Vacuum Ultraviolet Emission from a Neon-Seeded Theta Pinch

摘要

Plasma properties and line radiation were observed with a high-density θ pinch filled with a few torr of deuterium or helium, seeded with several percent neon. The 0 pinch, driven by a 60-kV, 180-kJ capacitor bank, achieves 90 kG, within a 3-usec quarter period, in a 25-cm-long, 8.2-cm-i.d. 6 coil. The predominant emission is in the 50- to 200-A vacuum ultraviolet range. Most of the strong lines of Ne VI, Ne VII, and Ne VIII identified by others were observed on SWR or SC-7 film with a 2.2-m vacuum grazing incidence spectrograph. Radial-view spectra taken through a radial hole at the center of the 6 coil indicate a more homogeneous plasma temperature than those spectra taken axially. The He II 4686-A line profile and nearby continuum were observed with a monochromator and photomultiplier, compared with theoretical calculations, and used to obtain electron temperature and density values. A typical case for He + 2% Ne at about 1 torr yields ~40 eV at ~6 x 1017 e/cm3. This plasma was observed by laser holography and exhibits excellent containment for about 1.0 usec-the time of the line-profile measurements-but is followed immediately by apparently severe instabilities.