Kapitza resistance of cerium ethylsulphate

1968 ◽  
Vol 46 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Hans Glättli
Keyword(s):  
Magnetic Field ◽  
Liquid Helium ◽  
Spin System ◽  
Energy Transport ◽  
Relaxation Times ◽  
Bath Temperature ◽  
Limiting Factor ◽  
Kapitza Resistance ◽  
Experimental Values ◽  
Λ Point

Spin–bath relaxation times τ of cerium ethylsulphate (CeES) immersed in liquid helium have been measured at magnetic fields up to 6 kOe. The electronic spin system of CeES has been heated by pulsed microwave radiation and the return to the equilibrium bath temperature has been monitored, using the optical Faraday rotation. At temperatures below the λ point of liquid helium, τ is a few ms and weakly dependent on magnetic field and temperature. It is assumed that the Kapitza boundary resistance Rk is the limiting factor in the energy transport between the spin system of CeES and the surrounding liquid helium. This assumption is supported by measurements of τ above the λ point between CeES and liquid or gaseous helium. Rk has been calculated from the experimental values of τ using a simple thermodynamical model. The resulting temperature dependence can be fitted with the expression Rk = 30 T−2.4 cm2 °K s (joule)−1 independent of magnetic field. The same model has been applied to PrES, which has been shown previously to exhibit a similar relaxation behavior. The results of Rk are close to those obtained for CeES.

scholarly journals Magnetic-field induced quantum phase transition and critical behavior in a gapped spin system

2007 ◽  
Vol 310 (2) ◽  
pp. 1352-1354 ◽  
Author(s):  
F. Yamada ◽  
T. Ono ◽  
M. Fujisawa ◽  
H. Tanaka ◽  
T. Sakakibara
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Quantum Phase Transition ◽  
Spin System ◽  
Critical Behavior ◽  
Quantum Phase

scholarly journals Rotation and Magnetic Field Effect on Surface Waves Propagation in an Elastic Layer Lying over a Generalized Thermoelastic Diffusive Half-Space with Imperfect Boundary

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
S. M. Abo-Dahab ◽  
Kh. Lotfy ◽  
A. Gohaly
Keyword(s):  
Magnetic Field ◽  
Surface Waves ◽  
Half Space ◽  
Attenuation Coefficient ◽  
Elastic Layer ◽  
Finite Thickness ◽  
Relaxation Times ◽  
Magnetic Field Effect ◽  
Plane Boundary ◽  
Special Cases

The aim of the present investigation is to study the effects of magnetic field, relaxation times, and rotation on the propagation of surface waves with imperfect boundary. The propagation between an isotropic elastic layer of finite thickness and a homogenous isotropic thermodiffusive elastic half-space with rotation in the context of Green-Lindsay (GL) model is studied. The secular equation for surface waves in compact form is derived after developing the mathematical model. The phase velocity and attenuation coefficient are obtained for stiffness, and then deduced for normal stiffness, tangential stiffness and welded contact. The amplitudes of displacements, temperature, and concentration are computed analytically at the free plane boundary. Some special cases are illustrated and compared with previous results obtained by other authors. The effects of rotation, magnetic field, and relaxation times on the speed, attenuation coefficient, and the amplitudes of displacements, temperature, and concentration are displayed graphically.

scholarly journals MRI under hyperbaric air and oxygen: Effects on local magnetic field and relaxation times

2013 ◽  
Vol 72 (4) ◽  
pp. 1176-1181 ◽  
Author(s):  
Eric R. Muir ◽  
Damon Cardenas ◽  
Shiliang Huang ◽  
John Roby ◽  
Guang Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Relaxation Times ◽  
Local Magnetic Field ◽  
Oxygen Effects

Optical detection of magnetic field with Mn4+:K2SiF6 phosphor from room to liquid helium temperatures

2017 ◽  
Vol 110 (21) ◽  
pp. 212405 ◽  
Author(s):  
Zhiqiang Zhong ◽  
Xia Wang ◽  
Junpei Zhang ◽  
Haizheng Zhong ◽  
Jun-Bo Han
Keyword(s):  
Magnetic Field ◽  
Liquid Helium ◽  
Optical Detection

scholarly journals Self-Consistent Models for Small Photospheric Flux Tubes

1983 ◽  
Vol 102 ◽  
pp. 67-71
Author(s):  
W. Deinzer ◽  
G. Hensler ◽  
D. Schmitt ◽  
M. Schüssler ◽  
E. Weisshaar
Keyword(s):  
Magnetic Field ◽  
Flux Tube ◽  
Energy Transport ◽  
Numerical Study ◽  
Momentum Equation ◽  
Mhd Equations ◽  
Compressible Medium ◽  
Solar Photosphere ◽  
Slab Geometry ◽  
Element Technique

We give a short summary of some results of a numerical study of magnetic field concentrations in the solar photosphere and upper convection zone. We have developed a 2D time dependent code for the full MHD equations (momentum equation, equation of continuity, induction equation for infinite conductivity and energy equation) in slab geometry for a compressible medium. A Finite-Element-technique is used. Convective energy transport is described by the mixing-length formalism while the diffusion approximation is employed for radiation. We parametrize the inhibition of convective heat flow by the magnetic field and calculate the material functions (opacity, adiabatic temperature gradient, specific heat) self-consistently. Here we present a nearly static flux tube model with a magnetic flux of ∼ 1018 mx, a depth of 1000 km and a photospheric diameter of ∼ 300 km as the result of a dynamical calculation. The influx of heat within the flux tube at the bottom of the layer is reduced to 0.2 of the normal value. The mass distribution is a linear function of the flux function A: dm(A)/dA = const. Fig. 1 shows the model: Isodensities (a), fieldlines (b), isotherms (c) and lines of constant continuum optical depth (d) are given. The “Wilson depression” (height difference between τ = 1 within and outside the tube) is ∼ 150 km and the maximum horizontal temperature deficit is ∼ 3000 K. Field strengths as function of x for three different depths and as function of depth along the symmetry axis are shown in (e) and (f), respectively. Note the sharp edge of the tube.

scholarly journals Excitation of kinetic Alfvén turbulence by MHD waves and energization of space plasmas

2004 ◽  
Vol 11 (5/6) ◽  
pp. 535-543 ◽  
Author(s):  
Y. Voitenko ◽  
M. Goossens
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Energy Transport ◽  
Plasma Heating ◽  
Alfven Wave ◽  
Mhd Waves ◽  
Space Plasmas ◽  
Small Scale ◽  
The Magnetic Field ◽  
Dissipation Range

Abstract. There is abundant observational evidence that the energization of plasma particles in space is correlated with an enhanced activity of large-scale MHD waves. Since these waves cannot interact with particles, we need to find ways for these MHD waves to transport energy in the dissipation range formed by small-scale or high-frequency waves, which are able to interact with particles. In this paper we consider the dissipation range formed by the kinetic Alfvén waves (KAWs) which are very short- wavelengths across the magnetic field irrespectively of their frequency. We study a nonlocal nonlinear mechanism for the excitation of KAWs by MHD waves via resonant decay AW(FW)→KAW1+KAW2, where the MHD wave can be either an Alfvén wave (AW), or a fast magneto-acoustic wave (FW). The resonant decay thus provides a non-local energy transport from large scales directly in the dissipation range. The decay is efficient at low amplitudes of the magnetic field in the MHD waves, B/B0~10-2. In turn, KAWs are very efficient in the energy exchange with plasma particles, providing plasma heating and acceleration in a variety of space plasmas. An anisotropic energy deposition in the field-aligned degree of freedom for the electrons, and in the cross-field degrees of freedom for the ions, is typical for KAWs. A few relevant examples are discussed concerning nonlinear excitation of KAWs by the MHD wave flux and consequent plasma energization in the solar corona and terrestrial magnetosphere.

The onset of oscillatory instability in a rotating layer of mercury heated from below and subject to a magnetic field

1986 ◽  
Vol 407 (1833) ◽  
pp. 313-324 ◽  
Keyword(s):  
Magnetic Field ◽  
Rayleigh Number ◽  
Oscillatory Instability ◽  
Experimental Values ◽  
Oscillatory Instabilities

A comparison is made between the predicted theoretical values of the Rayleigh number at the onset of instability in both the stationary and oscillatory modes with the observed experimental values of Nakagawa’s ( Proc. R. Soc. Lond . A 242, 81‒88 (1957)), when a layer of mercury is heated from below and simultaneously subjected to the effects of a magnetic field and rotation. The theoretical cell sizes and the gyration frequencies for the onset of oscillatory instabilities are also presented.

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