Flow profile measurement with a Mach probe in the open-field line region of C-2W

In TAE Technologies' current experimental device, C-2W (also called ``Norman'')~[1], record-breaking, advanced beam-driven field-reversed configuration (FRC) plasmas are produced and sustained in steady-state utilizing variable energy neutral beams, advanced divertors, end bias electrodes, and an active plasma control system.~The end biasing plays an important role by heating the FRC plasma, stabilizing global MHD modes, and suppressing turbulence with an ExB sheared flow in the open-field line region.~To study this biasing effect, a combo probe (Mach and Triple Langmuir probes) has been installed in the open-field line region of the C-2W confinement vessel to measure the ion flow outside the FRC separatrix.~This probe has the capability to measure~parallel and~perpendicular flows as well as electron temperature and density at the same location. In addition, radial electric field can be estimated by scanning the floating potential in a radial direction. Experimental setup and results will be presented. [1]~H. Gota~\textit{et al}., Nucl. Fusion~\textbf{59}~112009 (2019).