Evidence for a link between turbulence and the generation of ion cyclotron waves via the helicity barrier effect in the solar wind

The dissipation and heating of collisionless plasma in the inner heliosphere is a significant unresolved problem in space physics. The helicity barrier theory suggests a possible mechanism for these processes, but it requires validation through analysis of spacecraft data. We assess the validity of the parameter regime associated with the helicity barrier in the solar wind over a range of heliocentric distances using Parker Solar Probe and Solar Orbiter. We use the Politano-Pouquet law to estimate the energy and cross helicity cascade rates in the solar wind and compare the values to radial distance, the polarisation and prevalence of ion cyclotron waves. We find that the amplitude and prevalence of left-hand-polarised waves in the solar wind is directly correlated with the total energy and the cross helicity cascade rate of the turbulence. Our measurements are consistent with the helicity barrier being active in all solar wind intervals that we study and we demonstrate the uncertainty in calculating energy and the cross helicity cascade rates in this study.