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Giulietti, A.*; Andr
, A.*; Dobosz-Dufrnoy, S.*; Giulietti, D.*; 細貝 知直*; Koester, P.*; 小瀧 秀行; Labate, L.*; Levato, T.*; Nuter, R.*; et al.
Physics of Plasmas, 20(8), p.082307_1 - 082307_6, 2013/08
被引用回数：7 パーセンタイル：30.26(Physics, Fluids & Plasmas)A 65-fs, 800-nm, 2-TW laser pulse propagating through a Nitrogen gas jet has been experimentally studied by 90
Thomson scattering. Time-integrated spectra of scattered light show unprecedented broadening towards the blue which exceeds 300 nm. Images of the scattering region provide for the first time a space- and time-resolved description of the process leading quite regularly to such a large upshift. The mean shifting rate was as high as 
/fs, never observed before. Interferometry shows that it occurs after partial laser defocusing. Numerical simulations prove that such an upshift is consistent with a laser-gas late interaction, when laser intensity has decreased well below relativistic values (
) and ionization process involves most of the laser pulse. This kind of interaction makes spectral tuning of ultrashort intense laser pulses possible in a large spectral range.
Imbeaux, F.*; Citrin, J.*; Hobirk, J.*; Hogeweij, G. M. D.*; K
chl, F.*; Leonov, V. M.*; 宮本 斉児; 中村 幸治*; Parail, V.*; Pereverzev, G. V.*; et al.
Nuclear Fusion, 51(8), p.083026_1 - 083026_11, 2011/08
被引用回数：35 パーセンタイル：80.59(Physics, Fluids & Plasmas)In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from various tokamaks have been analysed by means of integrated modelling in view of determining relevant heat transport models for these operation phases. A set of empirical heat transport models for L-mode has been validated on a multi-machine experimental dataset for predicting the 
dynamics within 
0.15 accuracy during current ramp-up and ramp-down phases. The most accurate heat transport models are then applied to projections to ITER current ramp-up, focusing on the baseline inductive scenario (main heating plateau current of 
MA). These projections include a sensitivity study to various assumptions of the simulation. While the heat transport model is at the heart of such simulations, more comprehensive simulations are required to test all operational aspects of the current ramp-up and ramp-down phases of ITER scenarios. Recent examples of such simulations, involving coupled core transport codes, free-boundary equilibrium solvers and a poloidal field (PF) systems controller are also described, focusing on ITER current ramp-down.
Faenov, A. Y.; Magunov, A. I.*; Pikuz, T. A.*; Skobelev, I. Y.*; Giulietti, D.*; Betti, S.*; Galimberti, M.*; Gamucci, A.*; Giulietti, A.*; Gizzi, L. A.*; et al.
JETP Letters, 86(3), p.178 - 183, 2007/08
被引用回数：5 パーセンタイル：37.28(Physics, Multidisciplinary)X-ray spectroscopy diagnostics of laser-cluster interactions at a stage of non-adiabatical cluster expansion and formation of the spatially homogeneous plasma channel is carried out for the first time. It is shown, that X-ray line emission spectra of light elements, allows to determine parameters of the plasma formed at the time moment 10 ps from the beginning of femtosecond laser with relatively high plasma temperature Te 100 eV iand electron density Ne about 10
- 10
cm
.
神門 正城; Pirozhkov, A. S.; 林 由紀雄; 小瀧 秀行; Pikuz, T.; Faenov, A.*; Esirkepov, T. Z.; 中村 龍史*; Koga, J. K.; 大石 祐嗣*; et al.
no journal, ,
レーザープラズマ中で生成される大強度、非線形の航跡波は、光を一部反射する飛翔鏡として作用する。我々は、800nm, 400mJ, 30fsのレーザー光(ドライバー光)を用いてヘリウムガス中に飛翔鏡を作り、もう1つのレーザー光(ソース光)をこれに対向で入射させた。ソース光をプローブとして用いてアライメントする手法を新たに開発し、信号探索を行った結果、ドライバーの進行方向である0度、および13度方向の極端紫外光分光器にて準単色の信号を観測した。0度方向の計測では、粒子シミュレーションによる形状に近い構造であり、飛翔鏡の作用によるものと考えられる。13度方向での準単色構造は初めて計測されたものであり、飛翔鏡の一部から反射されたと考えられる。
神門 正城; Pirozhkov, A. S.; 林 由紀雄; 小瀧 秀行; Pikuz, T.; Faenov, A.*; Esirkepov, T. Z.; 大石 裕嗣*; Labate, L.*; Gizzi, L. A.*; et al.
no journal, ,
高強度・超短パルスレーザーをプラズマ中に照射することにより非線形プラズマ波を駆動する。この波は電子疎密波であり、電子が集群しそれらが一体となって亜光速で進むことから光を反射する飛翔鏡として作用する。この飛翔鏡の集光性能について調べるのが本研究の目的であり、今発表では準単色の極端紫外光領域の反射光を観測したので、そのスペクトルの結果と新たに開発したアライメント方法について報告する。
神門 正城; Pirozhkov, A. S.; 林 由紀雄; 小瀧 秀行; Pikuz, T.*; Faenov, A.*; Esirkepov, T. Z.; 大石 裕嗣*; Labate, L.*; Gizzi, L. A.*; et al.
no journal, ,
The relativistic flying mirror concept has several interesting features for generating short wavelength, coherent, ultrashort electromagnetic radiation. The experiment of the relativistic flying mirror was conducted in a head-on collision setup using J-KAREN laser (
400 mJ, 30 fs). Initially 800 nm laser pulses were converted to the extreme ultraviolet region (several tens of nm). The source size of the radiation was characterized to 7.1
m with an imaging system composed of a spherical mirror and CCD.
