title: Measurement of 2l-nl' x-ray transitions from approximately 1 microm Kr clusters irradiated by high-intensity femtosecond laser pulses.
abstract: X-ray line emission from 2l-nl' transitions in Ne-like Kr and nearby ions has been observed from approximately 1 microm Kr clusters irradiated by fs-scale laser pulses at the JAERI facility in Kyoto, Japan. The incident laser intensity reached 10(19) W/cm2, with pulse energies from 50 to 300 mJ and pulse durations from 30 to 500 fs. The dependence of the x-ray spectral features and intensity on the incident laser intensity is rather weak, indicating that the 1-2 ps cluster lifetimes limit the number of ions beyond Ne-like Kr that can be produced by collisional ionization. Lines from F- to Al-like Kr emitted from the cluster plasmas have been identified using data from the relativistic multiconfiguration flexible atomic code. A collisional-radiative model based on these data has been constructed and used to determine that the cluster plasma has electron densities near 10(22) cm(-3), temperatures of a few hundred eV, and hot electron fractions of a few percent.
authors.affiliation: Lawrence Livermore National Laboratory, P.O. Box 808, L-473, Livermore, California 94550, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Hansen
authors.forename: K B
authors.initials: KB
authors.lastname: Fournier
authors.forename: A Ya
authors.initials: AY
authors.lastname: Faenov
authors.forename: A I
authors.initials: AI
authors.lastname: Magunov
authors.forename: T A
authors.initials: TA
authors.lastname: Pikuz
authors.forename: I Yu
authors.initials: IY
authors.lastname: Skobelev
authors.forename: Y
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Y
authors.initials: Y
authors.lastname: Akahane
authors.forename: M
authors.initials: M
authors.lastname: Aoyama
authors.forename: N
authors.initials: N
authors.lastname: Inoue
authors.forename: H
authors.initials: H
authors.lastname: Ueda
authors.forename: K
authors.initials: K
authors.lastname: Yamakawa