reinisch_ Solar Terrestrial Relations (Cravens, Physics of Solar Systems Plasmas, Cambridge U.P.) Lecture 1- Space Environment –Matter in Universe: 99.9% plasma –Plasma everywhere Solar Atmosphere Interplanetary Medium Planetary Magnetospheres Planetary Ionospheres

reinisch_ Space Environment Plasma = + and – charged particles (ions, electrons) and neutral particles Forces on charges particles –Electric force F E = qE –Magnetic force F B = qv x B –Lorentz force F = qE + qv x B –Neutral forcesmg,

reinisch_ Space Environment cont’d Solar wind Interplanetary magnetic field (IMF) –Tsyganenko model Magnetosphere –Dipole field??

reinisch_ Interplanetary Space and Magnetosphere Solar Wind. The SW is a collisionless supersonic (V SW > V S ) plasma that carries its own (solar) magnetic field with it. The Earth’s magnetic field presents a “hard” obstacle to the SW. The SW drapes around this obstacle forming a magnetic cavity that is shaped like a comet head and tail. Bow Shock. The bow shock is formed at x  12 R E sunward where p SW = p B. The SW decelerates at the bow shock becoming subsonic, but further downwind becomes supersonic again. Magnetosheath (note: Dr. Song is one of the world’s experts). Downwind from bow shock, the magnetosheath contains decelerated SW plasma. Some of this plasma fuses into the magnetosphere further along the tail. Magnetopause. Encloses the magnetosphere “shielding” it from the SW. Geocentric distance ~10 R E. Large current systems on the front (head) and the tail. Ne  50 cm -3. Magnetosphere. –Cusp, Plasmasphere, Ionosphere.

reinisch_ Earth’s Magnetosphere 1. Magnetosphere. Volume inside magnetopause. Geomagnetic forces dominate the motion of charged particles. Plasma originates from SW and the Earth’s ionosphere. SW enters in the polar cusp and along the tail. 2.Cusp (Cleft). SW entry point on the dayside. At ionospheric heights (300 km) it occupies a narrow latitudinal band near noon. 3.Plasma Sheet. Low density plasma originating in SW and ionosphere. But particles have much higher energy. Plasma flows into Earth’s atmosphere and forms the auroral ovals (borealis and australis). 4.Neutral Current Sheet. It is the separation between the earthward B-lines above (north) and the fieldline pointing away from the Earth below (south). Adawn-to-dusk current flows along the neutral current sheet, thus maintaining the oppositely directed magnetic fields (required/explained by Maxwell’s equations). At the “end” of the geomagnetic tail, the B-lines connect to the solar inter planetary magnetic field (IMF). This magnetic “reconnections” creates a voltage drop of ~100 kV creating currents of > 10 million amps. The potential drop projects down ionospheric heights creating a 100 kV voltage drop across the polar cap defining the dawn to dusk polar cap electric field.

reinisch_ Earth’s Magnetosphere cont’d 1.Van Allen Radiation Belts. Energetic particles near the plasma sheet center flowing earthward get trapped in closed magnetic field lines forming the radiation belts. The trapped particles spiral along the closed magnetic field lines, bouncing back and forth between the northern and southern hemisphere. Electrons and protons (and some O ions from the ionosphere) in the frequency range keV also have an azimuthal drift: electrons eastward, ions westward. This forms a current, the ring current. 2.Plasmasphere. A relatively high density plasma region closer to Earth, 100 cm -3. Decrease in density at the “Carpenter knee”, I.e., the plasmapause (F. 2.12). The plasmasphere rotates with the Earth. 3.Ionosphere. Earth’s atmosphere ionized by solar UV

SwRI NASA

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9

10 IMAGE Spacecraft

reinisch_ March 2000 Vandenburg AFB Delta II Rocket

reinisch_ Empirical Magnetospheric Density Distribution Average L = June LT March LT

reinisch_ Planets The Sun’s Planets The Planets’ Magnetospheres Mercury Venus (negligible, bow shock forms at ionopause) Earth Mars (very weak) Jupiter Saturn Uranus Neptune

reinisch_ Plasma and Neutral Parameters N e – electron density T e,i,n –electron/ion/neutral temperature N n – neutral density D – Debye length N D – number of particles in Debye sphere  p – 2  x plasma frequency  c – 2  x cyclotron (gyro) frequency r - gyroradius

reinisch_ Ch 2 - Kinetic Theory

reinisch_ Particle Distribution Function

reinisch_ Density Function n s

reinisch_ The Boltzmann Equation

reinisch_ Total Derivative in Phase Space

reinisch_ Examples of Distribution Functions