Abstract
Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the fusion born alpha-particle
population in magnetically confined plasmas. Pioneering observations from JET and TFTR found
that ICE intensity P ICE scales approximately linearly with the measured neutron flux from fusion
reactions, and with the inferred concentration, n α /n i , of fusion-born alpha-particles confined within
the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling
for the first time. This resolves a longstanding question in the physics of fusion alpha particle
confinement and stability in MCF plasmas. It confirms the MCI as the likely emission mechanism
and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.