Novel Technique for Direct Measurement of the Plasma Diffusion Coefficient in Magnetized Plasma

2008 ◽  
Vol 48 (5-7) ◽  
pp. 418-423 ◽  
Author(s):  
J. Brotánková ◽  
E. Martines ◽  
J. Adámek ◽  
J. Stöckel ◽  
G. Popa ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Direct Measurement ◽  
Magnetized Plasma ◽  
Novel Technique ◽  
Plasma Diffusion

scholarly journals The mobility of sodium on tungsten

1935 ◽  
Vol 150 (869) ◽  
pp. 58-76 ◽  
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Work Function ◽  
Direct Measurement ◽  
Diffusion Coefficients ◽  
Condensation Coefficient ◽  
Alkali Earth ◽  
Adsorbed Films ◽  
A Value ◽  
Two Phases

Although the existence as well as some of the properties of adsorbed films of alkali and alkali earth metals on metals of higher work function have long been known, it is only recently that these films have been shown to be capable of migrating over the surface of the adsorbent, and that attempts have been made to measure diffusion coefficients and the activation energy associated with the diffusion. Langmuir and Taylor, investigating the properties of cæsium films, found it necessary to postulate that the cæsium was mobile in order to account for the high value (α ≅ 1.0) for the condensation coefficient on quite concentrated films. Later they were able to make a direct measurement of the diffusion coefficient. They obtained a value of D at 812° K of 3.4 x 10 -5 cm 2 secs -1 , and an activation energy of 0.61 volt. Langmuir has also shown that cæsium films exist in two phases and has measured the diffusion coefficient by following the movement of the boundary between these two phases.

Ambipolar Drift, Deformation, and Diffusion of a Plasma in a Magnetic Field

1973 ◽  
Vol 51 (5) ◽  
pp. 564-573 ◽  
Author(s):  
Richard L. Monroe
Keyword(s):  
Magnetic Field ◽  
Diffusion Coefficient ◽  
Effective Magnetic Field ◽  
Theoretical Problem ◽  
Direction Parallel ◽  
Transverse Diffusion ◽  
Weakly Ionized ◽  
Plasma Diffusion ◽  
Ambipolar Drift ◽  
And Diffusion

The theoretical problem of a weakly ionized, constant temperature, three particle plasma in an externally generated magnetic field is reformulated by transforming the set of 14 macroscopic plasma equations (continuity and momentum equations for ions and electrons plus Maxwell's equations) in 14 unknowns (ion and electron number densities and velocities plus the effective electric and magnetic fields) into an equivalent set of 4 integral equations in 4 unknowns. In the course of this transformation, it is shown that the plasma behavior can be interpreted in terms of three ambipolar processes : drift, deformation, and diffusion. Plasma diffusion is characterized by two diffusion coefficients : the usual Schottky formula applying in the direction parallel to the effective magnetic field and a new expression for the ambipolar transverse diffusion coefficient applying in directions perpendicular to the effective magnetic field. The new ambipolar coefficient differs markedly from the familiar ambipolar coefficient associated with the names of Bickerton, Lehnert, Holway, Allis, and Buchsbaum; and, in general, it gives values for the transverse diffusion coefficient which are two orders of magnitude larger than those given by the latter. It is concluded that ambipolar diffusion can produce a transverse diffusion coefficient large enough to account for the diffusion rates measured by Bohm, Burhop, Massey, and Williams in argon arc discharges.

Different techniques for investigation of plasma diffusion coefficient in IR-T1 Tokamak

2017 ◽  
Author(s):  
Mahmood Ghoranneviss ◽  
Sakineh Meshkani ◽  
Mansoureh Lafouti
Keyword(s):  
Diffusion Coefficient ◽  
Plasma Diffusion

Das passive Problem der anomalen Plasma-Diffusion / The Passive Problem of Anomalous Plasma Diffusion

1982 ◽  
Vol 37 (8) ◽  
pp. 785-794
Author(s):  
Klaus Elsässer
Keyword(s):  
Diffusion Coefficient ◽  
Turbulent Convection ◽  
Magnetic Fluctuations ◽  
Correlation Lengths ◽  
Toroidal Plasma ◽  
Ensemble Mean ◽  
Plasma Diffusion ◽  
Order Of Magnitude ◽  
Two Space Dimensions ◽  
Perturbative Treatment

The diffusion of magnetic lines of force in a toroidal plasma is equivalent within a perturbative treatment, to the problem of turbulent convection in two space dimensions. Neglecting a triplecorrelation the diffusion coefficient D is, therefore, given as a spectral and ensemble mean of the Green’s function, and the following order of magnitude is obtained:Dxx ≈ Min(L0 |B̃x|2/B02, l0\B̃x\/B0),where L0 and l0 are the (Eulerian) correlation lengths of the magnetic fluctuations B̃ parallel and perpendicular to the unperturbed field B0, respectively

scholarly journals Novel technique to measure mutual bulk fluid diffusion using NMR 1-D gradient

2020 ◽  
Vol 146 ◽  
pp. 03007
Author(s):  
Son Dang ◽  
Carl Sondergeld ◽  
Chandra Rai
Keyword(s):  
High Pressure ◽  
Porous Media ◽  
Diffusion Coefficient ◽  
Effective Diffusion ◽  
Hydrogen Index ◽  
Accurate Estimation ◽  
Bulk Fluid ◽  
Novel Technique ◽  
Small Pore ◽  
Fluid Diffusion

Many modelling and theoretical studies have shown that diffusion can be a significant transport mechanism in low-permeability porous media. Understanding the process allows engineers to better predict reservoir performance during both primary production and enhanced recovery in unconventional reservoirs. Direct measurement of effective diffusion in tight rocks is difficult, due to small pore volumes and the lack of techniques to actually monitor the process. Conventional diffusion measurements generally require fluid sampling, which induces a pressure transient which changes the mass transfer mechanism. Previously, we introduced a novel technique to measure tortuosity in nano-porous media by simultaneously monitoring methane versus nitrogen concentrations at high pressure using transmission Infrared Spectroscopy (IR). To complete the estimation of effective diffusion, bulk fluid diffusion coefficient also needs to be measured. In this study, we demonstrate the usage of Nuclear Magnetic Resonance (NMR) 1-D imaging to examine the dynamic change of Hydrogen Index (HI) across the interface between two bulk fluids. The experiment was conducted between a crude oil sample and methane; fluid samples were pressurized within an NMR transparent ZrO2 pressure cell which operates at pressures up to 10,000 psi. The Hydrogen Index (HI) profile was continuously measured and recorded for 7 days. The results provided oil the swelling factor and the concentration profile as a function of both time and distance. These data then were fitted with Maxwell-Stefan equation to precisely back calculate the diffusion coefficient between oil and gas samples at high pressure. Accurate estimation of tortuosity and fluid diffusion is critical for the gas injection strategy in a shale formation. Greater tortuosity and smaller fluid diffusion rate lead to longer injection and production times for desirable economic recovery.

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