This paper incorporates the Whistler waves theory previously embraced, said Shri Kanekal, the deputy mission scientist for the Van Allen Probes at NASAs Goddard Space Flight Center in Greenbelt, Maryland. But it provides a new explanation for how the particles get their initial push of energy. This first mechanism is based on something called time domain structures, which Mozer and his colleagues have identified previously in the belts. They are very short duration pulses of electric field that run parallel to the magnetic fields that thread through the radiation belts. These magnetic field lines guide the movement of all the charged particles in the belts: The particles move along and gyrate around the lines as if they were tracing out the shape of a spring. During this early phase, the electric pulses push the particles faster forward in the direction parallel to the magnetic fields. This mechanism can increase the energies somewhat – though not as high as traditionally thought to be needed for the Whistler waves to have any effect. However, Mozer and his team showed, through both data from the Van Allen Probes and from simulations, that Whistlers can indeed affect particles at these lower energies. Together the one-two punch is a mechanism that can effectively accelerate particles up to the intense speeds, which have for so long mysteriously appeared in the Van Allen belts. The Van Allen Probes have been able to monitor this acceleration process better than any other spacecraft because it was designed and placed in a special orbit for that purpose, said Mozer. The mission has provided the first really strong confirmation of whats happening. This is the first time we can truly explain how the electrons are accelerated up to nearly the speed of light. nasa.gov/content/goddard/van-allen-probes-shows-how-to-accelerate-electrons/#.VHYeBEvXlSU.
Posted on: Wed, 26 Nov 2014 19:26:02 +0000