Turbulence Parallel Wavenumbers in the Texas Helimak

It is well known that wavenumbers, in particular the existence of a parallel wavenumber, play an important role in the classification of turbulence. In a paper published in 2010, Paolo Ricci and B.N. Rogers posit the existence of a previously undiscovered resistive interchange mode, similar to a tokamak resistive ballooning instability, that appears in simple magnetized toroidal plasmas at long connection length (PRL 104, 145001). As the pitch of the magnetic field lines is flattened, and thus the connection length is increased, the system was shown to undergo a transition from an ideal interchange mode with zero parallel wavenumber to a resistive interchange mode with nonzero parallel wavenumber. Additionally, the system undergoes a change in mode numbers. In this work we seek to measure the parallel wavenumber in the Texas Helimak at several long connection lengths in order to characterize the turbulence. By so doing we attempt to find the resistive interchange mode to provide verification of its existence in the Texas Helimak.