The Earth as a Natural Particle Accelerator

Fri., Feb. 27, 2015 3:30 p.m. - Fri., Feb. 27, 2015 4:30 p.m.

Location: LB 235

Abstract:
Beyond the top of our atmosphere, we are surrounded at all times by a supersonic flow of material from the sun known as the solar wind. Earth's magnetic field largely deflects the solar wind around the planet, forming a buffer region of plasma-filled space: the magnetosphere. The magnetosphere absorbs energy during its interaction with the solar wind, and some of this energy goes into accelerating particles to MeV energies. These high-energy particles become trapped by the Earth's magnetic field for months, posing a hazard to spacecraft that must travel through belts of high-energy trapped particles. Moreover, the energetic particles occasionally dump into Earth's upper atmosphere, creating a radiation hazard down to airplane altitudes and altering the chemistry of the upper atmosphere.

I will discuss the physical mechanisms by which the Earth accelerates high-energy electrons and the physical mechanisms that lead to their precipitation into our atmosphere. I will also outline some of the key observations, both from space and from the ground, that shape the current debate on how this natural particle accelerator functions. This discussion leads to a University of Calgary project to monitor these mechanisms from the ground. The project is called ABOVE (the Array for Broadband Observations of VLF/ELF Emissions), and it incorporates an array of radio receivers in the Prairie Provinces that can simultaneously monitor energetic particle precipitation and also the electromagnetic waves that are believed to drive it.

Speaker: Dr. Chris Cully, Department of Physics and Astronomy, University of Calgary