Poloidal Distribution Of Penalty Factors For Demo Single Module Segment With Limiters In Normal Operation

The charged particle heat load expected for the DEMO Single Module Segment first wall (FW) during current off normal plasma scenarios indicates that protection is needed for avoiding/reducing damage to the breeding blanket FW due to the deposition of a huge amount of energy in a small timescale [1]. Within the EUROfusion framework of heat load analysis and design of DEMO wall and FW protections during plasma transients (identified as ?Key Design Integration Issue 1? [2]), extensive reworking has led to FW and limiter designs that keep the flat-top maximum heat load on both the FW and limiter plasma-facing surfaces within engineering limits. The limiter strategy appears promising for both normal and off-normal plasma events, therefore the study will be focussed on a FW equipped with limiters. As a continuation of the work started in [3], which has highlighted the weakest point of the older FW design and led to the new FW layout, the impact of misaligned segments and limiters on the charged particle heat flux pattern is investigated for the ?limited? FW (i.e. FW protected by limiters). The study is carried out by 3D field line tracing codes SMARDDA/PFCflux [4,5] and covers normal operation scenarios (ramp-up and steady-state) with the aim of producing heat flux penalty factor distribution to identify the worst case scenarios. As far as the normal transient events are concerned, the results in [3] are updated. In addition, during steady-state operation, deformation of in-vessel components due to mechanical loads such as ferromagnetic forces acting on EUROfer and different thermal expansion of adjacent segments, leads to the exposure of edges that are shadowed in the FW undeformed configuration. As a novel approach, flexible geometrical transformations simulating this kind of normal operation misalignment are implemented for studying the impact on the charged particle heat load of the induced differential deformations.