A comprehensive numerical simulation of Io’s sublimation-driven atmosphere

Walker, Andrew; Gratiy, Sergey L.; Goldstein, David; Moore, Chris H.; Varghese, Philip L.; Trafton, Laurence M.; Levin, Deborah A.; Stewart, B. D.

doi:10.1016/j.icarus.2010.01.012

Cited by 56 publications

(52 citation statements)

References 63 publications

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“…2-D computational work on Io's atmosphere has modeled Io's steady-state atmosphere including crude plasma heating [5] and plasma chemistry models that have found a dayside SO/SO 2 ratio of 3-7% [6], consistent with an observed ratio of 1-10% [7]. More recent 3-D DSMC simulations of Io's atmosphere [8] improved on previous simulations by using a complex surface temperature and frost fraction model but still used a simple plasma heating model without chemistry. The present work aims to investigate the vertical structure and composition of Io's atmosphere by incorporating an improved plasma model that includes resonant charge exchange [9], electron elastic, ionization, and dissociation collisions [10], and MD/QCT dissociation cross sections [1,11] for fast neutrals.…”

Section: Introductionmentioning

confidence: 75%

“…The resultant atmosphere was simulated by a one-dimensional multi-species model using the DSMC method [13]. The general details of the code and its application are discussed in previous papers [4,5,8,14,15]. It includes an SO 2 sublimation rate based on the surface temperature, internal energy (rotation and quantized vibration) modes, and a collision limiter scheme to increase the computational efficiency in the near continuum regime.…”

Section: Modelmentioning

confidence: 99%

“…Since this diversion of the flow should reduce the plasma flux to lower altitudes, the current 1D simulations with charged particles offer an upper bound on the plasma's effect on Io's atmosphere and the simulations that only include fast neutrals offer a lower bound on the plasma effect. Future simulations in our 3D code [8] will incorporate the ambipolar field. In the current model we assume each electron's motion is linked to a corresponding ion [20] whose motion is effected by the Lorentz force and Io's gravity.…”

Section: Modelmentioning

confidence: 99%

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Simulation of Plasma Interaction with Io’s Atmosphere

Moore¹,

Deng²,

Goldstein³

et al. 2011

AIP Conference Proceedings

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Articles you may be interested inDevelopment of a chemistry model for DSMC simulation of the atmosphere of Io using molecular dynamics AIP Conf. Proc. 1501, 579 (2012) Abstract. One dimensional Direct Simulation Monte Carlo (DSMC) simulations are used to examine the interaction of the jovian plasma torus with Io's sublimation atmosphere. The hot plasma sweeps past Io at ~57 km/s due to the external Jovian magnetic and corotational electric fields and the resultant energetic collisions both heat and dissociate the neutral gas creating an inflated, mixed atmosphere of SO 2 and its daughter products. The vertical structure and composition of the atmosphere is important for understanding Io's mass loading of the plasma torus, electron excited aurora, and Io's global gas dynamics. Our 1D simulations above a fixed location on the surface of Io allows the O + and S + ions to drift down into the domain where they then undergo elastic and charge exchange collisions with the neutral gas. Each electron's position is determined by the motion of a corresponding ion; however, the electrons retain their own velocity components which are then used during elastic, ionization, and excitation collisions with the neutral gas. Charge exchange creates fast neutral O and S atoms. Molecular Dynamic/QuasiClassical Trajectory (MD/QCT) calculations are used to generate total and reaction cross sections for energetic O+SO 2 collisions [1] as well as for O+O 2 collisions. In addition, the model accounts for photo-dissociation assuming the atmosphere is optically thin. Our previous plasma heating model (without chemistry) agrees well with the vertical structure of the current model at lower altitudes where the gas is collisional; however, at high altitudes (>100 km) significant differences among the models appear. The current model's constant E and B fields results in reacceleration of the ions and electrons to a constant E×B drift velocity towards the surface after collisions with the neutral gas and, while the results are an upper limit on the plasma interaction strength, the results indicate that joule heating is significant, causing large changes in the vertical structure of the atmosphere. Plasma heating of, not momentum transfer to, the atmosphere dominates even for radially inward plasma flows resulting in a hot, inflated atmosphere. The scale heights for the various species were found to be a competition between the hydrodynamic scale height based on the gas constant (for the mixture if collisional) and the production rate from dissociation of SO 2 which depends on the local SO 2 density and available plasma energy at that altitude.

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Section: Introductionmentioning

confidence: 75%

Section: Modelmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

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Simulation of Plasma Interaction with Io’s Atmosphere

Moore¹,

Deng²,

Goldstein³

et al. 2011

AIP Conference Proceedings

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“…The same method has previously been used to simulate plumes evolving from round holes [3]. This planet-scale DSMC code has been developed over a number of years in our group [4,5,6].…”

Section: Modelmentioning

confidence: 99%

Simulating Irregular Source Geometries for Ionian Plumes

McDoniel¹,

Goldstein²,

Varghese³

et al. 2011

AIP Conference Proceedings

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Abstract. Volcanic plumes on Io respresent a complex rarefied flow into a near-vacuum in the presence of gravity. A 3D Direct Simulation Monte Carlo (DSMC) method is used to investigate the gas dynamics of such plumes, with a focus on the effects of source geometry on far-field deposition patterns. A rectangular slit and a semicircular half annulus are simulated to illustrate general principles, especially the effects of vent curvature on deposition ring structure. Then two possible models for the giant plume Pele are presented. One is a curved line source corresponding to an IR image of a particularly hot region in the volcano's caldera and the other is a large area source corresponding to the entire caldera. The former is seen to produce the features seen in observations of Pele's ring, but with an error in orientation. The latter corrects the error in orientation, but loses some structure. A hybrid simulation of 3D slit flow is also discussed.

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“…Density, temperature, and bulk velocity of the gas are recovered by averaging over the positions and velocities of the representative molecules. This model has been applied to many instances of rarified flow, including the expanding gas from a comet , the tenuous atmospheres of moons (Walker et al, 2010), and the spreading of a neutral torus around planets . used this method to model escape from Titan.…”

Section: Background'mentioning

confidence: 99%

Simulating Pluto's Atmosphere with Hybrid Fluid/Kinetic Models

Erwin

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Recent and planned spacecraft exploration of the planets and moons of our solar system have greatly increased interest in atmospheric escape. The Cassini spacecraft is currently improving our understanding of the upper atmosphere of Saturn's large moon Titan, in 2014 the Maven spacecraft will begin to orbit Mars to study its upper atmosphere and atmospheric loss, and in 2015 the New Horizons spacecraft will have a close flyby encounter with Pluto. My motivation has been to produce an accurate model of Pluto's atmosphere, which includes atmospheric loss by escape. The results will be both predictive for and tested against data obtained during the New Horizon encounter. By accurately describing the present loss rates, one can hope to eventually be able to extrapolate back in time in order to describe the long-term evolution of Pluto's atmosphere. Doing this accurately for a planet for which we will have in situ spacecraft data will then guide our ability to model atmospheres for a large number of exoplanets observed orbiting other stars for which there is only remote sensing data.Constraints on Pluto's atmosphere have been obtained through modeling and a few stellar occultation events in the last few decades. These have set a surface pressure range of 6.5-24 microbar of the primarily nitrogen atmosphere, with a methane mixing ratio of ~0.5%. Carbon monoxide has been detected as a trace species out to ~4 planetary radii, suggesting an atmosphere that is much more extended than predicted. Typically hydrodynamic models have been applied to describe escape from planetary bodies such as Pluto and Titan. Such models require solving the fluid equations out to very large distances from the planet in order to enforce boundary conditions. However, it is known ii through molecular kinetic simulations that at some finite distance above the surface the fluid equations fail to describe the gas properties accurately as the atmosphere transitions into the largely collisionless exosphere. To accurately capture the nature of the escape and structure of Pluto's thermosphere and exosphere, I have developed a model of Pluto's upper atmosphere by connecting a fluid model, using radiative heating models relevant for the thermosphere and stratosphere, to a molecular kinetic model. Using this hybrid model I have shown that the atmosphere is much more extended than previously predicted and the escape is not supersonic, as in comet or stellar atmospheres. Rather, it is closer to the evaporative Jeans model of escape.Pluto's lower atmosphere or upper atmosphere have typically been modeled separately, without considering the interactions between these two regimes. Therefore, Ihave developed a self-consistent model of Pluto's full atmosphere, including both the stratospheric radiative heating and cooling that prevail in the lower atmosphere, as well as the UV heating and the cooling by atmospheric escape. These reach a sensitive balance in the upper atmosphere. The stratospheric processes included non-LTE IR radiative heating and cooli...

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A comprehensive numerical simulation of Io’s sublimation-driven atmosphere

Cited by 56 publications

References 63 publications

Simulation of Plasma Interaction with Io’s Atmosphere

Simulation of Plasma Interaction with Io’s Atmosphere

Simulating Irregular Source Geometries for Ionian Plumes

Simulating Pluto's Atmosphere with Hybrid Fluid/Kinetic Models

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A comprehensive numerical simulation of Io’s sublimation-driven atmosphere

Cited by 56 publications

References 63 publications

Simulation of Plasma Interaction with Io’s Atmosphere

Simulation of Plasma Interaction with Io’s Atmosphere

Simulating Irregular Source Geometries for Ionian Plumes

Simulating Pluto&#39;s Atmosphere with Hybrid Fluid/Kinetic Models

Contact Info

Product

Resources

About

Simulating Pluto's Atmosphere with Hybrid Fluid/Kinetic Models