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Title: Particle acceleration in cosmic plasmas – paradigm change?

The presentation begins by considering the requirements on the acceleration mechanism. It is found that at least some particles in high-energy sources are accelerated by magnetic reconnection (and not by shocks). The two paradigms can be distinguished by the hardness of the spectra. Shocks typically produce spectra with p > 2 (relativistic shocks have p ~ 2.2); non-linear shocks & drift acceleration may give p < 2, e.g. p=1.5; B-field dissipation can give p = 1. Then collapse of stressed magnetic X-point in force-free plasma and collapse of a system of magnetic islands are taken up, including Island merger: forced reconnection. Spectra as functions of sigma are shown, and gamma ~ 109 is addressed. It is concluded that reconnection in magnetically-dominated plasma can proceed explosively, is an efficient means of particle acceleration, and is an important (perhaps dominant for some phenomena) mechanism of particle acceleration in high energy sources.
 [1] ;  [2]
  1. Purdue University
  2. Los Alamos National Laboratory
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
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Resource Relation:
Conference: Plasma Energization: Exchanges between Fluid and Kinetic Scales ; 2015-05-04 - 2015-05-06 ; Los Alamos, New Mexico, United States, Melbourne (Australia), 19-25 Apr 2015
Research Org:
Los Alamos National Laboratory (LANL)
Sponsoring Org:
Purdue University
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS Astronomy and Astrophysics