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Thompson Scattering
Description: A method of measuring the temperature and density of a plasma via the interaction between electro-magnetic radiation and matter
Recommended Product: Quantel YG980
Thomson scattering is a laser measurement technique that relies on the interaction between electro-magnetic radiation and matter.
It is a useful remote measurement method for determining the temperature and density of, for example, a plasma where due to the high temperatures and other restrictions, direct measurement techniques cannot be used.
By using a laser to illuminate a plasma, the E-vector of the incident laser beam causes the electrons in the plasma to move and oscillate at the same frequency as the laser.
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The oscilliating electron is then a dipole radiation source with its radiation being emitted in a donut shape.
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By measuring the emitted radiation, one can plot a graph of intensity versus wavelength, where the full width half maximum is proportional to temperature and the area under the curve is proportional to the density.
We recently supplied a custom-built Nd:YAG laser to JET for their High Resolution Thomson Scattering project. The specification of this laser was as follows:
| Wavelength
Energy Pulse duration Repetition rate Polarisation ratio |
1064nm
5J ~15ns 20Hz >98% |
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