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Koga, J. K.; Bulanov, S. V.; Esirkepov, T. Z.; Pirozhkov, A. S.; 神門 正城; Rosanov, N. N.*
Europhysics Conference Abstracts (Internet), 36F, p.O5.214_1 - O5.214_4, 2012/00
Photon-photon scattering is a fundamental theoretical prediction of quantum electrodynamics. However, only an upper bounds on the cross section at photon energies of eV levels has been achieved. Since for low photon energies the scattering cross section increases as the sixth power of the photon energy, measuring photon-photon scattering at higher energies is advantageous. To generate these high energy photon beams we propose using laser pulses reflected and frequency up-shifted by mirrors moving at relativistic velocities. The reflected laser pulses due to the double Doppler effect can have high energy, extremely short duration, coherency and can be focused to very small spots. We present the scalings of the photon-photon scattering for each relativistic mirror configuration and show where photon-photon scattering in the keV photon energy range could be observed with current/near future and next generation laser systems.
本多 充; 福山 淳*; 中島 徳嘉*
Europhysics Conference Abstracts (Internet), 36F, p.P5.014_1 - P5.014_4, 2012/00
The one-dimensional multi-fluid transport code TASK/TX is used to investigate the physics regarding rotation, radial current and the radial electric field. Unlike conventional diffusive transport codes, its equation system is more fundamental in that the code directly solves the momentum equations for all species plus Maxwell's equations. The main drawback to the code is that the basis equations are built on the cylindrical coordinates. Neoclassical effects have already been incorporated and its validity has been confirmed, but any geometrical effects have not entered yet. In this study, we derive the equations on the axisymmetric flux coordinates in a manner consistent with the current TASK/TX concept. The equations are projected onto the radial, poloidal ant toroidal directions in the current framework. In the flux coordinates, however, we have to project the equations of motion onto the radial, parallel and toroidal direction because of the neoclassical nature of a toroidal plasma.
浦野 創; 滝塚 知典*; 菊池 満; 仲野 友英; 藤田 隆明; 林 伸彦; 大山 直幸; 鎌田 裕; JT-60チーム
Europhysics Conference Abstracts (Internet), 36F, p.P1.016_1 - P1.016_4, 2012/00
JT-60Uにおいて軽水素・重水素Hモードプラズマのエネルギー閉じ込め特性を調べた。重水素のエネルギー閉じ込め時間は軽水素のそれより約1.2-1.3倍長いことがわかった。プラズマ熱エネルギーを一定にした比較を行った場合、密度・温度分布が両者で一致したが、一方で軽水素時には高パワー入力を要した。そのときの軽水素のイオンの熱伝導流束は重水素時の約2倍であった。したがって、軽水素のイオン熱拡散係数も同様に約2倍に増加した。重水素のイオン温度勾配特性長は軽水素時と比較して約1.2倍程度短くなることを示した。
松永 剛; 神谷 健作; 篠原 孝司; 宮戸 直亮; 小島 有志; Bierwage, A.; JT-60チーム
Europhysics Conference Abstracts (Internet), 36F, p.P2.062_1 - P2.062_4, 2012/00
In the JT-60U experimental operations with high normalized beta 
or high bootstrap fraction 
, magnetic fluctuations with multiple peaks in the geodesic acoustic mode (GAM) frequency range are observed. These peaks appear just after tangential NB injection with 90 keV beam energy in L-mode phase to form weak/strong reversed magnetic shear plasmas. Observed magnetic fluctuations have 
= 0 axisymmetric toroidal mode structures and 
= 2 poloidal ones, where and are the toroidal and poloidal mode number, respectively. Interestingly, the poloidal mode structure sometimes behaves like standing wave. Usually, the standing wave nodes are located around the inboard and outboard midplanes, and the top and bottom of plasmas. Namely, these modes have = 2 components in both ion and electron diamagnetic directions. We will report the detail of the observed = 0 axisymmetric modes in the JT-60U tokamak.
Giruzzi, G.*; Artaud, J. F.*; Joffrin, E.*; Garcia, J.*; 井手 俊介; JT-60SA Research Plan Contributors; JT-60SAチーム
Europhysics Conference Abstracts (Internet), 36F, p.P5.018_1 - P5.018_4, 2012/00
Here, sets of simulations of the main JT-60SA operation scenarios performed with the 0.5-D code METIS will be presented and discussed. METIS computes the time evolution of the global plasma quantities for given waveforms of the control parameters. It solves the current diffusion equation taking into account an approximate equilibrium evolution. Simplified treatment of the sources and of spatial dependences allow simulation of a discharge in a CPU time of the order of one minute, while keeping account of all the main non-linearities of the evolution. This approach allows completing the 0-D analysis with radial profiles and time evolutions. Evaluation of scalar parameters of a few JT-60SA scenario such as the normalized beta by METIS is found to be close those evaluated by ACCOME.
Garcia, J.*; 林 伸彦; Giruzzi, G.*; Schneider, M.*; Joffrin, E.*; 井手 俊介; 坂本 宜照; 鈴木 隆博; 浦野 創; JT-60チーム; et al.
Europhysics Conference Abstracts (Internet), 36F, p.P5.057_1 - P5.057_4, 2012/00
Predictive simulations for electron and ion temperatures have been carried out for JET and JT-60U plasmas in order to determine the most appropriate models to this type of plasmas. To carry out this programme, the integrated modelling codes CRONOS and TOPICS-IB are used. Results show that the H-modes are usually well simulated for both devices, whereas for the advanced regimes, as the hybrid, there are clear deviations from experimental data, mainly for JT-60U. The reasons for such discrepancies are analysed.
相羽 信行; Cooper, W.*; Gruber, R.*
Europhysics Conference Abstracts (Internet), 36F, p.P2.045_1 - P2.045_4, 2012/00
線形MHD安定性を数値解析する際に問題となる数値不安定性の発生を抑えることに成功した新たな高精度数値解析手法を開発した。この数値不安定性の抑制に関する議論は30年ほど前に精力的に議論され、その不安定性を引き起こす要因についてはほぼ特定されていたが、本研究では同手法を用いた数値解析を行うとしばしば数値不安定性が発生してしまうことが確認された。この原因について解析的及び数値的に調べた結果、従来の解析手法で用いている数値積分法が不適切であるために数値不安定性を抑えきれていないことを明らかにした。この問題を解決するために、数値積分法を改善した新たな数値解析法を開発し、同手法を数値コードに実装して改めて解析を行った結果、数値不安定性を完全に抑制できることを確認した。また、プラズマ回転を考慮した場合でも、同様の数値解析手法により数値不安定性の発生は抑えられることを解析的に確認した。
瀬戸 慧大*; 長友 英夫*; Koga, J. K.; 三間 圀興*
no journal, ,
If the laser intensity is higher than 
W/cm
, strong bremsstrahlung might occur with a relativistic motion. Accompanying this, the "radiation reaction force" works on the charged particle. Therefore, it is necessary to study the radiation reaction effects in the ultra relativistic laser-electron interaction regime. We've considered the Lorentz-Abraham-Dirac (LAD) equation which can describe this phenomena, but it has mathematical difficulties. For solving this, there are many methods (the approximation of the radiation reaction force, new assumptions of the model). The LAD equation has been recently derived by the effective Lagrangian method in QED. This comes from the diagram of self-photon interaction. We will discuss about the meaning of the LAD equation and some other equations.
