Correlation of Measured Soft X-Ray Pulses With Modeled Dynamics of the Plasma Focus

The six-phase Lee model code is used to fit the computed
current waveform to the measured current waveform of
INTI plasma focus (PF; 2.2 kJ at 12 kV), a T2 PF device, operated
as a source of neon soft X-ray (SXR) with optimum yield around
2 torr of neon. The characteristic He-like and H-like neon line
SXR pulse is measured using a pair of SXR detectors with selected
filters that, by subtraction, has a photon energy window of 900
to 1550 eV covering the region of the characteristic neon SXR
lines. From the analysis of the fitted current and the measured
SXR pulses, the characteristic neon SXR pulses are correlated
to the pinch dynamics, and the subsequent slightly harder SXR
pulses are correlated to the anomalous resistance phase. The characteristic
neon SXR yield is measured; the pulse has a duration of
25 ns. The characteristic neon SXR typically starts 10 ns before
the pinch phase and continues through the end of the 10-ns pinch
phase, tailing into the anomalous resistance phase. Harder SXR
pulses, probably Bremsstrahlung, are correlated to the anomalous
resistance phase, with the main pulse occurring nearly 200 ns after
the characteristic neon SXR pulse.