Evaporation and vapor shielding of CFC targets exposed to plasma heat fluxes relevant to ITER ELMs

Experimental verification of FOREV-2D simulations for the plasma shield

“…1. However, all the measurements are matching with the simulations if one assumes the effective thermoconductivity approximately three times lower [6]. Further simulations of these experimental results using the FOREV-2D code confirmed this conclusion.…”

“…For investigation of plasma shielding effect a series of the dedicated experiments have been performed in the MK-200UG facility and the results are reported in [6]. First analysis of the surface temperature measurements of the NB31 target in the MK-200UG facility have been performed and revealed that the measurements are definitely incompatible with the reference thermoconductivity of NB31 CFC [7,8] shown in Fig.…”

“…A series of dedicated experiments has revealed that vaporization from the heated CFC surface starts at total energy load of 0.17 MJ/m 2 providing the carbon plasma density of 2-3 Â 10 22 m À3 at the distance of few millimetres above the surface [6]. At the heat load of 0.2 MJ/m 2 the vapour density close to the surface increases 10 times and remains almost unchanged due to shielding of the surface from the hot hydrogen plasma.…”

“…The reason for the thermoconductivity degradation (described in [10]) is the large number of cracks developed in the layer of 100-200 lm thickness at the CFC surface in course of several hundred severe thermal shocks, performed before the surface temperature measurements for simulation of the ELM-like heat loads. The dependence of the energy absorbed by the target on the applied energy has been measured in the MK-200UG facility and reported in [6]. Simulations of these measurements have been performed using the FOREV-2D code.…”

Multi‐level model of radiation transport in inhomogeneous plasma

“…Another example of the radiation transport role is shielding effects, Transient events such as type‐I ELMs or disruptions bring enormous heat loads of the order of several GW/m 2 to the first wall components and especially to the divertor . Such heat loads induce melting and evaporation of the first wall materials.…”