Energization of planetary pickup ions in the solar system

Järvinen, R.; Kallio, Esa

doi:10.1002/2013je004534

Cited by 22 publications

(23 citation statements)

References 47 publications

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“…Let us consider the pickup ion (PUI) dynamics in the single‐particle picture in homogeneous electric and magnetic fields (e.g., Jarvinen & Kallio, ) corresponding to upstream conditions of Run 2 (see numerical values of the parameters in Table ). An O + ion picked up from rest (

O_{PUI}^{+}

) by the undisturbed solar wind has a gyroradius and period of

r_{L} (O_{PUI}^{+}) = m_{O^{+}} V_{E \times B} / (eB) = 5, 720

km and

τ_{L} (O_{PUI}^{+}) = 2 π m_{O^{+}} / (eB) = 155

s, where

m_{O^{+}}

is the oxygen mass and the drift velocity reads

V_{E \times B} = \overset{E}{true} \times \overset{B}{true} / B^{2}

and

\overset{E}{true} = - \overset{V}{true} \times \overset{B}{true}

.…”

Section: Discussionmentioning

confidence: 99%

“…Let us consider the pickup ion (PUI) dynamics in the single-particle picture in homogeneous electric and magnetic fields (e.g., Jarvinen & Kallio, 2014) corresponding to upstream conditions of Run 2 (see numerical values of the parameters in Table 1). is the length of one full gyrocycloid.…”

Section: Discussionmentioning

confidence: 99%

“…The distance heavy ions reach along the electric field is determined by their Larmor radii and, thus, by the magnitude of the interplanetary magnetic field (IMF) (Curry, Luhmann, Ma, Dong, et al, ; Jarvinen et al, ). The longer the distance, the higher the bulk energy over a Larmor period (Jarvinen & Kallio, ). Further, the heavy ion plume merges continuously to the tailward escape channels when moving from the Mars magnetosheath toward the wake (Dong et al, ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Oxygen Ion Energization at Mars: Comparison of MAVEN and Mars Express Observations to Global Hybrid Simulation

et al. 2018

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We study oxygen ion energization in the Mars‐solar wind interaction by comparing particle and magnetic field observations on the Mars Atmosphere and Volatile EvolutioN (MAVEN) and Mars Express missions to a global hybrid simulation. We find that large‐scale structures of the Martian‐induced magnetosphere and plasma environment as well as the Mars heavy ion plume as seen by multispacecraft observations are reproduced by the model. Using the simulation, we estimate the dynamics of escaping oxygen ions by analyzing their distance and time of flight as a function of the gained kinetic energy along spacecraft trajectories. In the upstream region the heavy ion energization resembles single‐particle solar wind ion pickup acceleration as expected, while within the induced magnetosphere the energization displays other features including the heavy ion plume from the ionosphere. Oxygen ions take up to 80 s and travel the distance of 20,000 km after their emission from the ionosphere to the induced magnetosphere or photoionization from the neutral exosphere before they have reached energies of 10 keV in the plume along the analyzed spacecraft orbits. Lower oxygen ion energies of 100 eV are reached faster in 10–20 s over the distance of 100–200 km in the plume. Our finding suggests that oxygen ions are typically observed within the first half of their gyrophase if the spacecraft periapsis is on the hemisphere where the solar wind convection electric field points away from Mars.

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O_{PUI}^{+}

) by the undisturbed solar wind has a gyroradius and period of

r_{L} (O_{PUI}^{+}) = m_{O^{+}} V_{E \times B} / (eB) = 5, 720

km and

τ_{L} (O_{PUI}^{+}) = 2 π m_{O^{+}} / (eB) = 155

s, where

m_{O^{+}}

is the oxygen mass and the drift velocity reads

V_{E \times B} = \overset{E}{true} \times \overset{B}{true} / B^{2}

and

\overset{E}{true} = - \overset{V}{true} \times \overset{B}{true}

.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxygen Ion Energization at Mars: Comparison of MAVEN and Mars Express Observations to Global Hybrid Simulation

et al. 2018

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“…Once produced, hot O collides with background neutral species, changing direction and losing energy. Several hot O transport models have been constructed to simulate this, including two-stream, Monte Carlo, and DSMC (Direct Simulation Monte Carlo) models [e.g., Nagy and Cravens, 1988;Ip, 1990;Kim et al, 1998;Hodges, 2000;Hać, 2009, 2014;Valeille et al, 2009aValeille et al, , 2009bValeille et al, , 2010aValeille et al, , 2010bYagi et al, 2012;Lee et al, 2013;Gröller et al, 2014]. But these photochemical escape rate calculations vary by about 2 orders of magnitude as summarized in Table 3 of Fox and Hać [2009], and there is a lack of direct observational constraint on photochemical escape models.…”

Section: Introductionmentioning

confidence: 99%

Pickup ion measurements by MAVEN: A diagnostic of photochemical oxygen escape from Mars

Rahmati

Cravens

Nagy

et al. 2014

Geophysical Research Letters

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A key process populating the oxygen exosphere at Mars is the dissociative recombination of ionospheric O 2 + , which produces fast oxygen atoms, some of which have speeds exceeding the escape speed and thus contribute to atmospheric loss. Theoretical studies of this escape process have been carried out and predictions made of the loss rate; however, directly measuring the escaping neutral oxygen is difficult but essential. This paper describes how energetic pickup ion measurements to be made near Mars by the SEP (Solar Energetic Particle) instrument on board the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft can be used to constrain models of photochemical oxygen escape. In certain solar wind conditions, neutral oxygen atoms in the distant Martian exosphere that are ionized and picked up by the solar wind can reach energies high enough to be detected near Mars by SEP.

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“…It is based on a hybrid-kinetic platform developed over the last fifteen years by our team to study the solar wind action on the plasma environment of various solar system bodies (Kallio & Janhunen 2002, 2003Kallio et al 2006a;Kallio & Jarvinen 2012;Jarvinen & Kallio 2014;Dyadechkin et al 2015, and references therein). Models at Mars and Venus (Kallio et al 2006bJarvinen et al 2009) or Titan (Sillanpää et al 2007) have given new insights regarding in-situ observations.…”

Section: A New Global 3d Hybrid Modelmentioning

confidence: 99%

Hybrid modelling of cometary plasma environments

Wedlund

Alho

Gronoff

et al. 2017

A&A

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Context. The ESA/Rosetta mission made it possible to monitor the plasma environment of a comet, from near aphelion to perihelion conditions. To understand the complex dynamics and plasma structures found at the comet, a modelling effort must be carried out in parallel. Aims. Firstly, we present a 3D hybrid model of the cometary plasma environment including photoionisation, solar wind charge exchange, and electron ionisation reactions; this model is used in stationary and dynamic conditions (mimicking the solar wind variations), and is thus especially adapted to a weakly outgassing comet such as 67P/Churyumov-Gerasimenko, the target of the ESA/Rosetta mission. Secondly, we use the model to study the respective effects of ionisation processes on the formation of the dayside macroscopic magnetic and density boundaries upstream of comet 67P in perihelion conditions at 1.3 AU. Thirdly, we explore and discuss the effects of these processes on the magnetic field line draping, ionisation rates, and composition in the context of the Rosetta mission. Methods. We used a new quasi-neutral hybrid model, originally designed for weakly magnetised planetary bodies, such as Venus, Mars, and Titan, and adapted here to comets. Ionisation processes were monitored individually and together following a probabilistic interaction scheme. Three-dimensional paraboloid fits of the bow shock surface, identified for a magnetosonic Mach number equal to 2, and of the cometopause surface, were performed for a more quantitative analysis. Results. We show that charge exchange and electron ionisation play a major role in the formation of a bow shock-like structure far upstream, while photoionisation is the main driver at and below the cometopause boundary, within 1000 km cometocentric distance. Charge exchange contributes to 42% of the total production rate in the simulation box, whereas production rates from electron ionisation and photoionisation reach 33% and 25%, respectively. We also discuss implications for Rosetta's observations, regarding the detection of the bow shock and the cometopause.

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Energization of planetary pickup ions in the solar system

Cited by 22 publications

References 47 publications

Oxygen Ion Energization at Mars: Comparison of MAVEN and Mars Express Observations to Global Hybrid Simulation

Oxygen Ion Energization at Mars: Comparison of MAVEN and Mars Express Observations to Global Hybrid Simulation

Pickup ion measurements by MAVEN: A diagnostic of photochemical oxygen escape from Mars

Hybrid modelling of cometary plasma environments

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