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Plasma cleaning manufacturer plasma wave mode

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18 Mar,2021

Plasma cleaning manufacturer plasma wave mode:
The wave patterns in plasma are very complicated. It includes transverse waves (wave vector k perpendicular to the electric field E) and longitudinal waves (k parallel to E) as well as non-transverse and non-longitudinal waves. These include elliptically polarized waves, circularly polarized waves and linearly polarized waves. The phase velocity of the wave can be greater than or equal to or less than the speed of light in vacuum C. The wave group velocities and phase velocities may be parallel, nonparallel, or antiparallel.

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Since charged particles in the plasma can influence wave propagation through the electromagnetic field of the wave, waves can take many forms. Under the action of external magnetic field, the wave form, magnetic field disturbance and particle motion affect each other, making the wave shape more complex. For example, the separation of positive and negative charges creates an electrostatic field with a Coulomb force as a restoring force, resulting in a Langmuir wave. The bending of the magnetic field line, its tension is the restoring force, resulting in the Alwyn wave; Various gradients in the plasma, such as density gradient and temperature gradient, will cause drift motion, which can be coupled with the wave mode to produce drift wave. Waves can be divided into cold plasma and hot plasma waves.


When the thermal velocity of the particle is much less than the wave velocity and the cyclotron radius (magnetized plasma) is much less than the wavelength, it is called cold plasma. The wave phenomenon of the particle is studied by magnetohydrodynamics method. A wave in an uncooled iso-body has a light wave whose velocity is greater than the speed of light C in a vacuum. In the case of magnetic plasma, which is anisotropic, the permittivity becomes a tensor. Just as there are two waves in other anisotropic media, there are also two types of waves in magnetized cold plasmas: ordinary and unusual.


When the refractive index of the plasma is n=0, the wave is truncated and reflected. When n→∞, the wave reacts with the resonant particle and is absorbed by the particle. For example, when the wave vector k is parallel to the external magnetic field, an unusual wave of frequency w= WCe will resonate with electrons whirring around the magnetic field, while a normal w= WCi wave will resonate with cyclotron ions, which are the cyclotron frequencies of electrons and ions respectively. In this case, the wave energy is absorbed and cyclotron damping is formed.


For hot plasmas, the thermal motion of particles and the finite cyclotron radius introduce new modes and effects. In addition to light waves, there are electron Langmuir waves and ion sound waves in the unmagnetized thermal plasma. A Langmuir wave resonates with an electron with a similar velocity, creating Landau damping. A wave in a magnetized thermal plasma characterized by a frequency w=lwce(l=0,1,2,3...) for reasons such as the Doppler effect. And w= lWCi (l=0,1,2...). The anomalous wave of... will resonate with cyclotron ion, resulting in Cherenkov and cyclotron damping.


In the inhomogeneous plasma, apart from the drift wave, different wave types can be converted to each other under certain conditions, such as extraordinary wave can be converted to normal wave or compressional wave. Shock waves, collisionless shock waves and solitary waves are nonlinear waves. When nonlinear effects are taken into account, different waveforms can be converted to each other or excited by each other, and compressional waves can be excited by shear waves. Wave theory not only studies the relation of dispersion, but also studies the interaction between wave and wave in plasma and wave and particle in plasma.

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