Contribution of Cyclotron-resonant Damping to Kinetic Dissipation of Interplanetary Turbulence

We examine some implications of inertial range and dissipation rangecorrelation and spectral analyses extracted from 33 intervals of Wind magneticfield data. When field polarity and signatures of cross helicity and magnetichelicity are examined, most of the datasets suggest some role of cyclotronresonant dissipative processes involving thermal protons. We postulate that anactive spectral cascade into the dissipation range is balanced by a combinationof cyclotron-resonant and non-cyclotron-resonant kinetic dissipationmechanisms, of which only the former induces a magnetic helicity signature. Arate balance theory, constrained by the data, suggests that the ratio of thetwo mechanisms is of order unity. While highly simplified, this approachappears to account for several observed features, and explains why completecyclotron absorption, and the corresponding pure magnetic helicity signature,is usually not observed.Comment: With 1 figure; accepted by Astrophys. J. Lett., September 1, 199