Stabilization in the ZaP Flow Z-Pinch

The ZaP flow Z-pinch experiment at the University of Washington investigates the innovative plasma confinement concept of using sheared flows to stabilize an otherwise unstable configuration. The ZaP experiment generates an axially flowing Z-pinch that is 1 m long with a 1 cm radius with a coaxial accelerator coupled to a pinch assembly chamber. Magnetic probes measure the fluctuation levels of the azimuthal modes m = 1, 2, and 3. After assembly, the plasma is magnetically confined for an extended quiescent period where the mode activity is significantly reduced. Experimental measurements show a sheared flow profile that is coincident with the low magnetic fluctuations during the quiescent period. Recent experimental modifications produce more energetic Z-pinch plasmas that exhibit the same general behavior. The plasma equilibrium is characterized with a suite of diagnostics that measure the plasma density, magnetic field, ion and electron temperatures, in addition to plasma flow. The equilibrium is shown to satisfy radial force balance.