Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Merging of magnetic islands as an efficient accelerator of electrons
AU - Tanaka, Kentaro G.
AU - Yumura, Tsubasa
AU - Fujimoto, Masaki
AU - Shinohara, Iku
AU - Badman, Sarah V.
AU - Grocott, Adrian
PY - 2010/10/7
Y1 - 2010/10/7
N2 - In a thin elongated current sheet, it is likely that more than one X-line forms and thus multiple magnetic islands are produced. The islands are then subject to merging. By simulating such a case with a two-dimensional full-particle code, we show that a merger forming a large island produces the most energetic electron population in the system. By setting the lateral extent of the simulation box to be as large as ∼ 100 ion inertial lengths, we introduce many (16) small islands in the initial thin current sheet ( ∼ 1 ion inertial length thickness). Merging of these islands proceeds to leave only two islands in the system. Then, strong electron acceleration is seen upon the final merger that produces the single island in the large simulation box. The most energetic electrons in the system are accelerated at the merging line. The merging line acceleration dominates because the reverse-reconnection facilitating the final merger is in such a strongly driven manner that the associated electric field is an order of magnitude larger than those available upon normal reconnection. Combining the results from additional runs enables us to obtain a scaling law, which suggests a non-negligible role played by merging lines in the observed electron acceleration phenomena.
AB - In a thin elongated current sheet, it is likely that more than one X-line forms and thus multiple magnetic islands are produced. The islands are then subject to merging. By simulating such a case with a two-dimensional full-particle code, we show that a merger forming a large island produces the most energetic electron population in the system. By setting the lateral extent of the simulation box to be as large as ∼ 100 ion inertial lengths, we introduce many (16) small islands in the initial thin current sheet ( ∼ 1 ion inertial length thickness). Merging of these islands proceeds to leave only two islands in the system. Then, strong electron acceleration is seen upon the final merger that produces the single island in the large simulation box. The most energetic electrons in the system are accelerated at the merging line. The merging line acceleration dominates because the reverse-reconnection facilitating the final merger is in such a strongly driven manner that the associated electric field is an order of magnitude larger than those available upon normal reconnection. Combining the results from additional runs enables us to obtain a scaling law, which suggests a non-negligible role played by merging lines in the observed electron acceleration phenomena.
KW - magnetic reconnection
KW - plasma simulation
KW - plasma transport processes
U2 - 10.1063/1.3491123
DO - 10.1063/1.3491123
M3 - Journal article
VL - 17
JO - Physics of Plasmas
JF - Physics of Plasmas
SN - 1070-664X
IS - 10
M1 - 102902
ER -