scholarly journals Electrical conductivity tensor of dense plasma in magnetic fields

2016 ◽  
Author(s):  
Arus Harutyunyan ◽  
Armen Sedrakian
2014 ◽  
Vol 44 (4) ◽  
pp. 293-312 ◽  
Author(s):  
Tomáš Šoltis ◽  
Ján Šimkanin

Abstract We present an investigation of dynamo in a simultaneous dependence on the non-uniform stratification, electrical conductivity of the inner core and the Prandtl number. Computations are performed using the MAG dynamo code. In all the investigated cases, the generated magnetic fields are dipolar. Our results show that the dynamos, especially magnetic field structures, are independent in our investigated cases on the electrical conductivity of the inner core. This is in agreement with results obtained in previous analyses. The influence of non-uniform stratification is for our parameters weak, which is understandable because most of the shell is unstably stratified, and the stably stratified region is only a thin layer near the CMB. The teleconvection is not observed in our study. However, the influence of the Prandtl number is strong. The generated magnetic fields do not become weak in the polar regions because the magnetic field inside the tangent cylinder is always regenerated due to the weak magnetic diffusion.


Experiments on the magnetic inhibition of thermal convection in horizontal layers of mercury heated from below are described. A large 36½ in. cyclotron magnet reconditioned for hydromagnetic studies was used in these experiments. By using layers of mercury of depth 3 to 6 cm and magnetic fields of strength 500 to 8000 gauss, it has been possible to determine the dependence of the critical Rayleigh number for the onset of instability on the parameter Q 1 ( = σH 2 d 2 / π 2 ρν , where H denotes the strength of the field, σ the electrical conductivity, ν the coefficient of kinematic viscosity, ρ the density and d the depth of the layer) for Q 1 varying between 40 and 1·6 × 10 6 . The experiments fully confirm the theoretical relation derived by Chandrasekhar.


Author(s):  
P. Celliers ◽  
A. Ng ◽  
M.W.C. Dharma-wardana ◽  
F. Perrot

2016 ◽  
Vol 870 ◽  
pp. 95-100
Author(s):  
E.G. Demyanenko ◽  
I.P. Popov

The paper investigates a variety of properties of thin aluminum sheets fabricated using physical action of pulsed magnetic fields and weak pulsed current. The possibility of using thermal resistant aluminum alloys parts in aircraft manufacturing, including ones made by forming processes which require sufficiently high plasticity of initial sheets, is widely discussed. Two possible technological options have been tested for manufacturing sheet samples of Al-Cu-Mn and Al-Mg-Si alloys. A set of properties has been investigated (thermal resistance, mechanical properties, specific electrical conductivity, macrostructure of weldability zones, corrosion resistance of alloy samples. Casted workpieces were thermo-mechanically treated by heating and upsetting to 50 – 55 % with consequent hardening and aging. After that workpieces were subjected to multi-cycle rolling up to 0.3x10-3 m. The achieved results demonstrate that after 400 hours of exposure to 250°C, the thermal resistant parameters by tensile strength are higher after the exposure to weak pulsed currents than after the exposure to pulsed magnetic fields. Maximal thermal resistant parameters by tensile strength and maximal electrical conductivity was achieved in 01327+Sc (Al-Mg-Si) alloy. The mechanical properties, corrosion resistance and Erichsen formability parameters were also determined.


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