Ion cyclotron emission studies: Retrospects and prospects

Abstract

Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfvenic cyclotron instabilities with the linear growth rate ~ $\sqrt {n_\alpha /n_e } $ driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. More recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusion devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. We discuss further prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.