Neutron production during current ramp-up in EAST under combined neutral beam injection and electron cyclotron resonance heating

The mechanisms of neutron production were investigated during the current ramp-up phase in EAST using a combination of neutral beam injection (NBI) and electron cyclotron resonance heating (ECRH). Simulation tools such as ONETWO and TRANSP are employed to model the evolution of neutron yields under dynamic operational conditions, including NBI and ECRH power injection, plasma current, and line-averaged electron density. The application of pure ECRH contributes to a minimal neutron yield, attributed to a limited increase in ion temperature. In contrast, the introduction of NBI substantially augments neutron yield, primarily through beam–target and beam–beam interactions. Simulations display a peak neutron yield of 9.8×10¹⁴ s^–1 for the current EAST NBI system, exceeding previous predictions due to enhanced heating efficiency. Simulations predict a 50% increase in total neutron yield upon implementation of the upgraded NBI system, characterized by 120 keV dual-source operation. The synergistic effect of NBI and ECRH on neutron yield was analyzed. Synergistic heating increased neutron yield by up to 3.2×10¹⁴ s^–1 at t = 4.8 s, primarily enhancing core-region emission. This work elucidates the underlying physics of neutron yield enhancement and provides critical insights into optimizing auxiliary heating scenarios for future fusion devices, shedding light on neutron emission and fusion reaction dynamics in next-generation fusion reactors.