Polarimetric Thomson scattering measurements in 1 JET high Temperature Plasmas

Polarimetric Thomson scattering measurements in 1 JET high Temperature Plasmas

Polarimetric Thomson scattering measurements in 1 JET high Temperature Plasmas 150 150 UKAEA Opendata
UKAEA-CCFE-PR(22)52

Polarimetric Thomson scattering measurements in 1 JET high Temperature Plasmas

Thomson scattered light is polarised in the same orientation as the incident laser beam at low electron temperatures. At high temperatures (>~4keV) part of the spectrum begins to become randomly polarised. First measurement of the depolarised Thomson scattering spectrum during were obtained from JET pulses 92038-92504. This paper builds upon these initial measurements with new measurements obtained from 99147-99735. These new measurements improve upon first results, in particular by obtaining spectral measurements of the depolarised spectrum. The recent JET campaign was well suited to these measurements with long and hot plasmas. The resulting data are averaged over many plasmas and laser pulses to obtain a measurement of the amount of ‘p‘ and ‘s‘ scattered light as a function of electron temperature. This experimentally obtained ‘p/s‘ ratio versus Te is then fitted and found to show very good agreement with the theoretically predicted depolarised fraction. Error estimates on the measured ‘p/s‘ have been obtained and show that the measurements are meaningful. This is good news for ITER which plans to use this measurement as a check on the Te determined by the core plasma Thomson scattering diagnostic by conventional spectral measurement techniques.

Collection:
Journals
Journal:
Review of Scientific Instruments
Publisher:
AIP (American Institute of Physics)