Existing propulsion technologies are limited in terms of either fuel efficiency or thrust. Chemical rockets, although powerful and capable of producing large thrust, are fuel inefficient for long missions that require high delta-v. Solar-powered electric propulsion could be relatively fuel efficient (with specific impulse up to several thousands of seconds) but produces only small thrust. Fast plasmoid-mediated Magnetic Reconnection (MR) has been proposed for space propulsion in which magnetic energy is directly converted to kinetic energy. Several laboratory experiments including Magnetic Reconnection Experiment (MRX) and FLARE (soon to come online) at PPPL and Terrestrial Reconnection Experiment (TREX) at UW-Madison have also been dedicated for fundamental studies of the magnetic reconnection process, including the rate at which magnetic field lines break to reconnect. These experiments do primarily operate in the relatively high beta (weak magnetic field) and collisionless regimes relevant to space and astrophysical plasmas. However, laboratory investigation of weakly collisional (and collisional) regimes is very limited. Here we propose to investigate this particular regime of magnetic reconnection in a laboratory setting. The proposed research would help us understand the collective ion kinematics from the reconnection site as well as exploiting wide applications for broader plasma science including plasma propulsion. We propose to first measure ion outflows in TREX, utilizing the combination of the Mach probe data and fast camera images. Second, we will vary and control the specific impulse over a wide range by modifying the magnetic field strength applied (with and without guide field) and the plasma density. In the MHD/collisional limit the dependency of global exhaust velocity will be tested by utilizing a wide range of gases and plasma densities. The high-density limit will be achieved by adding more plasma gun sources in TREX as well as utilizing the planar plasma source of the Wisconsin Plasma Physics Laboratory (WiPPL) at UW-Madison.
