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論文

X-ray spectroscopy diagnoses of clusters surviving under prepulses of ultra-intense femtosecond laser pulse irradiation

Faenov, A. Ya.*; Skobelev, I. Yu.*; Pikuz, T.; Pikuz, S. A.*; Fortov, V. E.*; 福田 祐仁; 林 由紀雄; Pirozhkov, A. S.; 小瀧 秀行; 下村 拓也; et al.

Laser and Particle Beams, 30(3), p.481 - 488, 2012/09

 被引用回数:7 パーセンタイル:59.31(Physics, Applied)

It is shown that various spectroscopic methods based on measurements of X-ray spectra radiated from cluster targets can be used for estimation of the destruction degree of clusters by laser prepulses. These methods allow answering the important issue of preservation of the dense cluster core at the moment of the arrival of the main laser pulse. In addition, they can be used for quantitative estimation of the size of the undestroyed parts of the clusters and also for measuring the temperature and density of the preplasmas produced by the laser prepulses.

論文

The Spectra of the multicharged argon hollow ions; Observation, modeling and using for diagnostics of the early stage of the heating of clusters by a supper high contrast femtosecond laser pulses

Pikuz, T.; Faenov, A.*; Skobelev, I.*; Fortov, V. E.*; Boldarev, A.*; Gasilov, V.*; Chen, L. M.*; Zhang, L.*; Yan, W.*; Yuan, D.*; et al.

AIP Conference Proceedings 1465, p.181 - 201, 2012/07

 パーセンタイル:100

A study is made of the ultra-short laser pulse irradiation of Ar cluster targets. Experiments have been performed with large cluster sizes and using very high laser contrasts, which have allowed clear and unambiguous observation of exotic inner-shell transitions in near-neutral Ar ions. The interaction of the main laser pulse with the unperturbed target is a necessary requirement for observing these lines. Our measurements are supported by kinetics calculations in which a very detailed atomic model is used. X-ray spectral methods have been proposed to determine the parameters of the appearing plasma at the early stages of its evolution. It has been shown that the spectra of hollow ions are the most informative in the first moments of the heating of a cluster, whereas the diagnostics of the late stages can be performed using the conventional lines of multicharged ions.

論文

Observation and modeling of high resolution spectral features of the inner-shell X-ray emission produced by 10$$^{-10}$$ contrast femtosecond-pulse laser irradiation of argon clusters

Colgan, J.*; Abdallah, J. Jr.*; Faenov, A. Ya.*; Pikuz, T. A.*; Skobelev, I. Yu.*; 福田 祐仁; 林 由紀雄; Pirozhkov, A. S.; 川瀬 啓悟*; 下村 拓也; et al.

High Energy Density Physics, 7(2), p.77 - 83, 2011/06

 被引用回数:21 パーセンタイル:22.43(Physics, Fluids & Plasmas)

巨大アルゴンクラスターに超高コントラスト比の極短パルスレーザー照射した場合における、特異的な内殼X線発生について研究を行った。観測されたX線のほぼすべての特性は、非常に厳密な原子モデルを取り込んだキネティックモデル計算によって再現された。すなわち、ほぼ中性状態のアルゴン原子からHe様アルゴンイオンまでの多様なイオン化状態を含むプラズマからX線放射がなされたことを示唆している。ほぼ中性のアルゴン原子からのX線放射は、これまでの中程度のコントラスト比のレーザーを用いた実験では観測されておらず、今回の実験で用いたレーザーのコントラスト比が非常に高かったことを反映している。

論文

Mult-code ${{it ab initio}}$ calculation of ionization distributions and radiation losses for tungsten in tokamak plasmas

Ralchenko, Y.*; Abdallah, J. Jr.*; Bar-Shalom, A.*; Bauche, J.*; Bauche-Arnoult, C.*; Bowen, C.*; Busquet, M.*; Chung, H.-K.*; Colgan, J.*; Faussurier, G.*; et al.

AIP Conference Proceedings 1161, p.242 - 250, 2009/08

磁場閉じ込め核融合で用いられるタングステンプラズマにおけるイオン分布と放射損失の計算結果について述べる。シミュレーションは、nonLTEコード比較ワークショップの一環として行われたもので、各著者によって独立に開発した衝突輻射モデルの相互比較を行った。コード間で全体的に良い一致が見られたが、温度2$$sim$$3keVの低温の条件において、実験結果と顕著な違いが認められた。

論文

Modeling energy dependence of the inner-shell X-ray emission produced by femtosecond-pulse laser irradiation of xenon clusters

Berkelbach, T.*; Colgan, J.*; Abdallah, J. Jr.*; Faenov, A. Y.; Pikuz, T.*; 福田 祐仁; 山川 考一

Physical Review E, 79(1), p.016407_1 - 016407_6, 2009/01

 被引用回数:10 パーセンタイル:40.23(Physics, Fluids & Plasmas)

We employ the suite of atomic physics codes to model the inner-shell X-ray emission spectrum of xenon clusters and compare results with those obtained via observation by high-resolution X-ray spectroscopy the emission of Xe clusters irradiated by 30 fs laser pulses. We find that the commonly employed configuration average approximation breaks down and significant spin-orbit splitting necessitates a detailed level accounting. Additionally, were produce an interesting spectral trend for a series of experimental spectra taken with varyingpulse laser energy for fixed pulse duration.

論文

MUTA calculations of a laser-produced Mg hollow atom spectrum

Colgan, J.*; Abdallah, J. Jr.*; Faenov, A. Y.; Pikuz, T. A.*; Skobelev, I. Yu.*

Physica Scripta, 78(1), p.015302_1 - 015302_6, 2008/07

 被引用回数:10 パーセンタイル:39.99(Physics, Multidisciplinary)

A study is made of the spectra produced from a short-wavelengths long-pulse (nanosecond) laser incident on an Mg plasma. A very complex experimental spectrum is analyzed in detail by comparison with large-scale atomic kinetics calculations using mixed-UTA (MUTA) model.

口頭

Inner-shell X-ray emission from high contrast femtosecond-pulse laser irradiation of Ar clusters; Observation and modeling

Colgan, J.*; Abdallah, J. Jr.*; Faenov, A.*; Pikuz, T.; Skobelev, I.*; 福田 祐仁; 林 由紀雄; Pirozhkov, A. S.; 川瀬 啓悟*; 桐山 博光; et al.

no journal, , 

A study is made of the ultra short laser pulse irradiation of Ar cluster targets. Experiments have been performed with large cluster sizes and using very high laser contrasts, which have allowed clear and unambiguous observation of exotic inner shell transitions in near neutral Ar ions, so called hollow atom transitions. The interaction of the main laser pulse with the unperturbed target is a necessary requirement for observing these lines. Our measurements are supported by kinetics calculations in which a very detailed atomic model is used. The Los Alamos suite of atomic structure and kinetics codes is used to perform the modeling. The calculations predict all of the spectral features found experimentally, and support the notion that the X-ray emission arises from many ion stages of the Ar plasma, from near neutral through He like ions, and from a range of plasma temperatures and densities.

口頭

High-resolution X-ray spectroscopy diagnostics of early heating stage of clusters by high contrast femtosecond laser pulse

Faenov, A.*; Pikuz, T.; Skobelev, I.*; Fortov, V.*; Colgan, J.*; Abdallah, J. Jr.*; 福田 祐仁; 林 由紀雄; Pirozhkov, A. S.; 川瀬 啓悟*; et al.

no journal, , 

A study is made of the ultra-short laser pulse irradiation of Ar and CO$$_{2}$$ cluster targets. Experiments have been performed with large cluster sizes and using a variety of laser pulse durations and laser contrasts. Using very high laser contrasts of the J-KAREN laser facility allowed carrying out clear and unambiguous observation of exotic hollow ions of Ar and inner-shell transitions in near-neutral Ar ions and used them for diagnostics of early heating stage. Observation of asymmetric shapes of spectral lines of Oxygen ions also allowed to do diagnstics of early heating stage of custers irradiated by high contrast ultra-intense fs laser pulses.

口頭

Hollow-atom Al X-ray spectra excited by PW laser pulses in foil and CH-buried targets

Pikuz, S. Jr.*; Wagenaars, E.*; Culfa, O.*; Dance, R.*; Rossall, A.*; Tallents, G.*; Faenov, A.*; K$"a$mpfer, T.*; Schulze, K.*; Uschmann, I.*; et al.

no journal, , 

Aluminum K-shell spectra from solid targets were measured during an experiment at Vulcan Petawatt facility. Laser pulses of very high contrast and 150 J of energy allowed interaction studies between the very high intensive laser field and solid state. Intense emission of exotic spectral lines related to the transitions in Al hollow atoms were observed from Al targets. Specifically for 1.5 micron thin foil target the hollow atom yield dominated the resonance line emission. It is suggested that the hollow atoms were predominantly excited by the impact of keV X-ray photons generated on the front surface of the target. On the contrary, the spectra of aluminum foils buried in several microns of CH demonstrated lower K-shell emission and contained much weaker yield of hollow-atom lines. In this case the laser did not interact directly with aluminum matter, so most probably hollow atoms excited by fast electrons penetrating the target.

口頭

Radiation properties of dense matter pumped by X-ray emission of plasma irradiated by laser intensities over 10$$^{20}$$ W/cm$$^{2}$$

Faenov, A.*; Colgan, J.*; Abdallah, J. Jr.*; Pikuz, S. A.*; Wagenaars, E.*; Booth, N.*; Brown, C. R. D.*; Culfa, O.*; Dance, R.*; Evans, R.*; et al.

no journal, , 

It was demonstrated that Hollow ions exotic states of matter, which are very far from equilibrium, can be formed by conventional optical laser technology when the laser intensity reached 10$$^{20}$$ W/cm$$^{2}$$ and approaches to the radiation dominant regime.

口頭

Radiation properties of plasma irradiated by ultra-short laser pulses with intensities of 10$$^{21}$$ W/cm$$^{2}$$

Faenov, A.*; Hansen, S.*; Colgan, J.*; Abdallah, J.*; Pikuz, T.; Pikuz, S.*; Skobelev, I.*; 西内 満美子; 榊 泰直; 前田 祥太; et al.

no journal, , 

K-shell spectra of Al and Fe were excited by irradiation of thin foils with 30 fs laser pulses of J-KAREN laser facility with intensities up to 10$$^{21}$$ W/cm$$^{2}$$. Different dependences of measured spectra from the laser energy, different thicknesses of foils were investigated. Two independent models are used to provide a detail theoretical study of the role of the various configurations and processes in the formation of the observed spectra.

口頭

High resolution X-ray spectroscopy of plasma irradiated by ultra-short laser pulses with intensities of 10$$^{21}$$ W/cm$$^{2}$$

Faenov, A.*; Hansen, S. B.*; Colgan, J.*; Abdallah, J.*; Pikuz, T.; Pikuz, S. A.*; Skobelev, I. Y.*; 西内 満美子; 榊 泰直; 前田 祥太; et al.

no journal, , 

We present new set of measurements of high spectrally resolved K-shell spectra of Al and Fe plasma obtained by thin foils irradiation using 40 fs laser pulses of J-KAREN laser facility with intensities up to 10$$^{21}$$ W/cm$$^{2}$$. Dependences of X-ray spectra from laser energy and thicknesses of foils were investigated. Measured power-law dependence of X-ray intensity vs laser beam intensity confirmed that at laser intensities higher than 10$$^{20}$$ W/cm$$^{2}$$ Radiation Dominated regime could be reached. Two independent models are used to provide a detail theoretical study of the various configurations and processes roles in the formation of the observed spectra. Modeling demonstrated strong influence of X-ray photo pumping from laser-produced plasma for intensity and structure of observed X-ray spectra.

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