Plasma Experiments with a Three-Meter θ Pinch

Measurements are reported on the plasma produced in an 830-kJ theta pinch (scylla IV) with a 3-m compression coil in which the compression field is extended to 120 μsec by means of “crowbar” switches. Double-exposure holographic interferometry, side-on streak photographs, and neutron-emission measurements establish the following comparison with the previous version of the experiment: (1) The plasma confinement time and neutron emission have been extended from 3 to 10 μsec. (2) The scaling of confinement time and plasma temperature from the 1-m device is accounted for by simple end-loss and shock-compression considerations. (3) An m = 1 “wobble”of the plasma column is observed in the present experiment and is interpreted in terms of plasma rotation propagating from the ends at approximately the Alfvén speed.