Plasma Studies in the SPECTOR Experiment as Target Development for MTF

General Fusion (GF) is developing a Magnetized Target Fusion (MTF) concept in which magnetized plasmas are adiabatically compressed to fusion conditions by the collapse of a liquid metal vortex. To study and optimize the plasma compression process, GF has a field test program in which subscale plasma targets are rapidly compressed with a moving flux conserver. GF has done many field tests to date on plasmas with sufficient thermal confinement but with a compression geometry that is not nearly self-similar. GF has a new design for our subscale plasma injectors called SPECTOR (for SPhErical Compact TORoid) capable of generating and compressing plasmas with a more spherical form factor. SPECTOR forms spherical tokamak plasmas by coaxial helicity injection into a flux conserver (a$=$ 9 cm, R$=$ 19 cm) with a pre-existing toroidal field created by \textasciitilde 0.5 MA current in an axial shaft. The toroidal plasma current of 100 - 300 kA resistively decays over a time period of \textasciitilde 1.5 msec. SPECTOR1 has an extensive set of plasma diagnostics including Thomson scattering and polarimetry. MHD stability and lifetime of the plasma was explored in different magnetic configurations with a variable safety factor q($\Psi )$.~ Relatively hot (T$_{e\, }\ge $ 350 eV) and dense (\textasciitilde 10$^{20}$ m$^{-3})$ plasmas have achieved energy~confinement times $\tau _{E}\ge $100$\mu $sec and are now ready for field compression tests.