Helium in the Earth's foreshock : a global Vlasiator survey

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dc.contributor.author Battarbee, Markus
dc.contributor.author Blanco-Cano, Xochitl
dc.contributor.author Turc, Lucile
dc.contributor.author Kajdic, Primoz
dc.contributor.author Johlander, Andreas
dc.contributor.author Tarvus, Vertti
dc.contributor.author Fuselier, Stephen
dc.contributor.author Trattner, Karlheinz
dc.contributor.author Alho, Markku
dc.contributor.author Brito, Thiago
dc.contributor.author Ganse, Urs
dc.contributor.author Pfau-Kempf, Yann
dc.contributor.author Akhavan-Tafti, Mojtaba
dc.contributor.author Karlsson, Tomas
dc.contributor.author Raptis, Savvas
dc.contributor.author Dubart, Maxime
dc.contributor.author Grandin, Maxime
dc.contributor.author Suni, Jonas
dc.contributor.author Palmroth, Minna
dc.date.accessioned 2020-11-19T09:49:02Z
dc.date.available 2020-11-19T09:49:02Z
dc.date.issued 2020-10-20
dc.identifier.citation Battarbee , M , Blanco-Cano , X , Turc , L , Kajdic , P , Johlander , A , Tarvus , V , Fuselier , S , Trattner , K , Alho , M , Brito , T , Ganse , U , Pfau-Kempf , Y , Akhavan-Tafti , M , Karlsson , T , Raptis , S , Dubart , M , Grandin , M , Suni , J & Palmroth , M 2020 , ' Helium in the Earth's foreshock : a global Vlasiator survey ' , Annales Geophysicae , vol. 38 , no. 5 , pp. 1081-1099 . https://doi.org/10.5194/angeo-38-1081-2020
dc.identifier.other PURE: 151460812
dc.identifier.other PURE UUID: f7ae7243-505d-4be1-a421-b4e6e26d15ef
dc.identifier.other WOS: 000584320200001
dc.identifier.other ORCID: /0000-0001-7055-551X/work/83838955
dc.identifier.other ORCID: /0000-0003-4857-1227/work/83841652
dc.identifier.other ORCID: /0000-0002-6373-9756/work/83841872
dc.identifier.other ORCID: /0000-0002-7576-3251/work/83843141
dc.identifier.other ORCID: /0000-0002-3369-4761/work/83843245
dc.identifier.other ORCID: /0000-0001-5793-7070/work/83843280
dc.identifier.other ORCID: /0000-0002-2531-5848/work/83843342
dc.identifier.uri http://hdl.handle.net/10138/321699
dc.description.abstract The foreshock is a region of space upstream of the Earth's bow shock extending along the interplanetary magnetic field (IMF). It is permeated by shock-reflected ions and electrons, low-frequency waves, and various plasma transients. We investigate the extent of the He2+ foreshock using Vlasiator, a global hybrid-Vlasov simulation. We perform the first numerical global survey of the helium foreshock and interpret some historical foreshock observations in a global context. The foreshock edge is populated by both proton and helium field-aligned beams, with the proton foreshock extending slightly further into the solar wind than the helium foreshock and both extending well beyond the ultra-low frequency (ULF) wave foreshock. We compare our simulation results with Magnetosphere Multiscale (MMS) Hot Plasma Composition Analyzer (HPCA) measurements, showing how the gradient of suprathermal ion densities at the foreshock crossing can vary between events. Our analysis suggests that the IMF cone angle and the associated shock obliquity gradient can play a role in explaining this differing behaviour. We also investigate wave-ion interactions with wavelet analysis and show that the dynamics and heating of He2+ must result from proton-driven ULF waves. Enhancements in ion agyrotropy are found in relation to, for example, the ion foreshock boundary, the ULF foreshock boundary, and specular reflection of ions at the bow shock. We show that specular reflection can describe many of the foreshock ion velocity distribution function (VDF) enhancements. Wave-wave interactions deep in the foreshock cause de-coherence of wavefronts, allowing He2+ to be scattered less than protons. en
dc.format.extent 19
dc.language.iso eng
dc.relation.ispartof Annales Geophysicae
dc.rights cc_by
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject FIELD-ALIGNED BEAMS
dc.subject ALPHA-PARTICLES
dc.subject ION DISTRIBUTIONS
dc.subject BOW SHOCK
dc.subject ULF FORESHOCK
dc.subject UPSTREAM
dc.subject PROTONS
dc.subject WIND
dc.subject ACCELERATION
dc.subject PLASMA
dc.subject 115 Astronomy, Space science
dc.subject 114 Physical sciences
dc.title Helium in the Earth's foreshock : a global Vlasiator survey en
dc.type Article
dc.contributor.organization Space Physics Research Group
dc.contributor.organization Particle Physics and Astrophysics
dc.contributor.organization Department of Physics
dc.description.reviewstatus Peer reviewed
dc.relation.doi https://doi.org/10.5194/angeo-38-1081-2020
dc.relation.issn 0992-7689
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

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