Lecture

Classical Transport in Plasmas

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Description

This lecture covers classical transport in plasmas, focusing on random walks and diffusion processes in both un-magnetized and magnetized plasmas. The instructor explains the proof of diffusive transport, ambipolar diffusion, and classical diffusion of particles and heat. The lecture also delves into the derivation of the diffusion coefficient and the meaning of D in different plasma scenarios. Various equations and simulations are used to illustrate the concepts, including the impact of characteristic frequencies and collision frequencies on transport phenomena. The discussion extends to the generation of ambipolar electric fields and the implications for particle and heat diffusion in plasma.

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Plasma Physics: Applications

This physics course, taught by world-renowned experts in the field, will provide you with an overview of applications in plasma physics. From the study of far distant astrophysical objects, over diverse applications in industry and medicine, to the ultimate goal of sustainable electricity generation from nuclear fusion. In the first part of this course, you will learn how nuclear fusion powers our Sun and the stars in the Universe. You will explore the cyclic variation of the Sun’s activity, how plasma flo

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Related concepts (32)

Molecular diffusion

Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles. Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration. Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules.

Diffusion

Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential. It is possible to diffuse "uphill" from a region of lower concentration to a region of higher concentration, like in spinodal decomposition. Diffusion is a stochastic process due to the inherent randomness of the diffusing entity and can be used to model many real-life stochastic scenarios.

Convection–diffusion equation

The convection–diffusion equation is a combination of the diffusion and convection (advection) equations, and describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to two processes: diffusion and convection. Depending on context, the same equation can be called the advection–diffusion equation, drift–diffusion equation, or (generic) scalar transport equation.

Fick's laws of diffusion

Fick's laws of diffusion describe diffusion and were first posited by Adolf Fick in 1855 on the basis of largely experimental results. They can be used to solve for the diffusion coefficient, D. Fick's first law can be used to derive his second law which in turn is identical to the diffusion equation. A diffusion process that obeys Fick's laws is called normal or Fickian diffusion; otherwise, it is called anomalous diffusion or non-Fickian diffusion.

Temperature

Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called centigrade), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes.

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