UMBC Goddard Planetary Heliophysics Institute (GPHI)

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In May 2011, the NASA Goddard Space Flight Center (GSFC) awarded a Cooperative Agreement to the University of Maryland, Baltimore County, to create a science center for collaborative research in Solar-Planetary Sciences at NASA’s Goddard Space Flight Center, Greenbelt, MD. Through this arrangement, UMBC and its partners – University of Maryland College Park and American University – developed collaborative research programs in all areas of the Heliophysics sciences. This consortium between government and universities to create GPHI (Goddard Planetary Heliophysics Institute) not only provided a secure “home” for Heliophysics scientists, but also synergistically fostered new directions in research and technology.

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    Orbital control strategy for a CubeSat satellite equipped with a solar sail for Earth-Mars communications during solar conjunctions
    (2024-01-27) Centeno, Leonor Cui Domingo; Farrés, Ariadna
    This paper presents a mission concept that enables Earth-Mars communications resistant to periods of solar conjunction by using CubeSat satellites equipped with a solar sail. The dynamics of the satellite is modeled separately in the respective Earth-Sun and Mars-Sun Restricted Three Body Problem (RTBP), modified to include the solar radiation pressure effect exerted on the sail. Due to the non-linearities presented on this model, we numerically determine the location of the non-eclipsed equilibrium points parameterized by the sail orientation through a continuation method. These are the points where two CubeSat nanosatellites equipped with a solar sail could be placed. The instability of these equilibrium points makes it necessary to implement a control strategy to keep the satellite's trajectory close to equilibrium by constantly changing the orientation of the sail. To prove the robustness of the strategy, some numerical simulations have been performed for a given period of mission.
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    Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity
    (AAS, 2024-01-17) Krupar, Vratislav; Kruparova, Oksana; Szabo, Adam; Nemec, Frantisek; Maksimovic, Milan; Martinez Oliveros, Juan Carlos; Lario, David; Bonnin, Xavier; Vecchio, Antonio; Pulupa, Marc; Bale, Stuart D.
    We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available multispacecraft data. The first method utilizes intensity fitting with a circular Gaussian distribution, while the second method is based on the time arrival of radio bursts. We demonstrate the effectiveness of these methods through the analysis of a single type III burst event and compare their results with the traditional radio triangulation technique. Furthermore, we conduct a statistical study of 17 type III bursts associated with M- and X-class solar flares in years 2020–2022. Our findings suggest a possible correlation between solar flare intensities and longitudes, with east limb flares tending to be weaker than west limb flares. We also observe a systematic drift of radio burst longitudes toward the east, potentially explained by a poleward component of the local density gradient. Our results suggest a strong correlation between solar flare intensities and radio burst properties, enhancing our understanding of the relationship between solar flares and type III radio bursts.
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    Pickup Ion Injection and Acceleration at Perpendicular Shocks
    (AIP, 1999-08-25) Zank, G. P.; Lipatov, Alexander
    Results from a multiscale hybrid kinetic simulation of low plasma beta supercritical perpendicular shocks are presented. Freshly ionized pickup ions are included self-consistently. It is found that perpendicular shocks can accelerate pickup ions from an initial thermal" shell distribution to high energies. The mechanism by which the pickup ions are energized is that of multiply reflected ion (MRI) acceleration Zank et al., 1996; Lee et al., 1996 . The injection efficiency is found to be very high and maximum energies of nearly 0.5 MeV are attained. MRI acceleration may provide a solution to the so-called injection problem for anomalous cosmic rays.
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    NUMERICAL SIMULATION OF THE EFFECTS OF MAGNETIC FIELD INDUCED BY PLASMA FLOW PAST NONMAGNETIC PLANETS
    (NASA) Lipatov, Alexander
    The interaction of a nonstationary plasma flow with a model ionosphere is studied. On the basis of a numerical simulation, the calculation yields results of the distribution of the plasma concentration and magnetic field in the transition region.
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    Numerical simulation of shock waves near comets: structural features and energy dissipation mechanisms
    (AIP, 1985-06-18) Galeev, A. A.; Lipatov, Alexander; Sagdeev, R. Z.
    The structure of a shock wave near a comet is investigated by means of numerical simulation. It is shown that the main contribution to energy dissipation at the wave front is made by ions from the comet produced in the solar wind due to the ionization of the neutral atmosphere of the comet. Due to the high cyclotron gyration velocity, some of them go out ahead of the wave front and are further accelerated in the electric field of the solar wind. However, this dissipation is insufficient and a resistive jump with a much smaller scale is established inside the shock front on a scale comparable to the Larmor radius of a cometary ion.
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    Hybrid simulations of whistler waves generation and current closure by a pulsed tether in the ionosphere
    (AGU, 1994-06-01) Chang, C. L.; Lipatov, Alexander; Drobot, A. T.; Papadopoulos, K.; Satya-Narayana, P.
    The dynamic response of a magnetized collisionless plasma to an externally driven, finite size, sudden switch-on current source across the magnetic field has been studied using a two dimensional hybrid code. It was found that the predominant plasma response was the excitation of whistler waves and the formation of current closure by induced currents in the plasma. The results show that the current closure path consists of: a) two antiparallel field-aligned current channels at the end of the imposed current sheet; and b) a cross-field current region connecting these channels. The formation of the current closure path occured in the whistler timescale much shorter than that of MHD and the closure region expanded continuously in time. The current closure process was accompanied by significant energy loss due to whistler radiation.
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    Hybrid simulation of comet Shoemaker-Levy 9 interaction with Jovian bow shock
    (AGU, 1994-06-01) Lipatov, Alexander; Sharma, A. S.
    The interaction of the solar wind with comet Shoemaker-Levy 9 leading to the formation of the cometary magnetosphere and its interaction with the Jovian bow shock is simulated using a one dimensional hybrid code. The mass loading of the solar wind by the cometary ions leads to the formation of a bow shock behind which the plasma density is 2–3 cm⁻³ and the electron temperature is 4 eV. The interaction of this system with the Jovian bow shock yields local enhancements of the magnetic field and the plasma density by factors of 4-5 and the electron temperature by 2-3.
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    The interaction of neutral interstellar H with the heliosphere: A 2.5-D particle-mesh boltzmann simulation
    (AGU, 1998-09-01) Lipatov, Alexander; Zank, G. P.; Pauls, H. L.
    A nonstationary Boltzmann particle-mesh method for neutral hydrogen originating from either the interstellar medium, the heliosheath, or the solar wind has been developed to simulate the detailed interaction of the solar wind with the local interstellar medium (LISM). Such a Boltzmann description for the hydrogen serves to capture the complicated neutral distribution. The neutral component is coupled to a hydrodynamic plasma through charge exchange. The distribution of the ionized component was taken from a two-shock model [Zank et al., 1996b]. This approach is used (1) to elucidate the nature of the solar wind - LISM interaction more carefully than has been done previously in a multifluid approach [Zank et al., 1996b] and (2) to identify precisely the role played by the three identifiably distinct neutral populations in determining the global structure and dynamics of the heliosphere. The differences in the global neutral H distribution that exist between Boltzmann and multifluid gasdynamic models axe discussed briefly.
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    The acceleration of pickup ions at shock waves: Test particle-mesh simulations
    (AGU, 1998-12-01) Lipatov, Alexander; Zank, G. P.; Pauls, H. L.
    A mechanism for the acceleration of pickup ions by repeated reflection from the electrostatic cross-shock potential of a quasi-perpendicular shock was proposed independently by Zank et al. [1996b] and Lee et al. [1996]. The acceleration mechanism, known variously as Multiply Reflected Ion (MRI) acceleration or “shock surfing,” was studied by these authors in the limit of an idealized shock, which possessed neither fine-scale structure (distinct foot, ramp, or overshoot) nor pickup ion scattering turbulence. Here the acceleration of pickup ions at cometary and interplanetary shocks and at the termination shock is studied in the “test” particle limit on the basis of a particle-mesh simulation. All simulations assume a shell distribution for the pickup ions (either pickup protons or helium), and the dynamics of pickup ions propagating in a fixed electromagnetic field profile are investigated. The effect of a shock foot, ramp and overshoot on the acceleration of pickup ions at perpendicular and oblique shocks is described. The acceleration of pickup ions in the presence of strong turbulence inside the foreshock region is also addressed. For quasi-perpendicular shocks with structure, we obtained the following results. First, the accelerated H⁺ and He⁺ spectrum is a very hard power law ∝ E⁻ᵏ, k = 0.92–1.2, which is much harder than that predicted by diffusive shock acceleration. Also, as θbₙ, the angle between the upstream magnetic field and shock normal, decreases from 90°, the accelerated pickup ion spectrum flattens until MRI acceleration ceases. Second, the fine structure of the shock is found to reduce slightly the maximum energy gain for an accelerated pickup ion compared to that gained at an unstructured shock. Third, a flat turbulence spectrum is found to lead to an increase in the maximum energy for transmitted pickup ions, whereas a power law turbulence spectrum leads to a modest reduction in the maximum pickup ion energy gain. However, the basic MRI acceleration mechanism continues to operate in the presence of turbulent magnetic fluctuations and the characteristic hard spectra are preserved. Fourth, MRI acceleration is found to work only for those shocks for which θbₙ>60°–70°. The results from the test particle simulations described here are also used to interpret particle acceleration in self-consistent hybrid simulations.
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    Pickup Ion Acceleration at Low- βₚ Perpendicular Shocks
    (APS, 1998-07-27) Lipatov, Alexander; Zank, G. P.
    Multiscale hybrid kinetic simulations of low- βₚ supercritical shocks demonstrate that pickup ions may be strongly accelerated by shock surfing, also known as multiply reflected ion acceleration.
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    Self-consistent hybrid simulations of the interaction of the heliosphere with the local interstellar medium
    (AGU, 2000-12-01) Müller, Hans-Reinhard; Zank, Gary P.; Lipatov, Alexander
    A new method for investigating the interaction of the solar wind with the partially ionized local interstellar medium (LISM) is presented. The solar wind and the interstellar plasma are modeled using a two-dimensional (2-D) hydrodynamic numerical code. The plasma is coupled to the neutral hydrogen (of both interstellar and solar wind origin) via resonant charge exchange. To model the neutral H distribution, we use a nonstationary 2.5-D particle mesh, method to solve the Boltzmann equation, which is coupled self-consistently to the interstellar and solar wind plasma. Numerical self-consistency is achieved by iterating the plasma and neutral H distributions between the two numerical schemes until a steady state is achieved. Results from three test applications are presented and discussed, including the first one-shock kinetic simulation. The simulations are able to reproduce the main features of the heliosphere such as shock structure, hydrogen wall, and heating, deceleration and filtration of neutral hydrogen. In addition, they enable the study and interpretation of the non-Maxwellian hydrogen distribution function. Traces of fast neutrals originating inside the termination shock and the heliosheath/heliotail region can be found far upstream of the outer heliosphere. The influence of different interstellar plasma boundary values on the heliosphere is highlighted in the comparison of two supersonic simulations and one subsonic simulation. In particular, by comparing the simulated energetic neutral atom (ENA) fluxes at 1 AU of the supersonic and subsonic models, it is found that the subsonic flux is significantly underabundant in the energy range 10 – 60 eV compared to the supersonic case. This may offer an important diagnostic for determining whether the heliosphere possesses a bow shock or not.
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    Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model
    (NASA, 2004-01-01) Lipatov, Alexander; Combi, Michael R.
    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 was a production of the structure of the double-peak in the magnetic field signature of the I0 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.
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    Saturn's magnetospheric interaction with Titan as defined by Cassini encounters T9 and T18: New results
    (Elsevier, 2009-10-24) Sittler Jr., E.C.; Hartle, R.E.; Johnson, R.E.; Cooper, J.F.; Lipatov, Alexander; Bertucci, C.; Coates, A.J.; Szego, K.; Shappirio, M.; Simpson, D.G.; Wahlund, J.-E.
    We present new results of Cassini's T9 flyby with complementary observations from T18. Based on Cassini plasma spectrometer (CAPS) and Cassini magnetometer (MAG), compositional evidence shows the upstream flow for both T9 and T18 appears composed of light ions (H⁺ and H₂⁺), with external pressures ∼30 times lower than that for the earlier TA flyby where heavy ions dominated the magnetospheric plasma. When describing the plasma heating and sputtering of Titan's atmosphere, T9 and T18 can be considered interactions of low magnetospheric energy input. On the other hand, T5, when heavy ion fluxes are observed to be higher than typical (i.e., TA), represents the limiting case of high magnetospheric energy input to Titan's upper atmosphere. Anisotropy estimates of the upstream flow are 1
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    The light (H⁺, H⁺₂, He⁺) and heavy (Na⁺) pickup ion dynamics in the lunar-like plasma environment: 3D hybrid kinetic modeling
    (Elsevier, 2013-08-29) Lipatov, Alexander; Cooper, J.F.; Sittler Jr., E.C.; Hartle, R.E.
    In this report we discuss the self-consistent dynamics of pickup ions in the solar wind flow around the lunar-like object. In our model the solar wind and pickup ions are considered as a particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. The Moon will be chosen as a basic object for our modeling. The current modeling shows that mass loading by pickup ions H⁺, H⁺₂, He⁺ and Na⁺ may be very important in the global dynamics of the solar wind around the Moon. In our hybrid modeling we use exponential profiles for the exospheric components. The Moon is considered as a weakly conducting body. Special attention will be paid to comparing the modeling pickup ion velocity distribution with ARTEMIS observations. Our modeling shows an asymmetry of the Mach cone due to mass loading, the upstream flow density distribution and the magnetic field. The pickup ions form an asymmetrical plasma tails that may disturb the lunar plasma wake.
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    Titan׳s plasma environment: 3D hybrid kinetic modeling of the TA flyby and comparison with CAPS-ELS and RPWS LP observations
    (Elsevier, 2014-03-05) Lipatov, Alexander; Sittler Jr., E.C.; Hartle, R.E.; Cooper, J.F.; Simpson, D.G.
    In this report we discuss the global plasma environment of the TA flyby from the perspective of 3D hybrid modeling. In our model the background, pickup, and ionospheric ions are considered as particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. We also take into account the collisions between the ions and neutrals. Our modeling shows that mass loading of the background plasma (H⁺, O⁺) by pickup ions H⁺₂ , CH⁺₂, and N⁺₂ differs from the T9 encounter simulations when O⁺ ions are not introduced into the background plasma. In our hybrid modeling we use Chamberlain profiles for the atmospheric components. We also include a simple ionosphere model with average mass M=28 amu ions that were generated inside the ionosphere. Titan׳s interior is considered as a weakly conducting body. Special attention has been paid to comparing the simulated pickup ion density distribution with CAPS-ELS and with RPWS LP observations by the Cassini–Huygens spacecraft along the TA trajectory. Our modeling shows an asymmetry of the ion density distribution and the magnetic field, including the formation of Alfvén wing-like structures.
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    Short wavelength electromagnetic perturbations excited near the Solar Probe Plus spacecraft in the inner heliosphere: 2.5D hybrid modeling
    (Elsevier, 2011-12-14) Lipatov, Alexander; Sittler Jr., Edward C.; Hartle, Richard E.; Cooper, John F.
    A 2.5D numerical plasma model of the interaction of the solar wind (SW) with the Solar Probe Plus spacecraft (SPPSC) is presented. These results should be interpreted as a basic plasma model derived from the SW interaction with the spacecraft (SC), which could have consequences for both plasma wave and electron plasma measurements on board the SC in the inner heliosphere. Compression waves and electric field jumps with amplitudes of about 1.5 V/m and (12-18) V/m were also observed. A strong polarization electric field was also observed in the wing of the plasma wake. However, 2.5D hybrid modeling did not show excitation of whistler/Alfvén waves in the upstream connected with the bi-directional current closure that was observed in short-time 3D modeling SPPSC and near a tether in the ionosphere. The observed strong electromagnetic perturbations may be a crucial point in the electromagnetic measurements planned for the future Solar Probe Plus (SPP) mission. The results of modeling electromagnetic field perturbations in the SW due to “shot” noise in absence of SPPSC are also discussed.
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    Effects of Na⁺ and He⁺ pickup ions on the lunar-like plasma environment: 3D hybrid modeling
    (Elsevier, 2012-07-20) Lipatov, Alexander; Cooper, J.F.; Sittler Jr., E.C.; Hartle, R.E.
    In this report we discuss the self-consistent dynamics of pickup ions in the solar wind flow around the lunar-like object. In our model the solar wind and pickup ions are considered as a particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. The Moon will be chosen as a basic object for our modeling. The current modeling shows that mass loading by pickup ions Na⁺ and He⁺ may be very important in the global dynamics of the solar wind around the Moon. In our hybrid modeling we use exponential profiles for the exospheric components. The Moon is considered as a weakly conducting body. Special attention will be paid to comparing the modeling pickup ion velocity distribution with ARTEMIS observations. Our modeling shows an asymmetry of the Mach cone due to mass loading, the upstream flow density distribution and the magnetic field. The pickup ions form an asymmetrical plasma tails that may disturb the lunar plasma wake.
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    Global effects of transmitted shock wave propagation through the Earth's inner magnetosphere: First results from 3-D hybrid kinetic modeling
    (Elsevier, 2016-07-21) Lipatov, Alexander; Sibeck, D.G.
    We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmaspheric particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, wave–particle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that shocks cause strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us determine energy transport through the Earth's inner magnetosphere.