Overview of the C-2 Field-Reversed Configuration Experimental Program and Future Plan on C-2 Upgrade

C-2 is the world's largest compact-toroid (CT) device at Tri Alpha Energy that produces field-reversed configuration (FRC) plasmas by colliding/merging oppositely-directed CTs and seeks to study the evolution, heating and sustainment effects of neutral-beam (NB) injection into FRCs [1, 2]. Recently, significant progress has been made in C-2 on both technology and physics fronts, achieving $\sim$ 5 ms stable plasmas with a dramatic improvement in confinement. FRCs are stabilized with an edge biasing using end-on plasma-guns and/or electrodes, and are partially sustained with NB injection (20 keV Hydrogen, $\sim$ 4 MW). Recent work to reduce scrape-off layer and radiative losses has succeeded in reducing the average power balance deficit to $\sim$ 1.5 MW. Increasing plasma pressure and electron temperature are now observed during brief periods of the discharge, which indicate a sign of NB injection effect such as accumulating fast-ions as well as heating core/edge plasmas. Highlights of these advances, broader C-2 experimental program, and future plan on upgrading the C-2 device with new NBs (15 keV, up to 10 MW injection power, selectable beam injection angle) will be presented. \\[4pt] [1] M.W. Binderbauer \textit{et al.}, Phys. Rev. Lett. \textbf{105}, 045003 (2010).\\[0pt] [2] M. Tuszewski \textit{et al.}, Phys. Rev. Lett. \textbf{108}, 255008 (2012).