Here are regions where different kinds of waves are thought to persist Powerful radio and plasma waves are central to the acceleration and loss of radiation belt particles Here are regions where different kinds of waves are thought to persist The Van Allen Probes provide the first simultaneous multipoint measurements of these waves over broad regions

Focus on chorus waves that we see on the Van Allen Probes Powerful radio and plasma waves are central to the acceleration and loss of radiation belt particles Focus on chorus waves that we see on the Van Allen Probes Particles can “surf” on waves and gain or loose tremendous amounts of energy The Van Allen Probes provide the first simultaneous multipoint measurements of these waves over broad regions

Resonant Wave Acceleration

Some of these waves are striking and beautiful to both the eye --- Power level triggered waveform capture – 16 bit data – very clear!! Chorus Waves

--- and to the ear Chorus Waves Power level triggered waveform capture – 16 bit data – very clear!! Chorus Waves

Now, unique 2-spacecraft measurements reveal many-hour persistence of Intense Low Frequency Electric Fields > 5-hours Van Allen Probe-A Van Allen Probe-B 00 04 08 12 16 20 00 October 13, 2012 Universal Time Waves at the edge of the radiation belts can last at least 5 hours during geomagnetic storms. This may be central to explaining how multi-MeV electrons are energized in the course of less than a day.

Van Allen Probes high-cadence sampling reveals strong correlation between chorus waves and magnetic storms Magnetic Storms DST Magnetic Storm Parameter This correlation may be central to the association of strong particle acceleration with some magnetic storms. But, why not all magnetic storms?

Summary The electric field and magnetic field measurements on the Van Allen Probes are the best ever made in the radiation belts. Two spacecraft is letting us see how long important waves persist – we’ve couldn’t do this before Magnetospheric activity clearly is correlated with key wave features such as chorus. These findings may be central to when, where, and how radiation belt particles are accelerated. This is just the beginning!!