Multiarc Generator
A multiarc generator, comprised of stacked metal contact disks, has been tested. Arc formation occurred in the gaps between each cylindrically shaped contact piece during 3-to 30-kA discharges through various stacked disk configurations. Severe current limiting was demonstrated by stacked disks whose axial length was less than their diameter. Current extinction time periods for discharges through the stacked disks were as much as 80 percent less than those measured for similar amplitude discharges through a solid metal rod. The energy dissipated per gap by arcing was calculated and found to increase as contact disk mass decreased. The i2dt action integral calculated for 3- to 12-kA discharges ranged from 53 A2s to 4210 A2s, respectively. The multiarc formation process is attributed to longitudinal electrodynamic forces separating the contact disks during current discharge.
CORRELATED X-RAY AND OPTICAL STREAK PHOTOGRAPHS OF EXPLODING WIRES,
Sequences of flash x-ray photographs of 70 nsec-duration obtained during the early expansion of copper, lead, and iron wires are correlated precisely in time with the electrical voltage pulse and optical streak photographs. Wire sizes were 10, 15, and 25 mil in diameter. The x-ray pictures show the onset and development of striations in each of these metals along the wire length during the fast resistance rise of the wire. The relatively smooth envelope of the radially expanding striations is compared with features of the optical streak pictures. Some of these optical pictures show a translucent radial cloud developing prior to the fast resistance rise, and a more opaque inner core which expands radially. Most of the striations in the x-ray pictures appear to be completely separated at the voltage maximum. After the voltage peak, the density of material appears to be greater further from the center. The observed behavior is discussed.
Resonant Auger decay study of C1s -> pi* core-excited OCS
The present work aims at characterizing short-lived C1s((-1)) pi*((1)) core-excited states of the OCS molecule based on the analysis of the vibrational fine structure and lineshape profiles of the high-resolution resonant Auger decay spectra recorded at the excitation energies along the C1s -> pi* resonance in the binding energy region 15-19eV. Very different behavior in terms of lineshape and resonant enhancement is observed for the (A) over tilde, (B) over tilde and (C) over tilde final states. This is explained by (1) the variation in the C-O bond lengths for the states involved in the electronic relaxation and (2) different contributions in terms of Mulliken population to the molecular orbitals determining the electronic character of the corresponding states. Since the final-state geometries are known from a number of previous experiments and ab initio calculations, the geometry of the C1s((-1)) pi*((1)) intermediate states can be predicted in analogy with e.g. the N-2, CO2 and N2O molecules. (C) 2009 Elsevier B.V. All rights reserved. (Less)