SPACE AND COSMIC RAY PHYSICS SEMINAR

University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, May 2, 2011
Coffee, Tea & Snacks 4:15-4:30 PM

Chee K. Ng
George Mason University, Fairfax, VA
Effects of Self-Amplified Alfvén Waves in the Shock Acceleration and Transport of Solar Energetic Particles

A number of intriguing solar energetic particle (SEP) observations, both old and new, are best understood in terms of the resonant interaction between streaming SEPs and self-amplified Alfvén waves. These observations include an apparent “streaming limit” to SEP intensities, complex temporal and event-to-event variations of SEP elemental abundances, and flattening of SEP energy spectra. I will review theoretical modeling of SEP interplanetary transport and acceleration that includes self-amplified Alfvén waves and to what extent the models are able to quantitatively explain the observations. I will describe how, in a coronal shock acceleration model, self-amplified waves bootstrap particle acceleration at a CME-driven shock. In addressing the observed dynamic behavior of the SEPs, it is essential that the models include time-dependence and pitch-angle dependence in wave-particle interaction. It is also important to appreciate how waves excited by SEPs of one species, energy, or rigidity affect SEPs of a different energy, species, or rigidity. Taken together, the observations and theoretical results provide strong and persuasive support for the presence and importance of self-amplified waves in large gradual SEP events. Supported by NASA Grants NNX09AU98G


Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Catha Stewart at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.