Relativistic Particle Beams as a Resource to Solve Outstanding Problems in Space Physics

Sánchez, E. R.; Powis, Andrew; Kaganovich, Igor; Marshall, R. A.; Porazik, P.; Greklek-McKeon, Michael; Amin, K.; Shaw, David T.; Nicolls, Micale

doi:10.3389/fspas.2019.00071

Cited by 14 publications

(13 citation statements)

References 134 publications

(161 reference statements)

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“…(2019), Sanchez et al. (2019) and Willard et al. (2019) incorrectly allude that the loss‐cone shift is a relativistic effect, whereas it is not.…”

Section: Discussionmentioning

confidence: 99%

“…Knowledge of the loss‐cone shift is particularly important for proposed experiments wherein high‐energy electron beams are fired from spacecraft in the magnetospheric equator into the loss cone to illuminate the upper atmosphere in the sense of artificial aurora (Borovsky, Delzanno, Dors, et al., 2020; Borovsky, Delzanno, & Henderson, 2020; Delzanno et al., 2016; Porazik et al., 2014; Powis et al., 2019; Sanchez et al., 2019; Willard et al., 2019). Knowledge of the loss‐cone shift is knowledge about where to aim the accelerator.…”

Section: Introductionmentioning

confidence: 99%

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Modification of the Loss Cone for Energetic Particles in the Earth's Inner Magnetosphere

2022

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The behavior of energetic particles in the Earth's dipole and stretched magnetic‐field models is explored with a focus on the shift of the atmospheric loss cone away from the magnetic‐field direction and on non‐adiabatic behavior occurring when the particle gyroradius becomes comparable with the gradient scale length of the local magnetic field. It is shown that the equatorial loss cone is aberrated away from the magnetic‐field direction (pitch angle of 0°) by the perpendicular drift of a charged particle (which is referred to as the “Mozer transform” described in Mozer (1966, https://doi.org/10.1029/JZ071i011p02701). It is found that the Mozer coordinate transformation in pitch‐angle/gyrophase‐angle space better organizes the behavior of bounce times, mirror altitudes, drift speeds, and first adiabatic invariant. It also describes the loss‐cone shift accurately for a certain range of values of the adiabaticity parameter ϵ, defined by the ratio of the particle gyroradius to the local radius of curvature of the magnetic field. For particles with larger ϵ, the Mozer transform (evaluated with the standard gradient‐curvature drift) breaks down and the “central trajectory” theory can be used to calculate the angular shift of the loss cone, which now includes an Earthward shift. When ϵ becomes relatively large, stochastic field line curvature (FLC) scattering occurs: we show the intimate connection between the strength of FLC scattering and the loss‐cone shift. By comparing ion orbits in the dipole and Tsyganenko (Ts89 and Ts04) magnetic fields, we conclude that the loss cone of ring‐current ions is significantly modified during geomagnetically active times.

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“…(2019), Sanchez et al. (2019) and Willard et al. (2019) incorrectly allude that the loss‐cone shift is a relativistic effect, whereas it is not.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modification of the Loss Cone for Energetic Particles in the Earth's Inner Magnetosphere

2022

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“…Finally, there is an extensive literature describing how energetic electron beams could be used to study mesospheric chemistry (Neubert et al, 1990;Marshall et al, 2019), atmospheric electricity (Banks et al, 1990;Neubert et al, 1990;Neubert and Gilchrist, 2004;Marshall et al, 2019;Sanchez et al, 2019;Borovsky et al, 2020c), atmospheric electron-attachment physics and electrical conductivity (Banks et al, 1990;Neubert et al, 1996;Neubert and Gilchrist, 2004;Borovsky, 2017), and plasmawave generation (Carlsten et al, 2018;Delzanno and Roytershteyn, 2019;Reeves et al, 2020).…”

Section: Other Sciencementioning

confidence: 99%

A Mission Concept to Determine the Magnetospheric Causes of Aurora

Borovsky

Delzanno

Henderson

2020

Front. Astron. Space Sci.

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Insufficiently accurate magnetic-field-line mapping between the aurora and the equatorial magnetosphere prevents us from determining the cause of many types of aurora. An important example is the longstanding question of how the magnetosphere drives low-latitude (growth-phase) auroral arcs: a large number of diverse generator mechanisms have been hypothesized but equatorial magnetospheric measurements cannot be unambiguously connected to arcs in the ionosphere, preventing the community from identifying the correct generator mechanisms. Here a mission concept is described to solve the magnetic-connection problem. From an equatorial instrumented spacecraft, a powerful energetic-electron beam is fired into the atmospheric loss cone resulting in an optical beam spot in the upper atmosphere that can be optically imaged from the ground, putting the magnetic connection of the equatorial spacecraft’s measurements into the context of the aurora. Multiple technical challenges that must be overcome for this mission concept are discussed: these include spacecraft charging, beam dynamics, beam stability, detection of the beam spot in the presence of aurora, and the safety of nearby spacecraft.

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“…Earlier Porazik et al (2014) explored the loss-cone shift in a more-complicated fashion using the Gardner-expansion (Gardner, 1966) for the first adiabatic invariant μ. (See also Sanchez et al (2019), Powis et al (2019), andWillard et al (2019) for discussions of the loss-cone shift in terms of the Gardner expansion.) Looking beyond the shift of the loss cone, in this paper an angular coordinate system will be explored that organizes the behavior of energetic ions and electrons bouncing in the Earth's dipole.…”

Section: Introductionmentioning

confidence: 99%

Pitch-Angle Diffusion in the Earth’s Magnetosphere Organized by the Mozer-Transformed Coordinate System

Borovsky

Delzanno

Yakymenko

2022

Front. Astron. Space Sci.

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In the Earth’s dipole magnetosphere finite-gyroradius effects produce a shift of the atmospheric loss cone away from the direction of the magnetic field. This loss-cone shift is theoretically described by the “Mozer transform” [Mozer, F. S. (1966). Proton trajectories in the radiation belt. J. Geophys. Res. 71:2701], which is based upon the curvature drift of particles crossing the equatorial plane. For positive ions the northern and southern loss cones both shift westward and for electrons the northern and southern loss cones both shift eastward. This loss-cone shift is part of a coordinate-system transform, with the transformed coordinates better organizing the behavior of particle orbits in the dipole magnetic field (e.g. first adiabatic invariants, mirror heights, and bounce times). In this report it is demonstrated that the transformed coordinate system also properly organizes pitch-angle diffusion. This improved organization of the diffusion is true whether the angular scattering is produced by plasma-wave scattering or by field-line-curvature (FLC) scattering. It is shown that FLC scattering and the loss cone shift are linked, so that if FLC scattering is occurring, there is a loss cone shifted away from the magnetic-field direction and the Mozer-transformed coordinates are needed.

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Relativistic Particle Beams as a Resource to Solve Outstanding Problems in Space Physics

Cited by 14 publications

References 134 publications

Modification of the Loss Cone for Energetic Particles in the Earth's Inner Magnetosphere

Modification of the Loss Cone for Energetic Particles in the Earth's Inner Magnetosphere

A Mission Concept to Determine the Magnetospheric Causes of Aurora

Pitch-Angle Diffusion in the Earth’s Magnetosphere Organized by the Mozer-Transformed Coordinate System

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