Spectroscopic characterization of ultrashort laser driven targets incorporating both Boltzmann and particle-in-cell models

Sherrill, M. E.*; Abdallah, J.*; Csanak, G.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.

High-Power Laser Ablation VII (Proceedings of SPIE Vol.7005), p.70051R_1 - 70051R_11, 2008/06

Spectroscopic characterization of an ultrashort-pulse-laser-driven Ar cluster target incorporating both Boltzmann and particle-in-cell models

Sherrill, M. E.*; Abdallah, J. Jr.*; Csanak, G.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.

Physical Review E, 73(6), p.066404_1 - 066404_6, 2006/06

https://doi.org/10.1103/PhysRevE.73.066404

A model that solves simultaneously both the electron and atomic kinetics was used to generate synthetic He X-ray spectra to characterize a high intensity ultrashort laser driven Ar cluster target experiment. In particular, level populations were obtained from a detailed collisional-radiative model where collisional rates were computed from a time varying electron distribution function obtained from the solution of the zero dimensional Boltzmann equation. In addition, aparticle-in-cell simulation was used to model the laser interaction with the cluster target and provided the initial electron energy distribution function (EEDF) for the Boltzmann solver. This study suggests that the high density plasma contribution to the time-integrated He spectrum was in a highly non-equilibrium state in both the EEDF and the ion level populations and provides a prediction of 5.7 ps for the average cluster integrity time for this high density state.

Measurement of ' X-ray transitions from 1 m Kr clusters irradiated by high-intensity femtosecond laser pulses

Hansen, S. B.*; Fournier, K. B.*; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; Skobelev, I. Y.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; et al.

Physical Review E, 71(1), p.016408_1 - 016408_9, 2005/01

https://doi.org/10.1103/PhysRevE.71.016408

X-ray line emission from ' transitions in Ne-like Kr and nearby ions has been observed from 1 m Kr clusters irradiated by fs-scale laser pulses at the JAERI facility in Kyoto, Japan. The dependence of 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. A collisional-radiative model based on the relativistic multiconfigured FAC code has been constructed and used to determine that the cluster plasma has electron densities near 10 cm, temperature of a few hundred eV and hot electron fraction of a few percent.

CORE PERFORMANCE TESTS AT LOW POWER FOR THE JOYO UPGRADE TO MK-III

Aoyama, Takafumi; Robert, W. S.; Maeda, Shigetaka; Sekine, Takashi

12th International Conference on Nuclear Engineeri, 0 Pages, 2004/00

Many changes were made in the recent upgrade of the JOYO experimental fast reactor to the MK-III design. Among the core changes made to achieve a four fold increase in irradiation capacity are the introduction of a second enrichment zone, an increase in core radius and a smaller decrease in core height. Performance tests done at low power, which focus on the neutronics characteristics, are presented. These tests include nuclear instrumentation system response, the approach to critical and excess reactivity, control rod calibrations performed several ways, and isothermal temperature coefficient evaluation. The measurements are emphasized but comparisons with calculated predictions are included. The design predictions are consistent with the performance test results, and all technical safety specifications are satisfied. The JOYO MK-III core will provide enhanced irradiation testing capability, as well as serving as a test bed for improving fast reactor operations, performance and

IAEA'97 expedition to the NW Pacific Ocean; Results of oceanographic and radionuclide investigations of the water column

Povinec, P. P.*; Livingston, H. D.*; Shima, Shigeki*; Aoyama, Michio*; Gastaud, J.*; Goroncy, I.*; Hirose, Katsumi*; Huynh-Ngoc, L.*; Ikeuchi, Yoshihiro*; Ito, Toshimichi; et al.

Deep Sea Research Part 2: Topical Studies in Oceanography, 50(17-21), p.2607 - 2637, 2003/09

https://doi.org/10.1016/S0967-0645(03)00138-3

An international sampling cruise, IAEA'97, was carried out in 1997 in the NW Pacif1c Ocean. The main results of this study are following: (1) The levels of oceanographic parameter showed differences from the historical data, (2) Transuranics water profiles showed typical sub-surface concentration maxima with decrease in concentration by about a factor of 4 from the historical results, deepening their positions by about a factor of 2 and declining the water column inventory by about 20% over 24 years, (3) Sr-90 and Cs-137 data confirmed that the observed changes in concentration profiles have been resulting from the regional water masses circulation, and (4) The concentrations of these radionuclides in surface water after 40 years of their main introduction to the NW Pacific are still showing a latitudinal dependence. The results present the most comprehensive recent study on the distribution of radionuclides in the NW Pacific Ocean with the implications for behaviour of these radionuclides in the water column and physical forcing of water mass circulation over the last 24 years.

None

Aoyama, S.*; Ishii, T.*; Horie, Y.*; Hokari, T.*; Horita, M.*

PNC TJ1060 92-002, 854 Pages, 1992/03

PNC-TJ1060-92-002.pdf:45.42MB

None

Novel mechanism of electron injection into acceleration regime during the high intense laser pulse interaction with clusters

Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Kiriyama, Hiromitsu; Yamakawa, Koichi; Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Masuda, Shinichi*; Echkina, E. Yu.*; et al.

no journal, , 

In this study, using a cluster jet containing micron-sized Ar clusters, we present for the first time experimental results and supporting calculations of the generation of collimated relativistic electrons up to 58 MeV accelerated during the interaction of a 23-fs laser pulse at a laser intensity of W/cm. The resulting spectrum does not fit a Maxwellian distribution, but is well described by a two-temperature Maxwellian. Two dimensional particle-in-cell simulations demonstrate that the lower energy electrons are accelerated by the wake field being injected during the plasma wave breaking. The high energy electrons are injected in the laser pulse interaction with the clusters, and then they gain their energy during the direct acceleration by the laser pulse.