Electron cyclotron resonance ion source developments at Louvain-la-Neuve

Absolute cross sections for electron impact ionization of multiply charged argon ions (Arq+) have been measured in an animated crossed electron–ion beam experiment. Results are reported for single ionization (SI) (q = 4–6, 8, 10 and 11) ions and for double ionization (DI) (q = 5–11). The measurements cover the energy range from threshold to about 6000 eV. The direct process is seen to dominate SI for q = 8, 10 and 11. For charge states 4–6, excitation–autoionization processes are seen to largely contribute to the ionization signal. In addition, metastable states are unambiguously identified for Ar5+ and Ar6 +. Ionization–autoionization (IA) from the L shell accounts predominantly for DI of Arq+ (q = 5, 6). For charge states 7–11 direct DI is found to decrease strongly with respect to IA from the K shell.

Section: Methods and Apparatusmentioning

confidence: 99%

Electron impact ionization of argon ions (q 4 11)

Zhang¹,

Cherkani-Hassani²,

Belenger³

et al. 2002

“…The device is shown schematically in figure 1. The krypton ion beam is extracted from an electron cyclotron resonance (ECR) ion source (1), designed to produce ions from gas or metals by using the sputtering method (Barué et al 1998). Ion beams are accelerated by a voltage of 10 kV, mass-analysed (2), focused and deflected to the collision region by a vertical lens (3) and by two cylindrical deflectors (4), ( 5).…”

Section: Methods and Apparatusmentioning

confidence: 99%

Electron-impact single ionization of krypton ions (q= 12-18)

Khouilid

Cherkani-Hassani

Rachafi

et al. 2001

Absolute cross sections for electron-impact single ionization of krypton ions Krq + (q = 12-18) have been measured. The animated crossed-beam method has been applied. The measurements cover the energy range from threshold to about 5.5 keV. The presence of ions formed in metastable states is observed for Kr18+, Kr16+ and Kr14+. Inner-shell excitation from the 2s, 2p, 3s and 3p subshells followed by autoionization is seen to play a dominant role for this reaction over the whole energy range. The importance of these excitation-autoionization processes explains the large underestimation of cross sections from the available theoretical and semi-empirical estimations which include direct processes only.

“…The apparatus was essentially described earlier (Duponchelle et al 1995). Krypton ions are extracted from an ECR source (Barué et al 1998). Ions are accelerated by a voltage of 10 kV, mass analysed and focused onto the collision region.…”

Section: Methods and Apparatusmentioning

confidence: 99%

Electron impact double ionization of krypton ions (q= 14-17)

Khouilid

Cherkani-Hassani

Adimi

et al. 2001

Absolute cross sections for electron impact double ionization of krypton ions Krq + (q = 14-17) have been measured from threshold to 5 keV. The animated crossed beam method has been employed. Direct double ionization is seen to reduce strongly along the isonuclear sequence. Ionization-autoionization from the inner L-shell is seen to be the dominant process. It is roughly approximated by the semi-empirical Lotz formula assuming total autoionization of the ionic intermediate states. Resonant capture and excitation processes implying the L-shell are also obtained for charge states 14-16.