scholarly journals An Investigation of r.f. Travelling Wave Current Drive Using the Model

1988 ◽  
Vol 41 (4) ◽  
pp. 587 ◽  
Author(s):  
WK Bertram
Keyword(s):  
Magnetic Field ◽  
Quantitative Agreement ◽  
Travelling Wave ◽  
Current Drive ◽  
Experimental Investigations ◽  
Initial Increase ◽  
Toroidal Plasma ◽  
Subsequent Decrease ◽  
Observed Behaviour ◽  
Drive Model

Previous experimental investigations into the use of travelling r.f. waves to drive steady toroidal currents in a toroidal plasma have shown that It, the amount of current driven, is strongly dependent on the ratio of the static toroidal magnetic field Bz, to the strength of the r.f. magnetic field BO). This dependence is characterised by an initial increase and subsequent decrease of It when Btl BfIJ increases. It is shown that this observed behaviour is entirely consistent with the behaviour predicted by the <i X B) current drive model. Results from .numerical computations using the <i X B) model show good quantitative agreement with the published experimental results.

scholarly journals Experimental and theoretical progress in pipe flow transition

2008 ◽  
Vol 366 (1876) ◽  
pp. 2671-2684 ◽  
Author(s):  
A.P Willis ◽  
J Peixinho ◽  
R.R Kerswell ◽  
T Mullin
Keyword(s):  
Pipe Flow ◽  
Quantitative Agreement ◽  
Travelling Wave ◽  
Turbulent Pipe Flow ◽  
Transition To Turbulence ◽  
Reynolds Number Flow ◽  
Threshold Amplitude ◽  
Number Flow ◽  
The Stability ◽  
Laminar State

There have been many investigations of the stability of Hagen–Poiseuille flow in the 125 years since Osborne Reynolds' famous experiments on the transition to turbulence in a pipe, and yet the pipe problem remains the focus of attention of much research. Here, we discuss recent results from experimental and numerical investigations obtained in this new century. Progress has been made on three fundamental issues: the threshold amplitude of disturbances required to trigger a transition to turbulence from the laminar state; the threshold Reynolds number flow below which a disturbance decays from turbulence to the laminar state, with quantitative agreement between experimental and numerical results; and understanding the relevance of recently discovered families of unstable travelling wave solutions to transitional and turbulent pipe flow.

Experimental investigations on finishing of a brass specimen by magneto-rheological honing technique

2021 ◽  
pp. 251659842110157
Author(s):  
Chinu Kumari ◽  
Sanjay Kumar Chak
Keyword(s):  
Magnetic Field ◽  
Process Parameters ◽  
Surface Finish ◽  
Rotational Speed ◽  
Field Application ◽  
Surface Finishing ◽  
Experimental Investigations ◽  
Significant Parameter ◽  
Magnetizing Current ◽  
Magneto Rheological

Magneto-rheological abrasive honing (MRAH) is an unconventional surface finishing technique that relies on abrasives mixed with a unique finishing fluid, which changes its characteristics on magnetic field application. This process imparts nanometric-level surface finish with a significant amount of uniformity. Rotating motion of the workpiece and continuous reciprocation of the finishing fluid in the MRAH process are recognized as the major aspects for adopting this process in finishing non-magnetic materials. The finishing obtained through the MRAH process relies on the workpiece’s material properties and process parameters such as concentration of abrasives in finishing fluid, rotational speed of the workpiece, and magnetic field strength/magnetizing current. To study the efficacy of MRAH process, a parametric study was conducted by performing few experiments on a brass workpiece. Design of experiment approach was adopted to plan the experiments, and the effect of different values of magnetizing current, the concentration of abrasives, and rotational speed on the surface finish were analyzed through the application of analysis of variance (ANOVA). From ANOVA, the rotational speed was found as the most significant parameter with a contribution of 48.90% on % reduction in roughness value (%∇Ra). Around 57% of roughness reduction was obtained at the optimized value of process parameters.

Corrosion Phenomena of Eurofeer Steel in Pb-17Li Stationary Flow at Magnetic Field

2006 ◽  
Author(s):  
E. Platacis ◽  
I. Bucenieks ◽  
F. Muktupavel ◽  
A. Shishko
Keyword(s):  
Magnetic Field ◽  
Structural Material ◽  
Corrosion Rate ◽  
Liquid Metals ◽  
Metal Flow ◽  
Stationary Flow ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Martensitic Steels ◽  
Eurofer 97

Search of new energy sources draws the increasing attention to use for this purpose of reactors. In the Europe some years the program EUROATOM uniting scientific of the many countries for the decision of constructive problems at designing of fusion reactors operates. One of the main things in this program is the problem of liquid metals breeder blanket behaviour. Structural material of blanket should meet high requirements because of extreme operating conditions. Therefore the knowledge of the effect of metals flow velocity, temperatures and also a neutron irradiation and a magnetic field on the corrosion processes are necessary. At the moment the eutectic lead -lithium (Pb-17Li) is considered as the most suitable tritium breeder material [1–3]. In turn as a structural material have been tested both many austenitic and ferritic-martensitic steels [2–4]. As the optimum variant is considered steel EUROFER 97, which corrosion rate in liquid Pb-17Li eutectic is the least [3,4]. However, these results have been received without taking into account influence of a strong magnetic field. At the same time, this influence should be essential, as because of change of hydrodynamics of a liquid metal flow, and because of interaction of a magnetic field with a ferromagnetic steel. It has been shown in [5,6] that the magnetic field leads to increase of corrosion rate for austenitic (316L) and martensitic (1,4914) steels. Experimental data for EUROFER 97, and also a theoretical substantiation of the phenomenon are absent, that creates essential difficulties for forecasting working capacity of blanket construction. The aim of presented work were the theoretical and experimental investigations of magnetic field influence on the corrosion of EUROFER 97 steel exposed to flowing Pb-17 Li in specific designed loop.

Oscillating magnetic field current drive in a spherical plasma device

2000 ◽  
Vol 42 (7) ◽  
pp. 807-821 ◽  
Author(s):  
S Xu ◽  
W Luo ◽  
K N Ostrikov ◽  
J Ahn ◽  
S Lee
Keyword(s):  
Magnetic Field ◽  
Current Drive ◽  
Plasma Device ◽  
Oscillating Magnetic Field ◽  
Spherical Plasma

scholarly journals Исследования альфвеновских мод на токамаке Глобус-М2 с использованием многочастотного допплеровского рефлектометра V-диапазона

2021 ◽  
Vol 47 (4) ◽  
pp. 41
Author(s):  
В.В. Буланин ◽  
И.М. Балаченков ◽  
В.И. Варфоломеев ◽  
В.К. Гусев ◽  
Г.С. Курскиев ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Doppler Frequency ◽  
Spherical Tokamak ◽  
Frequency Shifts ◽  
Toroidal Plasma ◽  
V Band ◽  
New Information ◽  
Spectral Components ◽  
Central Regions ◽  
Doppler Frequency Shifts

New information on the development of Alfvén modes in the Globus-M2 spherical tokamak is presented. The data were obtained using a V-band Doppler reflectometer with probing radiation frequencies from 50 to 75 GHz. A microwave harmonic synthesizer was used as a multifrequency probing source. As a result of using a new reflectometer, the localization of the toroidal Alfvén eigenmode has been determined at a magnetic field of 0.5 T. The spectral components of the Alfvén mode with Doppler frequency shifts due to toroidal plasma rotation have been recorded. The so-called Alfvén cascades have been investigated in the central regions of the discharge.

scholarly journals Instabilities of Magnetic Fields in Stars

1974 ◽  
Vol 59 ◽  
pp. 177-177
Author(s):  
R. J. Tayler
Keyword(s):  
Magnetic Field ◽  
Gravitational Potential ◽  
Rotation Period ◽  
Region Of Interest ◽  
Alfven Wave ◽  
Closed Field ◽  
Toroidal Plasma ◽  
Wide Range ◽  
Field Lines ◽  
Rotating Star

It has been shown (Markey and Tayler, 1973; Tayler, 1973; Wright, 1973) that a wide range of simple magnetic field configurations in stars are unstable. Although the ultimate effect of the instabilities is unclear, it seems likely that they would lead to enhanced destruction of magnetic flux, so that magnetic field decay would be much more rapid than previously supposed. Instability is almost certain in a non-rotating star containing either a purely toroidal field or a purely poloidal field, which has closed field lines inside the star. In both cases the instability resembles the well known instabilities of cylindrical and toroidal current channels, modified by the constraint that motion must be almost entirely along surfaces of constant gravitational potential.If both toroidal and poloidal fields are present, the problem is more complicated. In a toroidal plasma with a helical field, the worst instabilities are also helical but it is impossible for a helical disturbance to be parallel to a surface of constant gravitational potential everywhere. As a result, the admixture of toroidal and poloidal fields has a stabilizing influence, but it is not at present clear whether the majority of such configurations are completely stable.The effect of rotation has not yet been studied but it will certainly be important if the rotation period is less than the time taken for an Alfvén wave to cross the region of interest. This is true in most stars unless the internal magnetic field is very much stronger than any observed field.

Microtubule modulation of biliary excretion of endogenous and exogenous hepatic lysosomal constituents

1984 ◽  
Vol 246 (1) ◽  
pp. G8-G15 ◽  
Author(s):  
R. B. Sewell ◽  
S. S. Barham ◽  
A. R. Zinsmeister ◽  
N. F. LaRusso
Keyword(s):  
Lysosomal Enzyme ◽  
Biliary Excretion ◽  
Lysosomal Enzymes ◽  
Male Rats ◽  
Enzyme Secretion ◽  
Initial Increase ◽  
Acute Administration ◽  
Subsequent Decrease ◽  
Before And After

We tested the hypothesis that hepatocyte microtubules modulate the biliary excretion of endogenous and exogenous constituents of hepatocyte lysosomes. We collected bile via bile fistulas from male rats before and after acute administration of colchicine and vinblastine, agents known to bind to hepatocyte microtubules; rats were then killed and livers were homogenized for biochemical analyses or processed for electron microscopy. Colchicine caused biphasic, parallel alterations in the biliary excretion of three lysosomal enzymes compared with control rats given saline or lumicolchicine; a peak rise in enzyme outputs of approximately 175% at 45-60 min after colchicine administration was followed by a sustained fall to approximately 25% of control values, which persisted for 2-4 h. When hepatocyte lysosomes were prelabeled in vivo by administration of [3H]Triton WR-1339, a nonionic detergent that is sequestered in hepatic lysosomes, the biliary excretion of radiolabel in response to colchicine paralleled the biliary excretion of the three lysosomal enzymes. Vinblastine also induced a biphasic response in biliary lysosomal enzyme output that was similar to that produced by colchicine administration. Morphometric analysis of electron micrographs of rat livers demonstrated changes in the number of lysosomelike vesicles in the vicinity of bile canaliculi after colchicine and vinblastine administration; the initial increase in lysosomal enzyme secretion was associated with a significant decrease in the number of pericanalicular lysosomes after both agents, while the subsequent decrease in enzyme secretion coincided with an increase in the number of pericanalicular lysosomes after vinblastine.(ABSTRACT TRUNCATED AT 250 WORDS)

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