Temperature thresholds for enhanced impurity production at carbon walls have been measured in TFTR (1650 ± 150 degrees C) and JET (1850 degrees C) and calculated (1900 degrees C). Precise knowledge of these thresholds is important not only for impurity control in a reactor but also for finding causal relationships among the changes in various parameters (line and continuum emission, radial distributions of densities and temperatures, confinement times, neutron yield and energy content) that occur somewhat simultaneously with a decline in discharge quality that sets in after auxiliary heating has been maintained for some time.
Impact of carbon impurities on the confinement of high-ion-temperature discharges in the Large Helical Device
Evidence of hot spot formation on carbon limiters due to thermal electron emission