Time-Resolved L-Shell Spectra from Ions with Z=40-47 in Two and Four Wire X Pinches

Summary form only given. Time-resolved L-shell X-ray spectra from single X pinches at 400 kA, and two X pinches in parallel, each with about 225 kA, have been obtained from medium Z materials (Z=40-47). This was accomplished using a new, specially designed Kentech X-ray streak camera combined with a focusing spectrograph with spatial resolution (FSSR) mica crystal spectrograph. The experiments were carried out on the 450 kA, 100 ns (full width at half maximum) XP pulser at Cornell University. A very short delay triggering system makes it possible to record the beginning of an X-ray burst with a temporal resolution of about 10 ps. The streak camera sweep is triggered either by the UV generated during the X-pinch breakdown process or by the XUV pulse radiated just before the main X-ray pulse. An X-ray pulse from an X pinch usually begins with a strong burst of continuum radiation. After a very short time, on the order of tens of ps, the continuum burst will subside, and radiation from the spectral lines of Ne-like ions will appear. This line radiation will continue for the remainder of the overall X-ray output pulse, becoming superimposed upon any subsequent continuum bursts that should occur. Line widths were observed to change with time, indicating a change in ion velocity and/or plasma density. There was no evidence of energetic electrons in the initial part of the X-ray pulse. In fact, spectral lines corresponding to transitions in relatively cold, weakly ionized wire material, and excited by electrons with energies of more than 10 keV, were generally observed in the X-ray radiation more than 100 ps after the initial "thermal" X-ray burst. The fine structure of Ne-like spectra along the isoelectronic sequence for Z=40-47 is currently being investigated