Speaker
Description
The synergy between neutral beam injection (NBI) and ion cyclotron range of frequencies (ICRF) heating provides an effective route for tailoring fast-ion distribution functions and enhancing non-thermal fusion reactivity in tokamak plasmas. In this work, NBI–ICRF synergistic fast-ion physics in an EAST plasma scenario is investigated using complementary TRANSP and PTC simulations. NBI-only and combined NBI–ICRF cases are compared in terms of fast-ion inventory, mean-energy and density profiles, energy–pitch-angle distributions, neutron production channels, and synthetic neutron spectra along selected lines of sight. TRANSP is used to evaluate fast-ion sources, NBI deposition, RF power absorption, and thermal, beam–thermal, and beam–beam neutron components, while PTC is employed to resolve the orbit-level phase-space evolution of resonant beam ions.
The simulations show that ICRF wave–particle interaction selectively accelerates resonant NBI-born ions, broadens the fast-ion energy distribution, and forms a pronounced high-energy tail. The resulting changes in pitch-angle distribution and real-space localization modify the relative contributions of different neutron production channels and lead to measurable changes in line-of-sight-resolved neutron spectra. These responses are attributed to RF-driven beam-ion acceleration, velocity-space anisotropy, and finite-orbit-width effects. Sensitivity scans of the cyclotron-resonance-layer position, antenna-launched parallel wave number, and NBI beam tangency radius further clarify how heating geometry controls RF absorption by beam ions and the associated neutron enhancement. The combined TRANSP–PTC analysis establishes a simulation framework linking beam-ion seed formation, resonance-selective RF acceleration, fast-ion phase-space reconstruction, and neutron diagnostic signatures, supporting the interpretation and optimization of NBI–ICRF synergy experiments on EAST.