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Space Plasma Physics. Earth’s Radiation Belt. Xi Shao Department of Astronomy, University Of Maryland, College Park, MD 20742. Space Plasma Physics. Outline. History and importance of studying Earth’s radiation belt Dynamics of Earth’s radiation belt: Observations
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Space Plasma Physics Earth’s Radiation Belt Xi Shao Department of Astronomy, University Of Maryland, College Park, MD 20742
Space Plasma Physics Outline • History and importance of studying Earth’s radiation belt • Dynamics of Earth’s radiation belt: Observations • Origin of Earth’s radiation belt: Geomagnetic Storms and Substorms. • Modeling formation of Earth’s radiation belt. • Slot Region formation.
Radiation Belts: The Big Picture Explorer I Space Plasma Physics • The Radiation Belt is a energetic torus of energetic charged particles (plasma) around Earth, held in place by Earth's magnetic field • Historic discovery in 1958 by the Explorer I in 1958, and Explorer III missions, under Dr.James Van Allen at the University of Iowa. • The trapped radiation was first mapped out by Sputnik 3, Explorer IV, Pioneer III and Luna 1. • Energetic electrons form two distinct radiation belts, while protons form a single belt.
The Radiation Belts Today: a Dynamic Space Weather Environment • Space Weather Applications: • Astronauts safety • Hardware integrity • Mission performance • Satellite solar cell panel degradation • Single Event Upset (SEU)
The Radiation Belts Today: a Dynamic Space Weather Environment
Why Trapped? Proton Orbit Electron Orbit
NOAA POES Observations-Dynamical View Orbit Altitude: ~ 800 km Inclination: ~ 98 degree Orbit Period: ~100 mins MEPED Detector Energy Channels used in this poster: Proton: >80 MeV (Omni-Detector) Electron: > 300 keV (Omni-Directional flux derived from 2 telescopes) NOAA POES Data obtained from http://poes.ngdc.noaa.gov
Electron (> 300 keV) Belt Dynamics (1979-1991) Outer Belt Weakens Mar. 1991 Mar. 1989 Feb. 1986 Jul. 1982 Apr. 1981 Inner belt Enhanced
Electron (> 300 keV) Belt Dynamics (1992-2004) Outer Belt Weakens Oct-Nov, 2003 Inner belt Re-Enhanced NOAA-15 changes telescope pointing direction and data is still in processing for L < 2.
Proton (> 80 MeV) Belt Dynamics (1979-1991) Mar. 1991 Mar. 1989 Feb. 1986
Proton (> 80 MeV) Belt Dynamics (1992-2004) Oct-Nov, 2003
Radiation Belt inside the Earth’s Magnetosphere: Its Origin. Earth’s Magnetosphere
Space Plasma Physics Modeling Solar Wind Interaction with Earth’s Magnetosphere MHD Equations Solved on a 3D Stretched Spherical Mesh
Space Plasma Physics Magnetospheric Storms/Substorms
Space Plasma Physics • Magnetospheric Substorm
Mid-Tail Reconnection t= 00:-07:-48 t= 00:47:20 t= 00:51:05 t= 00:56:06 t= 01:01:07 t= 01:06:08
Space Plasma Physics Ring Current Development 1:00 UT
Space Plasma Physics Physical Modeling of Radiation Belt 3D Electric-Magnetic field from LFM Global MHD Model of Earth’s Magnetosphere Initial Test Particle Distribution 3D Particle Tracing Code (Full Motion for Protons, and Guiding Center for electrons) e RB energetic particle distribution p
Energization of Radiation Belt Electrons Initial Configuration of 5keV electrons A snapshot of electron location and energy in 3D10 mins later
Formation of Slot Region in Electron Radiation Belt Whistler Waves in the Plasmasphere Slot Region
Summary • Review History and Importance of Radiation Belt • Radiation Belt Structure • Origin of Radiation Belt • Radiation Belt Slot region • Safe-zone Solar-Cycle Shifting.
Outstanding science questions • Acceleration mechanisms; • their relative significance • Solar wind-inner magnetosphere coupling • Loss mechanisms • User needs a Model: • Accurate flux models • L shell specificity • Forensic evaluation • Nowcasting