Coherent Structure Transport (SCT) Model in GEM-X

Understanding the energy deposition on the material surfaces is critical for fusion reactor design. Here, we utilize the GEM-X gyrokinetic simulation along with SOLPS-ITER solutions for the background equilibrium electric field to model the heat flux at the divertor plate and characterize the heat load width using realistic X-point geometry. We use a theory-based blobby transport model we call the coherent structure transport (CST) model. The CST model is extremely fast and can be used to quickly analyze any SOLPS-ITER solution. SOLPS-ITER provides the steady state, or equilibrium E-field on which we superimpose blobs characterized by size and amplitude. We then utilize the GEM-X gyrokinetic particle simulation to study the heat flux at the divertor plate(s). We obtain the 1/B_p scaling of the heat load width in agreement with theory in the equilibrium magnetic field. When including blobs in the SOLPS-ITER field, we show qualitative agreement with experiment for λ_q calculated using typical blob characteristics. We will describe the CST model in detail and investigate the scaling of λ_q with blob parameters.