Princeton University Astroplasmas Seminar

The movement and thermalization of turbulent energy between scales in plasmas is both fundamentally interesting and important for a wide range of modelling applications. In strongly magnetized space plasmas, energy in electromagnetic fluctuations is usually assumed to flow to the smallest scales, eventually heating electrons. During this talk I will show that when turbulence is dominated by outward-propagating perturbations, as occurs in the solar wind, the energy hits a “barrier” near the iongyroradius scale. The effect violates the “zeroth law of turbulence,” which states that large-scale turbulent statistics are independent of microphysical dissipation, suggesting interesting implications for plasma thermodynamics. It also provides a testable explanation for the long-standing puzzle of what determines the scale and slope of the “ion-kinetic transition” in observed magnetic- energy spectra.