Theoretical studies have predicted that the $Z$-pinch can be stabilized with a sufficiently sheared axial flow [U. Shumlak and C. W. Hartman, Phys. Rev. Lett. 75, 3285 (1995)]. A $Z$-pinch experiment is designed to generate a plasma which contains a large axial flow. Magnetic fluctuations and velocity profiles in the plasma pinch are measured. Experimental results show a stable period which is over 700 times the expected instability growth time in a static $Z$-pinch. The experimentally measured axial velocity shear is greater than the theoretical threshold during the stable period and approximately zero afterwards when the magnetic mode fluctuations are high.

• Received 11 June 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.205005