The local electron density and temperature in a plasma on the COMPASS tokamak have been measured using Thomson scattering diagnostic based on measurement of both intensity and spectra of a laser light scattered by plasma electrons.
Two diagnostic ports have been used for the Thomson scattering diagnostic: one oriented towards the plasma core and one towards the plasma edge. However, until recently it was not possible to cover the whole edge plasma region in several important operational scenarios due to geometrical constraints of the existing edge port. In order to optimise the field of view and to enable observation of the whole edge plasma region, the edge port had to be modified.
To this end, a new edge port design was prepared in IPP Prague. After challenging and detailed preparations, which included experimental laser cutting of material samples and test modification made on full size COMPASS vessel mock-up, the tokamak port was modified by a specialised company in June 2016. Within 30 hours the original port was cut out, the new port with larger diameter and favourable orientation was welded in place, and the tokamak vacuum pumping was resumed. After the necessary standard wall conditioning, including the vacuum vessel baking, the tokamak got ready again for the standard operation.
The video you can see below:
22 Jun 2016
