Figure 4
From: Direct observations of pure electron outflow in magnetic reconnection
Local magnetic field inversion associated with plasmoid. (a,b) A schematic illustrating the relation between magnetic field (B in red) and time derivative of magnetic field (\(\partial B/\partial t\) in blue) in bipolar and unipolar magnetic field, respectively. When the sign of magnetic field inverts (a), the signal of \(\partial B/\partial t\) is tripolar. On the other hand, when a Biermann magnetic field approaches and passes through the probe (b), the signal of \(\partial B/\partial t\) is bipolar. (c,d) Magnetic field measurements with and without the applied magnetic field in case2, respectively. The plots show the \(B_2\) component where the magnetic field inversion is most significant. The blue and red curves represent the measured voltage and magnetic field, respectively. The velocity of fast plasma is \(\sim 500\) km/s7, thus, the signal before 100 ns is attributed to be the electromagnetic noise. This region (\(t<{100}\,\hbox {ns}\)) is shaded gray. The voltage curves at \(t\sim {200}\,\hbox {ns}\) briefly saturate. The magnetic field before the saturation is expressed as dotted red curves and our analysis likely underestimates the \(B_2\) magnetic field before saturation. The dotted and solid horizontal lines represent the initial magnetic field strength and \(B=0\), respectively. The voltage returns to 0 at the end of the trace. We integrate the signals from the end of time to avoid problems caused by noise and saturation at times before \(\sim {250}\,{\hbox {ns}}\).
