K.-H. Schartner

Branching Ratios and Oscillator Strengths of Δn = 0 Transitions in the L-Shell of C I, N I, and O I Like Ions

Gas and foil excitation by and of ion beams from the 1 MV van de Graaff accelerator at Giessen and the 4 MV Dynamitron tandem accelerator at Bochum have been employed to induce Δn = 0 transitions in the L-shell of C I, N I and O I like ions of O, F, Ne and Si. Branching ratios have been measured and f-values have been determined using experimental lifetimes and the measured branching ratios. The results are compared with atomic structure calculations along isoelectronic series. Good overall agreement with the NCMET-formalism is found.

Experimental n=3 level lifetimes of Na-like heavy ions in the realm of massive relativistic effects

Abstract The lifetimes of the 3p 2 P° resonance levels and of the 3d 2 D levels in Na-like ions Xe 43+ ( Z = 54) and Au 68+ ( Z = 79) have been measured by time-resolved spectroscopy of foil-excited ion beams. This represents a major step beyond the previous data which reached only up to Z =29, into the range with massive relativistic effects. The results corroborate the lifetimes predicted by very recent calculations of the atomic structure which also reproduce the experimental transition wavelengths.

Time resolved EUV spectroscopy on foil-excited 5.9 MeV/u Xe and 13.2 MeV/u Au ions

N=3, Δn=0 transitions in Na-like ions have been observed and the resonance level lifetimes have been measured by time-resolved spectroscopy of foil-excited ion beams of Xe (Z=54) and Au (Z=79). Other lines in the same wavelength range are identified withn=3, Δn=0 transitions in Ne-, Mg-, and Al-like ions. Wavelengths and transition rates for these new lines are compared to the available theoretical data. A number of experimental problems are discussed.

Electron impact excitation and radiometric applications

Abstract The radiometric qualities of electron impact induced line radiation are discussed with emphasis on the spectral range of the vacuum ultraviolet. This is done in connection with a measurement of radiation losses from a fusion plasma, and with an investigation of electron impact induced double ionization of the Ar M shell. The excitation of He by highly charged ions is given as a third application. An appendix summarizes absolute cross sections for electron impact induced line emission, suited for a radiometric transfer standard.

Extreme-ultraviolet spectrum of Ne III

The spectrum of neon in the extreme-ultraviolet region has been studied in Penning discharge sources. New transitions are identified in the doubly ionized Ne iii spectrum below 250 A. Twenty multiplets of the 1s22s22p4–1s22s22p3nl transitions for n=3, 4, 5 have been classified, based on precise energy levels established in a recent study at higher wavelengths. Several new classifications in Ne ii are also suggested.

Measurement of the 2s2S12−2p2P32 wavelength in Li-like nickel

Abstract The wavelength of the 2s 2 S 1 2 −2p 2 P 3 2 transition in Li-like Ni was measured, using for the first time beam-foil spectroscopy. Ni13+ ions at 5.95 MeV/u and 11.68 MeV/u UNILAC-energies were excited by 200 μg/cm2 and 100 μg/cm2 carbon foils. A value of 16.5366 nm has been obtained with an accuracy of 0.0024 nm, corresponding to 1.8% of the QED contribution to the 2s–2p transition energy. The experimental procedure, based on an in situ wavelength calibration and a Doppler shift correction, is described. A comparison of the result with values from measurements at tokamaks and with calculations is carried out.

Beam‐foil studies of 2s ‐ 2p ‐ and of Rydberg ‐ transitions in He ‐ and Li‐like Kr

14.6 MeV/u Kr‐ions (Z=36) with charges between q=32 and q=36 were sent through carbon foils of 100 μg/cm2. He‐ and Li‐ like 2s‐2p transitions and Rydberg transitions between 5.5 nm and 13 nm were registered using a 5m grazing incidence spectrometer. Wavelengths of 11.102±0.008 nm and 9.099±0.008 nm were measured for the 2s 3S1‐2p 3P2 ‐ transition of Kr34+ and the 2s 2S1/2‐2p2P3/2‐transition of Kr33+. The dependence of the Rydberg line profile on the l‐level population was investigated. The data are compared with other experimental and theoretical results.

Excitation of He by highly charged fast projectiles

Abstract We have investigated excitation processes in He, induced in collisions with highly charged heavy ions. The projectile charge has been varied over a wide range from 6 1 − 45 at the specific energy of 1.4 MeV/u. The total excitation cross sections for optically forbidden transitions 1 1 S-n 1 S and n 1 D show qualitatively a ( q 2 -scaling behaviour, the optically allowed channels 1 1 S-n 1 P are overestimated by a q 2 -scaling.

Radiation losses from C and O plasma impurities in the spectral range of the VUV

Abstract Radiation losses in prominent C III and O VI lines emitted from ASDEX discharges have been measured. A normal incidence VUV spectrometer has been used which was calibrated with a radiometric standard based on electron impact induced line emission from gases. Furthermore C and O impurity concentrations were determined.

Experimental values of transition probabilities for 2s22p3-2s2p4 transitions along the N I like sequence☆

Transition probabilities for the 2s22p32D/2P-2s2p42P and 2s22p32D/2P-2s2p42D transitions in O II, F III, Ne IV and Si VIII ions have been determined. The results are compared with atomic structure calculations. A good overall agreement with data based on the NCMET method is observed which underlines the importance of electron correlations for the investigated decay processes