Extreme ultraviolet emission lines of Ni xii in laboratory and solar spectra

Abstract

A B S T R A C TWavelengths for emission lines arising from 3s 2 3p 5 ±3s3p 6 and 3s 2 3p 5 ±3s 2 3p 4 3d transitions in Ni xii have been measured in extreme ultraviolet spectra of the Joint European Torus (JET) tokamak. The 3s 2 3p 5 2 P 1/2 ±3s 2 3p 4 ( 3 P)3d 2 D 3/2 line is found to lie at 152X90^0X02 AY a significant improvement over the previous experimental determination of 152X95^0X5 AX This new wavelength is in good agreement with a solar identification at 152X84^0X06 AY confirming the presence of this line in the solar spectrum. The Ni xii feature at 152.15 A Ê may be a result only of the 3s 2 3p 5 2 P 3/2 ±3s 2 3p 4 ( 3 P)3d 2 D 5/2 transition, rather than a blend of this line with 3s 2 3p 5 2 P 3/2 ±3s 2 3p 4 ( 3 P)3d 2 P 1/2 , as previously suggested. Unidentified emission lines at 295.32 and 317.61 A Ê in solar flare spectra from the Skylab mission are tentatively identified as the 3s 2 3p 5 2 P 3/2 ±3s3p 6 2 S 1/2 and 3s 2 3p 5 2 P 1/2 ±3s3p 6 2 S 1/2 transitions in Ni xii, which have laboratory wavelengths of 295.33 and 317.50 A Ê , respectively. Additional support for these identifications is provided by the line intensity ratio for the solar features, which shows good agreement between theory and observation.

Atomic data for astrophysics: Ni XII

“…Surprisingly, Sugar et al (1992) does not list this transition. Keenan et al (2000) reported observations with the Joint European Torus (JET) tokamak, and a wavelength of 152.90 Å for this line. However, we note that the profile of this line in the JET spectra looks asymmetric and the spectrometer used had a medium resolution of 0.2 Å.…”

“…These lines have similar intensities, and would be blended in most medium-resolution spectra, including the solar one of Malinovsky & Heroux (1973), and the JET tokamak (Keenan et al 2000;Mattioli et al 2004). We have re-measured the wavelength of the line observed in the Malinovsky & Heroux (1973) spectrum, obtaining a value of 152.80 ± 0.10 Å, i.e.…”

Spectroscopy of astrophysic al plasmas in the laboratory

“…This is illustrated in figures 1 and 2, where we show X‐ray spectra of helium‐like S xv (S 14+ ) from the Joint European Torus (JET) tokamak, and the Solar Maximum Mission (SMM) satellite, respectively (Harra‐Murnion et al 1996). For many years tokamak spectra have helped our understanding of solar observations, and vice‐versa, via for example line identifications at ultraviolet and X‐ray wavelengths (Harra‐Murnion et al 1996, Keenan et al 2000).…”