Nonlinear Alfv\'{e}n wave interactions in the Large Plasma Device

The nonlinear dynamics of large amplitude Alfv\'{e}n waves are believed to play a major role in the evolution of the macroscopic properties of numerous laboratory plasmas and astrophysical systems. However, despite their importance the nonlinear dynamics of these fluctuations remains a point of great controversy with few prior experimental measurements. Nonlinear interactions between Alfv\'{e}n waves are being studied \footnote[2]{T.A. Carter, B. Brugman, P. Pribyl and W. Lybarger, Phys. Rev. Lett. 96, 155001 (2006)} in the Large Plasma Device Upgrade (LAPD) at UCLA, using large amplitude, $\delta B / B_{0} \sim 1 \%$, waves generated by LAPD's Alfv\'{e}n wave MASER or by antennas. In these experiments the interaction of two co-propagating large amplitude shear Alfv\'{e}n waves is extensively studied. The nonlinear generation of density fluctuations at the beat frequency along with the formation of numerous discrete Alfv\'{e}nic sidebands has been observed using both wave launching mechanisms over a broad range of plasma parameters and launch wave frequencies. Detailed measurements of these interactions and comparisons with a nonlinear Braginskii fluid calculation will be presented. Preliminary results from counter-propagating Alfv\'{e}n wave interaction experiments will also be discussed.