Taylor State Merging Studies: Experiment

We present the results of a series of experiments that investigate the dynamical merging of large aspect-ratio plasmas in the Swarthmore Spheromak Experiment (SSX) device. In SSX, two plasmas evolve and collide within a copper flux conserver with an aspect ratio of $\ell/R \cong 10$. Plasmas twist into relaxed Taylor states, with typical velocity $40~km/s$ , density $n_e = 0.5 \times 10^{16}~cm^{-3}$, proton temperature $T_i \approx 20~eV$, and magnetic field $B \approx 0.4~T$. As the plasmas collide, measurements of interest are line-averaged plasma density, fluid-scale vector B-field (distance between probes $\sim 32~\rho_i$, and plasma temperature, acquired via Helium-Neon interferometry, a 2D $4\times4$ grid array of B-dot probes, and Ion-Doppler Spectroscopy (IDS) respectively. We compare measured data to Dedalus-framework simulations (see S. Yang et al this session). We merge Taylor State configurations of both co- and counter-helicity (either with the same or opposite directions of twist). We observe appreciable ion heating, consistent with magnetic reconnection. Finally, we discuss the suitability of merged Taylor states for use as Magneto-Inertial Fusion (MIF) targets.