X-ray generation in laser-heated cluster beams
- Institute of Molecular Physics, RRC 'Kurchatov Institute', 123182 Moscow (Russian Federation)
- Max-Born-Institut, 12489 Berlin (Germany)
Emission of x-rays by large clusters with 10{sup 8} to 10{sup 10} constituents irradiated by an intense laser pulse (10{sup 16} to 10{sup 18} Wcm{sup -2}) is analyzed. A self-consistent model for the cluster evolution during and after the irradiation is developed. The model takes into account absorption of radiation, formation of multicharged ions, and cluster expansion. The model is applied to relate the parameters of the cluster beam and the laser pulse to those of the forming plasma. It predicts that the plasma stays quasineutral and Maxwellian. We find that the expansion of large clusters goes through different stages after the end of the laser pulse and is not appropriately described by the Coulomb expansion model, which underestimates the cluster lifetime. For a more realistic description, the nonuniformity of the plasma must be considered. X-rays are generated in the interaction of the trapped electrons with the cluster ions. Two such radiative processes are considered in detail: dielectronic recombination and excitation of ions by electron impact followed by photon emission. Under the above conditions, the contributions of both processes to x-ray emission are comparable. To evaluate the x-ray spectrum a statistical description of the spectral lines is justified and applied. Knowing the rates that characterize the processes in the plasma, the main processes proceeding in the system can be identified. A simple calculation including several types of transitions is carried out.
- OSTI ID:
- 20852930
- Journal Information:
- Physical Review. A, Vol. 74, Issue 1; Other Information: DOI: 10.1103/PhysRevA.74.013201; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
07 ISOTOPES AND RADIATION SOURCES
ABSORPTION
ATOMIC CLUSTERS
CLUSTER BEAMS
CLUSTER EXPANSION
ELECTRON-MOLECULE COLLISIONS
EMISSION SPECTRA
EXCITATION
ION PAIRS
IRRADIATION
LIFETIME
MULTICHARGED IONS
PHOTON EMISSION
PHOTON-MOLECULE COLLISIONS
PLASMA
PLASMA PRODUCTION
PULSES
RECOMBINATION
TRAPPED ELECTRONS
X RADIATION
X-RAY SPECTRA