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Thomson scattering is a model for the effect of electromagnetic fields on electrons when the field energy is much less than the rest mass of the electron .In the model the electric field of the incident wave accelerates the charged particle, causing it, in turn, to emit radiation at the same frequency as the incident wave, and thus the wave is scattered.
The classical electron radius appears in the classical limit of modern theories as well, including non-relativistic Thomson scattering and the relativistic Klein–Nishina formula. Also, is roughly the length scale at which renormalization becomes important in quantum electrodynamics. That is, at short-enough distances, quantum fluctuations ...
Scattering of laser light from the electrons in a plasma is known as Thomson scattering. The electron temperature can be determined very reliably from the Doppler broadening of the laser line. The electron density can be determined from the intensity of the scattered light, but a careful absolute calibration is required.
In some cases it is convenient to express the classical electron radius in terms of the Compton wavelength: = ¯ = /, where is the fine structure constant (~1/137) and ¯ = / is the reduced Compton wavelength of the electron (~0.386 pm), so that the constant in the cross section may be given as:
Consider the scattering of a beam of wavelength by an assembly of particles or atoms stationary at positions , =, …,.Assume that the scattering is weak, so that the amplitude of the incident beam is constant throughout the sample volume (Born approximation), and absorption, refraction and multiple scattering can be neglected (kinematic diffraction).
Such interaction between the light and free electrons is called Thomson scattering or linear Thomson scattering. [117] The relative strength of the electromagnetic interaction between two charged particles, such as an electron and a proton, is given by the fine-structure constant. This value is a dimensionless quantity formed by the ratio of ...
One of the criteria which determine whether a collection of charged particles can rigorously be termed an ideal plasma is that Λ ≫ 1.When this is the case, collective electrostatic interactions dominate over binary collisions, and the plasma particles can be treated as if they only interact with a smooth background field, rather than through pairwise interactions (collisions). [3]
Here ′ = is the wavevector inside the material, = / and the critical angle /, with the Thomson scattering length. Below the critical angle Q < Q c {\displaystyle Q<Q_{c}} (derived from Snell's law ), 100% of incident radiation is reflected through total external reflection , R = 1 {\displaystyle R=1} .