Study on Electron-Impact Excitation and Dielectronic Recombination of Atomic Ions by Crossed Beams Technique

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With the aim of developing a new technique to study the electron= impact excitation and ionization processes for atomic ions, we have set up the following experimental apparatus and measured several sets of ionization cross sections of atoms and atomic ions.1. We assembled a vacuum ultraviolet (VUV) emission spectrometer by installing a collision chamber on the entrance slit of a 50 cm Seya= Namioka VUV monochromator, and setting a position-sensitive-detector at its focal plane. We determined partial cross sections for ionization of the Ne-2s, Ar-3s, Kr-4s, and Xe-5s subshell electrons, by measuring VUV spectra using the spectrometer newly built. A part of the results has been published in references 1,3,4,8, and 9.2. In the aim to proceed the crossed-electron-ion beams technique, we developed a compact ion source for alkali and alkaline-earth ions of good efficiency. The ion source consists of a furnace, an annular nozzle, a heated Re ribbon where metal atoms are ionized, and an extraction electrode. It supplies an ion beam of 1 to 10 PA current intensity.3. By means of the crossed electron-ion beams technique, we have measured single ionization cross sections of O^+, S^+, S^<2+> (Ref.2), C^+, N^+, P^+ (Ref.5), F^+, Ne^+,Cl^+, Ar^+ (Ref.6), and Ne^<2+>, Ar^<2+>, Kr^<2+>, Xe^<2+> (Ref.7). In addition, we have measured the double and triple ionization cross sections of Ba^+, Sr^+, and Ca^+ as functions of impact energies (Ref.4,8).We are preparing the VUV spectroscopy of atomic ions by the crossed electron-ion beams technique.