File:DEMO fusion reactor Bfield surfaces.png

English: Poloidal cross-section of a tokamak plasma for DEMO with a single magnetic null divertor configuration, illustrating the regions of the plasma and the boundary walls where important PMIs and atomic physics processes take place. The characteristic regions are: (i) the plasma core, (ii) the edge region just inside the separatrix, (iii) the scrape-off-layer (SOL) plasma outside the separatrix, and (iv) the divertor plasma region, which is an extension of the SOL plasma along field lines into the divertor chamber. The baffle structure is designed to prevent neutrals from leaving the divertor. In the private flux region below the ‘X’ point, the magnetic field surfaces are isolated from the rest of the plasma.