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Title: Collisionless Reconnection Research at CMSO

Abstract

No abstract prepared.

Authors:
Publication Date:
Research Org.:
Univeristy of New Hampshire
Sponsoring Org.:
USDOE
OSTI Identifier:
902429
Report Number(s):
DOE/ER/54824-1
TRN: US0703533
DOE Contract Number:
FG02-05ER54824
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MAGNETIC RECONNECTION; RESEARCH PROGRAMS; PLASMA

Citation Formats

Amitava Bhattacharjee. Collisionless Reconnection Research at CMSO. United States: N. p., 2007. Web. doi:10.2172/902429.
Amitava Bhattacharjee. Collisionless Reconnection Research at CMSO. United States. doi:10.2172/902429.
Amitava Bhattacharjee. Fri . "Collisionless Reconnection Research at CMSO". United States. doi:10.2172/902429. https://www.osti.gov/servlets/purl/902429.
@article{osti_902429,
title = {Collisionless Reconnection Research at CMSO},
author = {Amitava Bhattacharjee},
abstractNote = {No abstract prepared.},
doi = {10.2172/902429},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Apr 20 00:00:00 EDT 2007},
month = {Fri Apr 20 00:00:00 EDT 2007}
}

Technical Report:

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  • The final years of this grant have been dedicated to diagnosing the observable properties of Collisionless Magnetic Reconnection (CMR) as disclosed by the open boundary condition PIC simulations developed under this grant. Particular attention has focussed on identifying the Electron Diffusion Region (EDR), the short scale domain where the process is thought to be enabled. The critical issue has been the need for experimental closure for CMR that is widely invoked in astrophysics, but has actually rather little direct, incontrovertible evidence for its involvement. This difficulty arises because CMR is about topology change of the magnetic field - a conceptmore » that is not conducive to single, or even few point correlations as are beginning to be possible with spacecraft armada, like Cluster or the planned Magnetospheric Multi-Scale (MMS) mission to be launched in 2014. Alternate formulations about the time rate of magnetic flux inventoried by a moving observer, reformulate the needed evidence in terms of the curl of various weak vector fields, such as E+UexB, that is zero in ideal MHD. To sense E+UexB from space measurements is already a heroic task. The curl of such a small vector field is outside the domain of the possible.« less
  • The ion dynamics in a collisionless magnetic reconnection layer are studied in a laboratory plasma. The measured in-plane plasma potential profile, which is established by electrons accelerated around the electron diffusion region, shows a saddle-shaped structure that is wider and deeper towards the outflow direction. This potential structure ballistically accelerates ions near the separatrices toward the outflow direction. Ions are heated as they travel into the high pressure downstream region.
  • The Grant DE-FG-02-00ER54712, ?Experimental Studies of Collisionless Reconnection Processes in Plasmas?, financed within the DoE/NSF, spanned a period from September , 2003 to August, 2007. It partly supported an MIT Research scientist, two graduate students and material expenses. The grant enabled the operation of a basic plasma physics experiment (on magnetic reconnection) at the MIT Plasma Science and Fusion Center and the MIT Physics Department. A strong educational component characterized this work throughout, with the participation of a large number of graduate and undergraduate students and interns to the experimental activities. The study of the collisionless magnetic reconnection constituted themore » primary work carried out under this grant. The investigations utilized two magnetic configurations with distinct boundary conditions. Both configurations were based upon the Versatile Toroidal Facility (VTF). The first configuration is characterized by open boundary conditions where the magnetic field lines interface directly with the vacuum vessel walls. The reconnection dynamics for this configuration has been methodically characterized and it has been shown that kinetic effects related to trapped electron trajectories are responsible for the high rates of reconnection observed [7]. This type of reconnection has not been investigated before. Nevertheless, the results are directly relevant to observations by the Wind spacecraft of fast reconnection deep in the Earth magnetotail [9]. The second configuration was developed to be specifically relevant to numerical simulations of magnetic reconnection, allowing the magnetic field-lines to be contained inside the device. The configuration is compatible with the presence of large current sheets in the reconnection region and reconnection is observed in fast powerful bursts. These reconnection events facilitate the first experimental investigations of the physics governing the spontaneous onset of fast reconnection [12]. In this Report we review the general motivation of this work, the experimental set-up, and the main physics results. The details of the individual chapters are naturally contained in the relevant publications [1-12], indicated in the reference list and annexed to this Report.« less