Advanced spectroscopic analysis of 0.8—1.0-MA Moxpinches and the influence of plasma electron beams onL-shell spectra of Mo ions

Abstract

This paper presents a detailed investigation of the temporal, spatial, and spectroscopic properties of L-shell radiation from 0.8 to 1.0 MA Mo x pinches. Time-resolved measurements of x-ray radiation and both time-gated and time-integrated spectra and pinhole images are presented and analyzed. High-current x pinches are found to have complex spatial and temporal structures. A collisional-radiative kinetic model has been developed and used to interpret L-shell Mo spectra. The model includes the ground state of every ionization stage of Mo and detailed structure for the O-, F-, Ne-, Na-, and Mg-like ionization stages. Hot electron beams generated by current-carrying electrons in the x pinch are modeled by a non-Maxwellian electron distribution function and have significant influence on L-shell spectra. The results of 20 Mo x-pinch shots with wire diameters from 24 to 62 microm have been modeled. Overall, the modeled spectra fit the experimental spectra well and indicate for time-integrated spectra electron densities between 2 x 10(21) and 2 x 10(22) cm(-3), electron temperatures between 700 and 850 eV, and hot electron fractions between 3% and 7%. Time-gated spectra exhibit wide variations in temperature and density of plasma hot spots during the same discharge.

Effect of directional energetic electrons on the density diagnostic of hot plasmas

“…There have been numerous studies that have dealt with the influence of highly energetic electrons on the intensity of x-ray lines (see, e.g., [14,[18][19][20][21][22][23][24][25][26][27]). In most of these case studies, the energetic electrons were considered to be either isotropic or with a beam-like distribution, although in the latter case the effects of polarization and anisotropy of emission lines were not taken into account except for a few papers [14,21].…”

Source X quasi ponctuelle par X-pinch en régime sub-μs

“…Cependant, l'essentiel du rayonnement provient de la région du croisement, légèrement décalée vers l'anode. La structure des sources estétudiée par des sténopés de 10 m (la résolution spatiale, incluant le traitement d'image, Enfin, nous avons tenté avec succès de retrouver les raies spectrales mises enévidence sur d'autres expériences Z-pinch et X-pinch [3,4,7,8]. Les premiers résultats sont présentés figure 3.…”

Radiative properties of implosions of combined X-pinches and planar wire arrays composed from different wire materials on the UNR 1 MA Z-pinch generator

“…It was previously shown that the ratio of the Ne-like Mo lines (3A þ 3B)/(3F þ 3G) can be used as a reliable electron density N e diagnostic tool as it is not sensitive to the hot electrons and opacity in the range of the change of N e from 5 Â 10 19 to 5 Â 10 21 cm À3 [16,17]. Fig.…”

“…The Mo model was developed previously to diagnose experimental X-ray L-shell Mo spectra from 1MA UNR Zebra [16,17,10,12] and later was applied to the 470 kA Cornell XP X-pinches [17,18,11,12] as well as to the 20 MA SNL-Z wire arrays [7,8,17]. The Mg and Al models were developed to describe K-shell radiation from implosions from X-pinches and wire arrays with Al 5056 wires [13].…”