Investigation of electron cyclotron wave absorption and current drive in CFEDR conventional H-mode scenario

The electron cyclotron (EC) wave absorption and current drive, which play an important role in current profile control and neoclassical tearing mode (NTM) suppression, were investigated for the China Fusion Engineering Demo Reactor (CFEDR) conventional H-mode scenario using the TORAY code. To achieve the physics goal of the EC system in CFEDR, the influence of EC wave frequency and launching positions on the absorption and current drive performance was considered, and the injection poloidal and toroidal angles were scanned systematically. The electron cyclotron current drive (ECCD) efficiency at the plasma center and ρ = 0.35 of launching points A1 and A2 in the equatorial port increases with the EC frequency up to 235 GHz and then starts to decrease. For the launching point B1 in the upper port, the ECCD efficiency exhibits a saturation trend above an EC frequency of 200 to 250 GHz. For current profile control at ρ ~ 0.35, the ECCD efficiency of launching points A1 and A2 in the equatorial port is close to that of B1 in the upper port when the frequency is lower than 235 GHz. For NTM control, the launching points in the upper port have a smaller beamwidth and larger driven current, which means that the performance of the launching points in the upper port is better than that of the equatorial port. This study provides theoretical guidance for the design of an EC resonance heating system on CFEDR, and has important significance for the physical design of CFEDR.