Pulsating Reconnection in the interaction of two magnetic flux ropes

Two flux ropes (dia $=$ 7 cm, ds$=$ 3 cm, L $=$ 10m, I$_{\mathrm{rope}} = $ 300 A/rope) are generated by using a mask in front of a high emissivity cathode (n $=$ 4X10$^{12}$ cm$^{3}$, T$_{\mathrm{e-rope}}$ $=$ 8.5 eV) in a background magnetoplasma (He, B$_{\mathrm{oz}}=$ 330 G, n$=$1.0X10$^{12}$cm$^{3}$, T$_{\mathrm{e}} = $ 4 eV) in the LAPD device at UCLA. The ropes are kink unstable ( I \textgreater 250 A) but not violently so. All three components of the magnetic field were measured with small (1 mm dia) 3-axis probes sensitive to $\frac{\partial \vec{{B}}}{\partial t}$ and the plasma potential measured with an emissive probe. These were measured at 42,075 locations in the volume containing the ropes and 7000 time steps ($\delta \tau = $ .33 $\mu $s). The total electric field $\vec{{E}}=-\nabla \phi -\frac{\partial \vec{{A}}}{\partial t}$ and parallel resistivity as well as the Quasi Seperatrix layer (QSL) were derived from the data. The flux ropes periodically collide as they kink. Each time this happens a strong QSL (Q\textless 400) forms and the resistivity jumps to over a hundred times the classical value at locations within the QSL and also on the gradient of the rope current. The reconnection rate is directly evaluated by integrating the electric field along field lines as well as the energy deposition $\vec{{J}}\cdot \vec{{E}}$. The data indicate that there is more than one process causing the enhanced resistivity. The reconnection rate cannot be explained by conventional 2D theories.