The Academy of Sciences of the Czech rebublic - ASCR

Divertor probes in COMPASS


Measured quantities:: Electron density, temperature and floating potential in divertor region
Spatial resolution: ~ 5 mm
Temporal resolution: 1 µs
Responsible person: R. Dejarnac
Collaboration: St. Kliment Ohridski University of Sofia, Bulgaria



Diagnostic description:

A Langmuir probe (LP) is a conducting wire, which is immersed into the plasma and to which a triangular shaped potential is applied. The quantities measured are the electron temperature and density, and the floating potential. The tokamak COMPASS is equipped with an array of 39 Langmuir probes embedded in the divertor tiles (see Fig. 1). A tokamak divertor is the part of the vessel where the main interactions of the hot plasma with the walls take place. Therefore, it is a strategic place to monitor for material heating purposes (plasma density and temperature lead to particle and power fluxes) and for heat transport studies.




Fig. 1: Photograph of the divertor Langmuir probes in COMPASS divertor region.


Measurements with the Langmuir probes are routinely performed for each discharge since the beginning of COMPASS operations in Prague.