We study the features of the magnetic field variations within the 2011 June 7 eruptive event that includes a large filament eruption, a flare, and a CME formation. The magnetic field characteristics were obtained by using vector measurements of the magnetic field with the SDO/HMI and 3D magnetic field calculations based on nonlinear force-free field (NLFFF) modeling. Strong and relatively fast variations in the photospheric field characteristics after the flare onset are shown to be observed only within a small site (\(20''\times 20''\)) of the eruption region in the neighborhood of the polarity inversion line (PIL).We found that the magnetic field strength, the electric current density, current helicity density and free magnetic energy density above this region are growing with height reaching their maximums at the level of ∼15 Mm. After 2011 July 7 00:00 UT, this height started gradually reducing.The NLFFF extrapolation revealed the presence of a magnetic flux rope elongated approximately along the main PIL and an arcade of magnetic field lines over it. The flux-rope axis is located at height of ∼15 Mm. The flux-rope footpoints approximately coincide with the eruptive filament footpoints. Thus, we concluded that the detected flux rope is associated with the magnetic structure of the observed filament. The detected strong variation of the magnetic field within the eruption region are most probably associated with the magnetic field reconfiguration after the filament eruption. The \(T_{n}\) parameter, which is the average magnetic field twist within the flux rope, was found to increase up to 2.5 rotations before the flare onset, and to dramatically decrease afterward. This may reflect the developing of kink instability that presumably triggered this eruption.

中文翻译：

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使用非线性自由力场模型研究伴随2011年6月7日爆发事件的磁场变化

我们研究了2011年6月7日爆发事件中磁场变化的特征，其中包括大的细丝喷发，爆发和CME形成。通过使用带有SDO / HMI的磁场矢量测量和基于非线性无力场（NLFFF）建模的3D磁场计算，获得磁场特性。耀斑发作后光球场特性的强烈且相对较快的变化显示仅在一个较小的位置（\（20''\乘以20''\）才能观察到我们发现在该区域上方的磁场强度，电流密度，电流螺旋强度和自由磁能密度都随着高度的增加而增大，在该区域的极性反转线（PIL）附近。水平约为15毫米。在2011年7月7日00:00 UT之后，该高度开始逐渐减小。NLFFF外推显示存在一条沿主PIL大致拉长的磁通量绳索，以及在其上方的磁力线拱廊。磁通线轴位于〜15 Mm的高度。助焊剂绳脚点大约与喷出的灯丝脚点重合。因此，我们得出结论，检测到的通量绳与所观察到的细丝的磁性结构有关。在喷发区域内检测到的强磁场变化很可能与灯丝喷发后的磁场重构有关。的\（T_ {n} \）参数，即磁通绳内的平均磁场扭曲，被发现在耀斑发作之前增加至2.5圈，之后急剧减少。这可能反映了扭结不稳定性的发展，大概引发了这种喷发。