Experimental study of fast fluctuations and turbulence during magnetic reconnection events on the VTF experiment

We present measurements of electrostatic fluctuations during reconnection events on the VTF experiment at MIT. Because we have found a regime in VTF where the reconnection is ``bursty'' in time [1], it is an ideal experiment for answering the long-standing question of whether current-driven turbulence plays an important role in the reconnection process. Our measurement system consists of high-bandwidth, impedance-matched Langmuir probes, digitized by a fast oscilloscope. Broadband fluctuations are observed, extending up to $f_{ce}$ ($\simeq$~1.5~GHz, $f_{pe}/f_{ce} \simeq 10$), coincident with reconnection events both in time and space. Arrays of probes and standard cross-correlation analysis provide wavelength measurements. Non-linear phenomena, such as discrete positive potential spikes, traveling at $\sim$2-3~v$_{te}$ and with spatial width 1-2~mm ($\simeq 50-100~\lambda_{De}$) are also observed coincident with large reconnection events. Finally, we will discuss various instability mechanisms, with insight from a recently-installed electron energy analyzer.\\[1ex] [1] J. Egedal, \textit{et al}. (2007). PRL \textbf{98}, 015003.