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Particle acceleration in collisionless shock with large scale magnetic field variation

Particle acceleration in collisionless shock with large scale magnetic field variation. Fan Guo, J. R. Jokipii and Jozsef Kota Lunar & Planetary Laboratory, Department of Planetary Sciences University of Arizona. Presentation at SHINE meeting, July 27th 2010.

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Particle acceleration in collisionless shock with large scale magnetic field variation

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  1. Particle acceleration in collisionless shock with large scale magnetic field variation Fan Guo, J. R. Jokipii and Jozsef Kota Lunar & Planetary Laboratory, Department of Planetary Sciences University of Arizona Presentation at SHINE meeting, July 27th 2010

  2. Large scale shocks associated with magnetic field variation Termination Shock

  3. Diffusive shock acceleration (DSA; Krymsky 1977, Axford et al. 1977, Bell 1978, Blandford & Ostriker 1978), is the most popular theory for charged-particle acceleration. The basic conclusions of DSA can be drawn from the Parker transport equation (Parker 1965) by considering the shock to be a compressive discontinuity in an infinite one-dimensional and time steady system. DSA is thought to be the mechanism that accelerates anomalous cosmic rays (ACRs) in the Heliospheric termination shock and also SEPs with energy up to GeV in CME shocks. advectiondiffusion drift energy change

  4. Cummings (2008)

  5. Some consideration • Florinski • Jokipii • Kota • Schwadron Schwadron & McComas (2006) Florinski & Zank (2006)

  6. Kota & Jokipii (2008)

  7. Some possibility (spatial source variation) Jokipii & Kota (2008)

  8. A simple illustrative model Kota 2008, 2010 submitted

  9. Basic consideration • Consider a sinusoidal magnetic field variation Bx = Bx0sin(kx), Bz = Bz0 • Solve transport equation using stochastic integration • Spatial units are in 10 AU, time units are in about 1 month. Upstream velocity is 500 km/s, with a strong compression ratio (r=4.) at the shock. k┴/k|| = 0.05.

  10. P = 3.0 P0 P = 10.0 P0

  11. Slide from Alan Cummings, ISSI Workshop

  12. For oblique shocks and smaller fluctuation amplitude

  13. Conclusions • After the consideration of large scale magnetic field variation, the 1-D diffusive shock acceleration will be significantly altered. • The charged particles will be trapped and accelerated in the regions where the foot points converging each other, creating ‘hot spot’ of accelerated particles. • The particles would transport towards ‘hot spot’ region and get accelerated, as a consequence of particle transport.

  14. Thanks for your attention!

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