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Systematic investigation of electron impact excitation-autoionization from the groud state of highly charged GaI-like ions through. Delta. N=1 transitions

Conference ·
OSTI ID:6283465
;  [1];  [2]; ; ; ; ;  [3]
  1. Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev
  2. Lawrence Livermore National Lab., CA (USA)
  3. Hebrew Univ., Jerusalem (Israel). Racah Inst. of Physics

A systematic variation in the line intensity ratios of GaI-like and ZnI-like ions of rare earth elements has been recently observed in spectra emitted in a low density, high temperature tokamak plasma. This variation is shown to be correlated with the gradual opening of autoionizing channels through inner-shell excited configurations of the GaI-like charge-state. These channels enhance the indirect ionization rate of GaI-like ions through excitation-autoionization (EA), effecting the ionization balance and temperatures of greatest abundance. We present a systematic investigation of EA and direct impact ionization (DI) in the GaI-like isoelectronic sequence from Mo (Z = 42) to Dy (Z = 66). As Z decreases from Dy to Pr (Z = 59) the levels of the configuration 3d{sup 9}4p4f, which are excited from the ground state by strong dipole collisional transitions, gradually cross the first ionization limit of the ion and are responsible for this ionization enhancement. When Z decreases further an additional channel is opened through the configuration 3d{sup 9}4p4d. 9 refs., 3 figs., 1 tab.

Research Organization:
Lawrence Livermore National Lab., CA (USA)
Sponsoring Organization:
DOE/ER
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6283465
Report Number(s):
UCRL-JC-105958; CONF-9010298--3; ON: DE91007611
Country of Publication:
United States
Language:
English

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