Effects of kinetic processes in shaping Io's global plasma environment: A 3D hybrid model

Abstract

Abstract. The global dynamics of the ionized and neutral components in the environment of Io plays an important role in the interaction of Jupiter's corotating magnetospheric plasma with Io. The stationary simulation of this problem was done in the MHD and the electrodynamics approaches. One of the main significant results from the simplified two-fluid model simulations (Saur et al., 2002) was a production of the structure of the doublepeak in the magnetic field signature of the I O flyby that could not be explained by standard MHD models. In this paper, we develop a method of kinetic ion simulation. This method employs the fluid description for electrons and neutrals whereas for ions multilevel, drift-kinetic and particle, approaches are used. We also take into account charge-exchange and photoionization processes. Our model provides much more accurate description for ion dynamics and allows us to take into account the realistic anisotropic ion distribution that cannot be done in fluid simulations. The first results of such simulation of the dynamics of ions in the Io's environment are discussed in this paper.

Nature of the iogenic plasma source in Jupiter's magnetosphereII. Near-Io distribution

“…For comparison with these mass loading rates for the Outer Region, new and improved estimates for the Inner Region are also summarized in Table 2. The major improvement of Inner Region rates in Table 2 occurs because they are now based upon newly available kinetic-ion hybrid model rates (Lipatov and Combi, 2005) which have replaced earlier adopted MHD model rates used to make estimates in Table 4 of Paper I. The earlier MHD model rates are now recognized to be a significant (factor of ∼2) overestimate due to their inability to include the pressure anisotropy effects of newly created pickup ions (Combi et al, 2002;Lipatov and Combi, 2005).…”

“…For the net-mass loading rate in Table 2, the new Inner Region estimate is 111-145 kg s −1 . The adopted lower value of 111 kg s −1 is that calculated by the kinetic-ion hybrid model simulations of Lipatov and Combi (2005) for their best and most-realistic model-fit to the Galileo spacecraft measurements for Io of the plasma and magnetic field along the downstream J0 pass and is essentially the same value (∼100 kg s −1 ) as independently estimated by Saur et al (2003). This adopted Inner Region estimated rate is appropriate since the model calculated rate of Lipatov and Combi (2005) is determined within a radial interval of 7 R Io about Io and is based upon a prescribed Io neutral density distribution that produces a net-mass loading rate that is almost entirely confined below our exobase radius of 2600 km.…”

“…The adopted lower value of 111 kg s −1 is that calculated by the kinetic-ion hybrid model simulations of Lipatov and Combi (2005) for their best and most-realistic model-fit to the Galileo spacecraft measurements for Io of the plasma and magnetic field along the downstream J0 pass and is essentially the same value (∼100 kg s −1 ) as independently estimated by Saur et al (2003). This adopted Inner Region estimated rate is appropriate since the model calculated rate of Lipatov and Combi (2005) is determined within a radial interval of 7 R Io about Io and is based upon a prescribed Io neutral density distribution that produces a net-mass loading rate that is almost entirely confined below our exobase radius of 2600 km. The adopted upper value of 145 kg s −1 is obtained by using the smaller and more realistic rate (see Paper I) of 188 kg s −1 given by Bagenal (1997) effectively for the Lagrange sphere volume and reducing it by the 43 kg s −1 calculated in this paper for the Outer Region contribution in the Lagrange sphere.…”

“…The neutral cloud model, which was presented in detail in Paper I and is only briefly discussed here in Section 2, will be used to calculate the instantaneous rates and spatial nature of the iogenic plasma source created by atomic oxygen and sulfur for the Outer Region, where the plasma may be regarded as essentially unperturbed above the generously adopted exobase radius of 2600 km and the neutral cloud model is valid. No spatial modeling but only comparative volumetric estimates will be made for the iogenic source rates that exist in the Inner Region where the atmosphere is collisional, the plasma and field conditions are expected to be strongly perturbed (Linker et al, 1998;Saur et al, 1999;Combi et al, 1998Combi et al, , 2002Lipatov and Combi, 2005), and the neutral cloud model is not valid. In Section 3, the model calculations for the three-dimensional distribution of the instantaneous pickup ion rates near Io in the Outer Region are presented.…”

1. Transport of Mass, Momentum and Energy in Planetary Magnetodisc Regions

“…However, these authors did not self-consistently solve for the magnetic field perturbation, but rather determined the perturbation based on the modeled currents. A hybrid simulation was also attempted by Lipatov and Combi (2006) to improve the treatment of mass loading and the related generation of non-Maxwellian pickup distributions. More recently, Dols et al (2012) used a MHD approach, coupled with mass loading rates determined from a physical chemistry model of the local Io interaction (Dols et al 2008).…”