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Plasmaspheric Plumes Cause 'Detached' Proton Aurora

Proton Aurora

IMAGE-FUV imaging of the proton aurora, combined with EUV imaging of the plasmasphere, has shown that the detached afternoon-sector proton auroras discovered earlier by IMAGE have a source region in plasmaspheric plumes [Spasojevic et al., 2004]. Further work using correlative data from the Polar satellite's magnetometer has identified ion cyclotron waves in the plasmaspheric plumes, suggesting that pitch-angle scattering of energetic protons is the source mechanism for the detached arcs. This result verifies long-standing theoretical predictions about wave-particle interactions.

(2003: Sandel et al)

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Additional Information

Plasmasphere - An extension of Earth's upper atmosphere and ionosphere into space. This material is a charged plasma with particle energies below 100 electron Volts. The plasma is anchored to Earth's magnetic field and is dragged into a 24-hour 'co-rotational' orbit out to 10,000 kilometers or more.

Cyclotron Waves -When low-energy charged particles (electrons, ions) move in a magnetic field they move with a periodic 'orbital' period called the cyclotron frequency. When a plasma of ions move in a magnetic field, a wave-like resonance condition occurs at the cyclotron frequency which causes magneto-electric disturbances to travel through the plasma.

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Dr. S. Odenwald,, +1-301-286-6953
NSSDC, Mail Code 630, NASA Goddard Space Flight Center, Greenbelt, MD 20771
NASA Approval: J. L. Green,
Rev. 1.0.0, 24 July 2004, EVB II