Double Star TC-1 observation of the earthward flowing plasmoids in the near magnetotail

We analyze Double Star TC-1 magnetic field data from July to September in 2004 and find that plas-moids exist in the very near-Earth magnetotail. It is the first time that TC-1 observes the plasmoids inthe magnetotail at X > ?13 RE. According to the difference of the magnetic field structure in plasmoids,we choose two typical cases for our study: the magnetic flux rope on August 6 with the open magneticfield and the magnetic loop on September 14 with the closed magnetic field. Both of the cases are as-sociated with the high speed earthward flow and the magnetic loop is related to a strong substorm. Theions can escape from the magnetic flux rope along its open field line, but the case of the closed mag-netic loop can trap the ions. The earthward flowing plasmoids observed by TC-1 indicate that the mul-tiple X-line magnetic reconnection occurs beyond the distance of X=?10 RE from the earth.

We analyze Double Star TC-1 magnetic field data from July to September in 2004 and find that plasmolds exist in the very near-Earth magnetotaih It is the first time that TC-1 observes the plasmoids in the magrnetotail at X 〉 -13 RE. According to the difference of the magnetic field structure in plasmoids, we choose two typical cases for our study： the magnetic flux rope on August 6 with the open magnetic field and the magnetic loop on September 14 with the closed magnetic field. Both of the cases are as sociated with the high speed earthward flow and the magnetic loop is related to a strong substorm. The ions can escape from the magnetic flux rope along its open field line, but the case of the closed magnetic loop can trap the ions. The earthward flowing plasmoids observed by TC-1 indicate that the multiple X-line magnetic reconnection occurs beyond the distance of X=-10 RE from the earth.