Elucidating the ion heating mechanism in hybrid simulations of the Kelvin-Helmholtz instability �

P. A. Delamere¹, J. R. Johnson², P. A. Damiano¹, C. S. Ng¹, X. Ma³, K. Nykyri³

^{1. University of Alaska Fairbanks, 2. Andrews University, 3. Embry-Riddle Aeronautical University.}

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Introduction and motivation

• How is plasma heated in giant planet magnetodiscs?
• Turbulent heating during radial transport -> nonlinear interaction between counter propagating kinetic Alfven waves [Saur, 2004; von Papen et al., 2014; Tao et al., 2015; Kaminker et al., 2017; Ng et al., 2018].
• Simple analytical expressions for heating rate density are confirmed with 3-D Kelvin-Helmholtz hybrid simulations [Delamere et al., 2020].
• But what is the heating mechanism?
• Johnson and Cheng [2001] suggest stochastic ion heating.
• Investigate the onset and nature of stochasticity in the context of 3-D Kelvin-Helmholtz simulations.

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Bagenal and Delamere [2011]

3-D hybrid KH simulations

Delamere et al., 2018

Kinetic Alfven waves (KAW)

Delamere et al., 2018

Heating rate density

KH Hybrid simulation: Heating rate density

Stochastic heating

Onset of stochasticity: hybrid simulation

Nonconservation of magnetic moment

Case study

Velocity distribution functions

Initial

Final

KH-related heating at Saturn

Burkholder et al., 2019

Zhang et al., 2018

Radial transport and turbulent heating

• Advective and diffusive transport with a turbulent heating source term.

Ng et al., 2018; Neupane et al., 2020; Ng et al., 2021

Jupiter

Saturn

Conclusions