Quantifying three dimensional reconnection in fragmented current layers

Abstract

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. There is growing evidence that when magnetic reconnection occurs in high Lundquist number plasmas such as in the Solar Corona or the Earth's Magnetosphere it does so within a fragmented, rather than a smooth current layer. Within the extent of these fragmented current regions, the associated magnetic flux transfer and energy release occur simultaneously in many different places. This investigation focusses on how best to quantify the rate at which reconnection occurs in such layers. An analytical theory is developed which describes the manner in which new connections form within fragmented current layers in the absence of magnetic nulls. It is shown that the collective rate at which new connections form can be characterized by two measures; a total rate which measures the true rate at which new connections are formed and a net rate which measures the net change of connection associated with the largest value of the integral of E jj through all of the non-ideal regions. Two simple analytical models are presented which demonstrate how each should be applied and what they quantify. V C 2015 AIP Publishing LLC.

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

“…Finding #3 in Table points out that the profiles of solar wind current sheets determine the high‐frequency magnetic spectra. As noted in Table , physical concepts that are important to the spatial profiles of current sheets are current sheet structuring (Gekelman et al, ; Ng et al, ; Schindler & Birn, ; Schindler & Hesse, ), plasma expansion and compression (Schindler & Hesse, , ), Bohm and gyro‐Bohm diffusion (Borovsky & Gary, ; Pecseli & Mikkelsen, ; Vahala & Montgomery, ), finite‐gyroradii effects (Schindler & Hesse, ), ion versus electron current carriers (Aunai et al, ; Sasunov et al, ; Schindler & Birn, ), Alfvén wave nonlinear processes (Gomberoff, ; Tsurutani et al, ), plasma waves in current sheets (Huang et al, ; Malaspina et al, ; Verscharen & Marsch, ; Zelenyi et al, ), pressure balance (Riazantseva et al, ; Tu et al, ; Zhang et al, ), and three‐dimensional reconnection (Huang & Bhattacharjee, ; Wyper & Hesse, ).…”

“…Journal of Geophysical Research: Space Physics (Riazantseva et al, 2005;Tu et al, 2016;Zhang et al, 2008), and threedimensional reconnection (Huang & Bhattacharjee, 2016;Wyper & Hesse, 2015).…”

Vortex line topology during vortex tube reconnection

“…The contour plots of Ψ allow us to estimate the vorticity flux that is reconnecting within each tube, by seeking local maxima and minima of Ψ -as described by [47]. These maxima and minima of Ψ can be combined to give different measures of the reconnected flux, which can be interpreted as the net and gross reconnection rates.…”

“…These maxima and minima of Ψ can be combined to give different measures of the reconnected flux, which can be interpreted as the net and gross reconnection rates. The net reconnection rate takes into account only the difference between the global maxima and minima of Ψ (dashed line, Figure 12), while the total, or gross, reconnection rate is obtained by examining adjacent local maxima and minima of Ψ -for a full discussion see [47]. Applying those techniques we find that the minimum measure of the flux reconnected is approximately equal to the total flux of a single vortex tube (note that this flux is 0.4 in non-dimensional code units).…”

Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

“…This partially results from sampling the reconnection rate in the jets at high cadence (D = t 2.5) only around the peak times of each jet, due to the impracticality of analyzing all of the data for the entire time series. In addition, fragmented 3D reconnection is the cumulative effect of many reconnection regions (Wyper & Jain 2013;Wyper & Hesse 2015), which smooths out the effect of a single burst of reconnection in the volume. Even so, the high-cadence sampling of the reconnection rate around the peaks also shows some intermittency, particularly for = L N 1.46.…”