Time Resolved X-ray Fine Structures, Neutron Emission, and Ion Velocities in a Fast 1 kJ Plasma Focus
One to four (mostly 2) X-ray spot structures are present in hydrogen and deuterium along the z-axis during the dense pinch phase; approximately 4% argon is required for soft radiation pin hole photography. Spots have an observed 5 to 10 ns lifetime and develop in succession within the first 30 ns of the X-ray emission. The hard 80 > keV radiation shows the spot time structure which controls the neutron pulse. The X-ray spots represent m = 0 plasma instabilities.
The neutron energy spectrum emitted during the dense pinch phase (2 x 108 n per shot) was determined from 30 m flight histograms. The neutron producing runway ions (plasma temperature ~ 1 keV) have an average 100–120 keV energy within a 15–25 degree beam angle to the z-axis when the target beam model is applied in the theoretical analysis.
Experimental magnetic analysis of the ion beam results in an ion energy spectrum between 50–150 keV. The neutrons are produced at the far end of the focus and beyond within about 4 cm distance from the front face of the center electrode. This is shown directly by neutron cut-off.