Polarization ofK-shell x-ray transitions ofTi19+andTi20

The importance of EBIT data for Z-pinch plasma diagnostics

“…the measured values of polarization obtained using the measured intensities (see Table 3) and a two-crystal technique from [30,35 ] along with theoretical predictions from [30] are listed for E b =4.8 keV. The ratio of intensities I 1 /I 2 from Table 3 close to 1 indicates almost equal values of polarizat ion of two lines.…”

“…They include the He-lik e lines, in particular the He α resonance line (w), the intercombination line IC (y), the forbidden lines x and z, and the inner-shell satellite lines of Li-like ions q a nd r. All th ese li nes are often used in the diagnostics of Ti plasmas from tokamaks [27,28] and electron beam ion traps [29]. In addition to these lines, the He-like resonance line Heβ, the H-like resonance line Lyα, the satellite line spectrometers with a Si (220) crystal, which records an alm ost pure parallel polarization state, and with a Si (110) crystal, which records a m ixture of both polarization states [ 30]. In the second experim ent the same technique was used, but the K-shell Ti spectra were generated by a quasi-Maxwellian electron beam [31].…”

Electron capture into few-electron heavy ions: Independent particle model

“…which implies the following choice of the effective charges: Z eff (Eu) = 62.0, Z eff (Au) = 78.1 and Z eff (U) = 91.1, respectively. By making use of these effective charges we are able to evaluate the statistical tensors A 20 (2p 3/2 ) and substitute them into equation (9) in order to obtain the alignment A 20 (1s 2p 3/2 J f = 1, 2) of the residual helium-like ions.…”

“…Below, therefore, we like to simplify this expression by making use of the IPM. That is, we first employ equation (9) to express the alignment parameters A 20 (1s 2p 3/2 J f = 1, 2) of the 1s 2p 3/2 J f = 1, 2 helium states in terms of the one-electron reduced tensors A 20 (2p 3/2 ):…”

“…A great number of case studies have therefore been performed in order to explore the angular and polarization properties of the subsequent decay and to derive the alignment of highly-charged ions, following the ion-atom (or ion-electron) collisions. For the electron-impact excitation of few-electron ions, for instance, these theoretical [5][6][7][8] and experimental [9][10][11][12] a e-mail: surz@mpi-hd.mpg.de studies had a strong impact upon the diagnostics of hightemperature laboratory and astrophysical plasmas as well as for probing relativistic effects in simple atomic systems. Much attention has been paid also onto the magnetic sublevel population of the ionic states as produced by the inner-shell (impact) ionization, for which detailed calculations have been performed both, within the nonrelativistic [2,13,14] as well as the relativistic distorted-wave theory [15,16].…”