Ion Pickup by the Solar Wind Via Wave-Particle Interactions

  1. Alan Johnstone
  1. Peter H. Yoon and
  2. C. S. Wu

Published Online: 26 MAR 2013

DOI: 10.1029/GM061p0241

Cometary Plasma Processes

Cometary Plasma Processes

How to Cite

Yoon, P. H. and Wu, C. S. (1991) Ion Pickup by the Solar Wind Via Wave-Particle Interactions, in Cometary Plasma Processes (ed A. Johnstone), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM061p0241

Author Information

  1. Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742

Publication History

  1. Published Online: 26 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900278

Online ISBN: 9781118663660



  • Comets;
  • Space plasmas;
  • Astrophysics


Ion pickup by the solar wind is a topic of current interest. It has received much attention and has been discussed extensively in recent years, particularly after the cometary flybys. In situ observations and theoretical studies have enabled us to establish a fairly good understanding of the physics of ion pickup process. In a weakly turbulent solar wind, hydromagnetic waves that are either intrinsic or excited by the newborn ions can lead to pitch angle diffusion which may be approximately described by the quasi-linear theory with or without incorporating the resonance broadening mechanism due to weak turbulence. According to the weak turbulence theory, it is found that in general, the pickup ions do not form a complete spherical shell distribution in the time-asymptotic state, unless the wave field is sufficiently strong. In some cases, the ions can only possess a partial or incomplete shell. On the other hand, when the solar wind is highly turbulent, direct interaction between the wave fields and the newborn ions can result in rapid pitch angle scatteringwhich may lead to swift formation of a spherical shell distribution on the time scale of an ion gyro-period.