### 抄録

We address the unsolved question of how foreshock field-aligned beam (FAB) parallel temperatures are produced. Studies including numerical simulations and recent observations have indicated that shocks can be nonstationary and include embedded spatial structures with varied scales. As a first step towards assessing the impact of such variability on backstreaming ions, we examine how a randomly distributed shock normal direction will affect FAB parallel velocity (v_{||}) distributions. Assuming that the FABs are produced in a quasi-adiabatic reflection process at the shock, we derive a probability distribution function for v_{||}. These derived distributions exhibit second, third and fourth order moments that agree well with the observations for a large range of reflection efficiencies δ, and depend strongly upon the average angle between the magnetic field and the shock normal θ_{Bn0}. Best agreement is obtained for fluctuations of the normal orientation of a few degrees about a nominal direction. The derived model predicts a strong correlation between the shock geometry (θ_{Bn0}) and the moments of the parallel velocity distribution, but with stronger tails extending to higher values of θ_{Bn0}, a trend opposite to the observations.

元の言語 | 英語 |
---|---|

ページ（範囲） | 349-362 |

ページ数 | 14 |

ジャーナル | Astrophysics and Space Science Proceedings |

発行部数 | 202469 |

DOI | |

出版物ステータス | 出版済み - 1 1 2010 |

イベント | 15th Workshop on Cluster Active Archive, 2008 - Tenerife, Canary Islands, スペイン 継続期間: 3 9 2008 → 3 15 2008 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)
- Computer Science Applications
- Spectroscopy
- Space and Planetary Science
- Nuclear and High Energy Physics

### これを引用

*Astrophysics and Space Science Proceedings*, (202469), 349-362. https://doi.org/10.1007/978-90-481-3499-1_23

**Effect of shock normal orientation fluctuations on field-aligned beam distributions.** / Meziane, K.; Hamza, A. M.; Wilber, M.; Lee, M. A.; Mazelle, C.; Lucek, E. A.; Hada, Tohru; Markowitch, A.

研究成果: ジャーナルへの寄稿 › Conference article

*Astrophysics and Space Science Proceedings*, 番号 202469, pp. 349-362. https://doi.org/10.1007/978-90-481-3499-1_23

}

TY - JOUR

T1 - Effect of shock normal orientation fluctuations on field-aligned beam distributions

AU - Meziane, K.

AU - Hamza, A. M.

AU - Wilber, M.

AU - Lee, M. A.

AU - Mazelle, C.

AU - Lucek, E. A.

AU - Hada, Tohru

AU - Markowitch, A.

PY - 2010/1/1

Y1 - 2010/1/1

N2 - We address the unsolved question of how foreshock field-aligned beam (FAB) parallel temperatures are produced. Studies including numerical simulations and recent observations have indicated that shocks can be nonstationary and include embedded spatial structures with varied scales. As a first step towards assessing the impact of such variability on backstreaming ions, we examine how a randomly distributed shock normal direction will affect FAB parallel velocity (v||) distributions. Assuming that the FABs are produced in a quasi-adiabatic reflection process at the shock, we derive a probability distribution function for v||. These derived distributions exhibit second, third and fourth order moments that agree well with the observations for a large range of reflection efficiencies δ, and depend strongly upon the average angle between the magnetic field and the shock normal θBn0. Best agreement is obtained for fluctuations of the normal orientation of a few degrees about a nominal direction. The derived model predicts a strong correlation between the shock geometry (θBn0) and the moments of the parallel velocity distribution, but with stronger tails extending to higher values of θBn0, a trend opposite to the observations.

AB - We address the unsolved question of how foreshock field-aligned beam (FAB) parallel temperatures are produced. Studies including numerical simulations and recent observations have indicated that shocks can be nonstationary and include embedded spatial structures with varied scales. As a first step towards assessing the impact of such variability on backstreaming ions, we examine how a randomly distributed shock normal direction will affect FAB parallel velocity (v||) distributions. Assuming that the FABs are produced in a quasi-adiabatic reflection process at the shock, we derive a probability distribution function for v||. These derived distributions exhibit second, third and fourth order moments that agree well with the observations for a large range of reflection efficiencies δ, and depend strongly upon the average angle between the magnetic field and the shock normal θBn0. Best agreement is obtained for fluctuations of the normal orientation of a few degrees about a nominal direction. The derived model predicts a strong correlation between the shock geometry (θBn0) and the moments of the parallel velocity distribution, but with stronger tails extending to higher values of θBn0, a trend opposite to the observations.

UR - http://www.scopus.com/inward/record.url?scp=80455137759&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80455137759&partnerID=8YFLogxK

U2 - 10.1007/978-90-481-3499-1_23

DO - 10.1007/978-90-481-3499-1_23

M3 - Conference article

AN - SCOPUS:80455137759

SP - 349

EP - 362

JO - Astrophysics and Space Science Proceedings

JF - Astrophysics and Space Science Proceedings

SN - 1570-6591

IS - 202469

ER -