Fast Ion Transport by Magnetic Flux Ropes

Energetic Lithium test ions (500 $\le $ E$_{\mathrm{fast}}$ / T$_{\mathrm{i}} \quad \le $ 1000) are launched in a Helium plasma in the presence of current-produced magnetic flux ropes at the upgraded Large Plasma Device (LAPD) at UCLA. Perturbing flux ropes are introduced via a hot, biased LaB6 cathode in the main chamber.\footnote{B. Van Compernolle, Phys. of Plasmas. \textbf{19,} 102102 (2012).} Ion beam broadening up to fifty percent above background levels is observed in the radial direction after passing through the flux rope region (T$_{\mathrm{e,max}}=$7eV, B$_{\mathrm{perp}}=$7G, $\Delta $V$=$160V). Density, temperature, and magnetic fluctuation profiles are also obtained. A noise model has been developed to assess the quality of ion signals during the flux rope discharge period. The enhancement to transport may be a result of increased Coulomb scattering, magnetic fluctuations, or electric fields. Further analysis to determine the primary mechanism is ongoing.