Experimental Plasma Flow into a Vacuum Magnetic Cusp Field

A directed dense plasma has been observed to penetrate and be detained by a vacuum cusp magnetic field. A gross measurement of the directed velocity of the deuterium plasma was (8.5±0.5)×${10}^6$ cm/sec. Ion density in the central region of the cusp was measured to be 8.5×${10}^{15}$ at 16 μsec after injection and had a decay constant of 13.5 μsec. Magnetic probe measurements are shown which indicate the gross reaction of the magnetic field to the injected plasma. Observation of impurity emission indicates that the plasma electrons cool rapidly and that the collision-dominated plasma is in contact with the container walls at the cusp ring.