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Published byVirginia Norris Modified over 9 years ago
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First Direct Experimental Measurement of loss cone scattering of energetic electrons by whistler mode hiss in the plasmasphere Van Allen Probes/BARREL 2014 cooperative campaign. EFW team: Aaron Breneman, John Wygant, John Bonnell, Scott Thaller, Kris Kersten and others University of Minnesota BARREL team: Robyn Millan, Alexa Halford, Leslie Woodger, John Sample and others Dartmouth EMFISIS team: Craig Kletzing, Scott Bounds, George Hospodarsky, Bill Kurth and others MagEIS team: Joe Fennell
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Quick Results First direct experimental verification that hiss causes e- loss in plasmasphere Surprise result: – Correlations occur over LARGE regions and therefore have global effect on radiation belts. ~2 min period fluctuations
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Quasi-linear diffusion calculation Angular random walk distance in bounce period 50–100 keV e- will scatter ∼ 1◦ over 1 sec bounce period when interacting with the observed hiss. MagEIS flux at 8 deg PA channel has 90,000 e- /s/cm3/keV/sr at 50 keV. Scaling this to BARREL field-of-view mapped to mag eq for single bounce period we find 8x10^20 e-/s scattered into DLC Balloon 2I observes roughly 1,000,000 e−/cm2/s for the 50-100 keV range. Scaling to field-of-view (circle of 100 km radius at 70 km) we find 3x 10^20 e−/s. Theoretical precipitation flux closely matches observed flux!
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Extended mission opportunity …or the Van Allen Probe/BARREL/MMS science triumvirate Is the source of global-scale coherence in ULF period fluctuations of hiss and x- rays generated external or internal to magnetosphere? Compare observations of: – BARREL x-rays from 2015 N hemisphere campaign – Van Allen Probe hiss, density, Bo – MMS ULF period fluctuations in solar wind
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# Conjunctions/(Hr_MLT * L) MLT L L L LLL BARREL Extended Mission Kiruna, Sweden 5 Payloads Turn-Around (August) 2015 Balloons mostly Geostationary Consider RBSP Extended Mission Nominal Orbit (No Change) Predicted 1Payload BARREL & RBSP Conjunctions August 2015 Kiruna, Sweden RBSP A FootPt RBSP B FootPt August 2015 Kiruna, Sweden RBSP A FootPt RBSP B FootPt Conjunctions for 2 Week Mission (Aug. 10-24, 2015) Conjunction – Any time a RBSP satellite is in same 1Hr by 1 L-value bin with a single BARREL balloon per hour UT time Conjunctions on Dayside Dusk sector mostly occur near Apogee Separation of Payloads at Apogee could increase conjunction duration
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Larger separation at apogee could provided extended time period of conjunctions with satellites on either side of payload 2015/08/18 12:00 VAPA VAPB 2015/08/18 12:00 VAPA VAPB 2015/08/18 12:00 VAPA VAPB 2015/08/18 12:00 VAPA VAPB Nominal Orbit (No Change)Increase Delta Apogee by 200% Increase Delta Apogee by 300% Increase Delta Apogee by 200%, Decrease VAP A Perigee by 25 km
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