ELECTROMAGNETIC EMISSIONS FROM A LASER-HEATED Z-PINCH PLASMA (MOLECULAR HELIUM)

The soft X-ray and visible electromagnetic emissions from a dense helium Z-pinch plasma were investigated with and without heating by a high power CO(,2) laser.; In the case of the unheated plasma, soft X-ray emission measurements were consistent with a thermalized plasma at a temperature of 30 eV. These measurements were performed by a foil-filtered photomultiplier tube which measured the frequency integrated soft X-ray emissions. Time resolved visible spectroscopic measurements were performed with a gated optical multichannel analyzer. During the pinch, the visible emissions were dominated by a strongly Stark broadened He II line at 468.6 nm. The width of that line corresponded to an electron density of 10('19) electrons/cm('-3), which agreed well with results from holographic interferometry. Line to continuum measurements for the He II 468.6 nm line also resulted in a electron temperature of between 20 and 30 eV.; In the afterglow of the discharge, radial spectra exhibited many molecular helium emission lines. Axial spectra were dominated by a bright continuum with many absorption bands. The absorption bands cannot be identified with helium, molecular helium nor impurities. The temporal behavior of several of these bands followed the intensity of the helium molecular bands and may be the first experimental evidence for helium molecular ion spectra.; In the case of the high power laser heating of the pinch plasma, the frequency integrated soft X-ray emissions were consistent with an inverse bremsstrahlung modified electron distribution, rather than a bi-Maxwellian distribution. The results of the soft X-ray measurements for the laser heated plasma indicated that the temperature was approximately 60-100 eV.