascade, driven hard by a local energy source and acting jointly with phenomena such as thermal instability, is the source of these microstructures.

A Transient Elastic-Plastic Thermal Stress Analysis of Flame Forming

1973 ◽  
Vol 95 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Y. Iwamura ◽  
E. F. Rybicki
Keyword(s):  
Thermal Stress ◽  
Stress Analysis ◽  
Material Properties ◽  
Transient Behavior ◽  
Heated Plate ◽  
Plastic Range ◽  
Temperature Dependent ◽  
Elastic Plastic ◽  
Heating And Cooling ◽  
Flame Forming

The work described here is part of a larger experimental and theoretical program directed at obtaining a better understanding of the mechanics of flame bending. A capability for predicting the transient behavior of a line heated plate during heating and cooling is presented. Material properties are temperature dependent. Elastic-plastic stress-strain relations are used. Material unloading from the plastic range is treated. Deformations of a plate are predicted at various times during heating and cooling and compared with experimental results. The analysis is also carried out for consecutive heating and cooling cycles.

TEMPERATURE DEPENDENCE OF JOSEPHSON PLASMA MODES IN Bi2Sr2CaCu2O8+δ NEAR Tc

2000 ◽  
Vol 14 (05) ◽  
pp. 547-554
Author(s):  
KAZUO KADOWAKI ◽  
ITSUHIRO KAKEYA ◽  
TETSU WAKABAYASHI ◽  
RYO NAKAMURA ◽  
SABURO TAKAHASHI
Keyword(s):  
Plasma Frequency ◽  
Fluid Model ◽  
Microwave Frequency ◽  
Tunneling Probability ◽  
Temperature Dependent ◽  
Plasma Energy ◽  
Longitudinal Plasma ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Josephson Plasma

A strong temperature dependent phenomenon of the Josephson plasma resonance mode has been found in high-Tc superconductor Bi 2 Sr 2 CaCu 2 O 8+δ in a microwave frequency region between 9 and 50 GHz. The longitudinal plasma frequency sharply decreases and disappears just below Tc. The extrapolated plasma energy is estimated to be ℏω p (0)=2.59× 10-4 eV . Since the plasma frequency, ω p , is determined by the Anderson-Higgs–Kibble mechanism and it is expected to be temperature independent, this phenomenon can not be accounted for by the conventional underst and ing of the plasma mode in superconductors. Experimental results are discussed in terms of the two fluid model, in which the intrinsic Josephson nature of the coupling restricting the tunneling probability of quasiparticles between layers is considered to be as a dumping mechanism of the quasiparticles in this system.

Temperature Dependence of a Kohn Anomaly in Molybdenum

1972 ◽  
Vol 50 (23) ◽  
pp. 3069-3070 ◽  
Author(s):  
W. J. L. Buyers ◽  
B. M. Powell ◽  
A. D. B. Woods
Keyword(s):  
Dispersion Relation ◽  
Temperature Dependence ◽  
Phonon Dispersion ◽  
Temperature Dependent ◽  
Phonon Dispersion Relation

Measurements of the [00ζ]L or Δ1 branch of the phonon dispersion relation for molybdenum at 88 and 298 K over the range [Formula: see text] show that the shape of the Kohn anomaly in this region is not strongly temperature dependent.

scholarly journals Determination of allowable fluid temperature during start-up operation of outlet header under the assumption of constant and temperature-dependent material properties

2013 ◽  
Vol 34 (3) ◽  
pp. 3-14
Author(s):  
Dariusz Rząsa ◽  
Piotr Duda
Keyword(s):  
Power Plants ◽  
Operation Time ◽  
Optimum Operating ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Temperature Dependent ◽  
Allowable Limit ◽  
Heating And Cooling ◽  
Start Up ◽  
Operation Cycle

Abstract Modern supercritical power plants operate at very high temperatures and pressures. Thus the construction elements are subjected to both high thermal and mechanical loads. As a result high stresses in those components are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stresses that are defined according to boiler regulations. It is important to find optimum operating parameters, that can assure safe heating and cooling processes. The optimum parameters define temperature and pressure histories that can keep the highest stresses within allowable limit and reduce operation time as much as possible. In this paper a new numerical method for determining optimum working fluid parameters is presented. In this method, properties of steel can be assumed as constant or temperature dependent. The constant value is taken usually at the average temperature of the operation cycle. For both cases optimal parameters are determined. Based on these parameters start-up operations for both cases are conducted. During entire processes stresses in the heated element are monitored. The results obtained are compared with German boiler regulations - Technische Regeln fur Dampfkessel 301.

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