Relevant heating of the quiet solar corona by Alfvén waves: a result of adiabaticity breakdown

International audienceIon heating by Alfvén waves has been considered for long as the mechanism explaining why thesolar corona has a temperature several orders of magnitude higher than the photosphere. Unfortu-nately, as the measured wave frequencies are much smaller than the ion cyclotron frequency, particleswere expected to behave adiabatically, impeding a direct wave-particle energy transfer to take place,except through decorrelating stochastic mechanisms related to broadband wave spectra. This paperproposes a new paradigm for this mechanism by showing it is actually much simpler, more general,and very efficient. Indeed, for measured wave amplitudes in the quiet corona, ion orbits are shownto cross quasi-periodically one or several slowly pulsating separatrices in phase space. Now, a sepa-ratrix is an orbit with an infinite period, thus much longer than the pulsation one. Therefore, eachseparatrix crossing cancels adiabatic invariance, and yields a very strong energy transfer from thewave, and thus particle heating. This occurs whatever be the wave spectrum, even a monochromaticone. The proposed mechanism is so efficient that it might lead to a self-organized picture of coronalheating: all Alfvén waves exceeding a threshold are immediately quenched and transfer their energyto the waves