Shocklets, SLAMS, and field‐aligned ion beams in the terrestrial foreshock. Issue 3 (6th March 2013)

• Record Type: Journal Article
• Authors: Wilson, L. B.; Koval, A.; Sibeck, D. G.; Szabo, A.; Cattell, C. A.; Kasper, J. C.; Maruca, B. A.; Pulupa, M.; Salem, C. S.; Wilber, M.
• Is Part Of: Journal of geophysical research. Volume 118:Issue 3(2013:Mar.)
• Page Start: 957
• Page End: 966
• Publication Date: 2013-03-06
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2012JA018186
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="jgra50051-para-0001">[1] We present Wind spacecraft observations of ion distributions showing field‐aligned beams (FABs) and large‐amplitude magnetic fluctuations composed of a series of shocklets and short large‐amplitude magnetic structures (SLAMS). The FABs are found to have <italic>T</italic><sub><italic>b</italic></sub> ~ 80 − 850 eV, <italic>V</italic><sub><italic>b</italic></sub>/<italic>V</italic><sub><italic>sw</italic></sub> ~ 1. 3 − 2. 4, <italic>T</italic><sub>⊥, <italic>b</italic></sub>/<italic>T</italic><sub>∥, <italic>b</italic></sub> ~ 1–8, and <italic>n</italic><sub><italic>b</italic></sub>/<italic>n</italic><sub><italic>o</italic></sub> ~ 0.2–11%. Saturation amplitudes for ion/ion resonant and non‐resonant instabilities are too small to explain the observed SLAMS amplitudes. We show two examples where groups of SLAMS can act like a local quasi‐perpendicular shock reflecting ions to produce the FABs, a scenario distinct from the more common production at the quasi‐perpendicular bow shock. The SLAMS exhibit a foot‐like magnetic enhancement with a leading magnetosonic whistler train, consistent with previous observations. Strong ion and electron heating are observed within the series of shocklets and SLAMS with temperatures increasing by factors ≳ 5 and ≳ 3, respectively. Both the core and halo electron components show strong perpendicular heating inside the feature.</p> </abstract>