Inductively Coupled Plasmas

This study investigates the transition mechanism from E-mode to H-mode in inductively coupled plasma (ICP) systems by employing a two-dimensional implicit electrostatic particle-in-cell/Monte Carlo collision (PIC/MCC) simulation. By self‑consistently computing the coil‑inductance–induced potential difference, we reconstruct the capacitive electric field generated by the coil and thus simulate the E–H mode conversion process. We analyze electron density, energy, potential distributions, and heating dynamics across a range of inductive coupling powers, identifying a critical transition window characterized by a rapid rise in plasma density and a shift in the electron energy probability distribution function (EEPF) from a bi‑Maxwellian to a single Maxwellian form. In E‑mode, capacitive coupling dominates: sheath‑oscillation heating produces pronounced nonuniformities in electron density and energy. As power increases, inductive coupling prevails, facilitating efficient ionization via high‑energy electrons and homogenizing plasma parameters. In H‑mode, inductive heating becomes the principal mechanism, mitigating sheath effects and, through enhanced electron collisions, promoting energy redistribution. These findings clarify the kinetic pathways underpinning the E–H mode transition and its associated heating processes, offering a theoretical foundation for optimizing ICP operation.

Funding acknowledgement

This work was supported by the National Magnetic Confinement Fusion Energy Research Project (2022YFE03190300) and the National Natural Science Foundation of China (12275095, 11975174 and 12011530142).