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Ishizawa, Akihiro*; Maeyama, Shinya; Watanabe, Tomohiko*; Sugama, Hideo*; Nakajima, Noriyoshi*
Journal of Plasma Physics, 81(2), p.435810203_1 - 435810203_41, 2015/04
Times Cited Count：32 Percentile：81.33(Physics, Fluids & Plasmas)Hirota, Makoto
Journal of Plasma Physics, 77(5), p.589 - 615, 2011/01
Times Cited Count：5 Percentile：23.28(Physics, Fluids & Plasmas)A new equation of motion that governs weakly nonlinear phenomena inideal magnetohydrodynamics (MHD) is derived as a natural extension of the well-known linearized equation of motion for the displacement field. This derivation is made possible by expanding the MHD Lagrangianexplicitly up to third order with respect to the displacement of plasma, which necessitates an efficient use of the Lie series expansion. The resultant equation of motion (i.e., the Euler-Lagrange equation) includes a new quadratic force term which is responsible for various mode-mode coupling due to the MHD nonlinearity. The third-order potential energy serves to quantify the coupling coefficient among resonant three modes and its cubic symmetry proves the Manley-Rower elations. In contrast to earlier works, the coupling coefficient is expressed only by the displacement vector field, which is already familiar in the linear MHD theory, and both the fixed and free boundary cases are treated systematically.
Sagisaka, Akito; Nagatomo, Hideo*; Daido, Hiroyuki; Pirozhkov, A. S.; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Nishiuchi, Mamiko; Yogo, Akifumi; Kado, Masataka
Journal of Plasma Physics, 75(5), p.609 - 617, 2009/06
Times Cited Count：5 Percentile：20.29(Physics, Fluids & Plasmas)We characterize the electron density distributions of preformed plasma for laser-accelerated proton generation. The preformed plasma of a thin-foil target is generated by prepulse and ASE of a high-intensity Ti:sapphire laser and is measured with an interferometer using a second harmonic probe beam. High-energy protons are obtained by reducing the size of the preformed plasma by changing the ASE duration before main pulse at the front side of the target. Simulation results with two-dimensional radiation hydrodynamic code are close to the experimental results for low-density region 
4
10
cm
at the front side.
Sagisaka, Akito; Utsumi, Takayuki*; Daido, Hiroyuki; Ogura, Koichi; Orimo, Satoshi; Takai, Mamiko; Hayashi, Yukio; Mori, Michiaki; Yogo, Akifumi; Kado, Masataka; et al.
Journal of Plasma Physics, 72(6), p.1281 - 1284, 2006/12
Times Cited Count：0 Percentile：0.01(Physics, Fluids & Plasmas)no abstracts in English
Tsuda, Takashi; Kurita, Genichi; Fujita, Takaaki
Journal of Plasma Physics, 72(6), p.1149 - 1152, 2006/12
Times Cited Count：3 Percentile：10.71(Physics, Fluids & Plasmas)The current density is expected to be negative in the central region of the tokamak when the amplitude of bootstrap current or off-axis current drive is large enough and a negative one-turn voltage exists. However, a flat current profile with almost zero value has been observed in experiments. The current profile with Current Hole has a tendency to be unstable to double tearing mode and we investigate the role of double tearing mode on the formation of Current Hole with RMHD simulation.
Koga, J. K.; Esirkepov, T. Z.; Bulanov, S. V.
Journal of Plasma Physics, 72(6), p.1315 - 1318, 2006/12
Times Cited Count：13 Percentile：41.68(Physics, Fluids & Plasmas)With the advent of high intensity short pulse lasers it has become possible to achieve extremely high intensities. When such laser pulses interact with high energy electron beams, radiation damping, which is usually small, can become large. We examine the effects of radiation damping on the backscattered Thomson radiation numerically and analytically. Using parameters comparable to the laser and microtron here at APRC we find that the overall spectrum is downshifted and that the overall amplitude of the radiation is smaller than in the case with no damping.
Miyato, Naoaki; Kishimoto, Yasuaki; Li, J.*
Journal of Plasma Physics, 72(6), p.821 - 824, 2006/12
Times Cited Count：0 Percentile：0.01(Physics, Fluids & Plasmas)Zonal flow behaviour and its effect on turbulent transport in reversed shear tokamaks are investigated by global nonlinear simulation of ion temperature gradient driven turbulence. When safety factor 
is reduced, zonal flows in a minimum region change from oscillatory ones to stationary ones and suppress the turbulent transport effectively. This result indicates that the change of zonal flow behaviour in the minimum region may trigger the formation of ion transport barriers.
Aiba, Nobuyuki; Tokuda, Shinji; Ishizawa, Tomoko*
Journal of Plasma Physics, 72(6), p.1127 - 1131, 2006/12
Times Cited Count：1 Percentile：3.54(Physics, Fluids & Plasmas)We develop the method for the stability analysis of a ideal external magnetohydrodynamic (MHD) mode by solving the eigenvalue problem associated with the two-dimensional Newcomb equation, the inertia free linear ideal MHD equation. This eigenvalue problem can be expected to provide a powerful tool for not only a low-n external MHD mode but also a high-n mode, where n is a toroidal mode number. With this method, we analyze an effect of the aspect ratio on the stability of middle-n (1
n10) external MHD modes in tokamaks; this gets attention for the design research of a high performance tokamak. As the result of this work, we study that external MHD modes become stable as the aspect ratio decreases, and also find that the stability of middle-n external modes becomes important because an effect of a conducting wall is enhanced by reducing the aspect ratio.
Ishii, Yasutomo; Azumi, Masafumi*; Smolyakov, A. I.*
Journal of Plasma Physics, 72(6), p.1243 - 1248, 2006/12
Times Cited Count：1 Percentile：3.54(Physics, Fluids & Plasmas)no abstracts in English
Matsumoto, Taro; Kishimoto, Yasuaki; Miyato, Naoaki; Li, J.*
Journal of Plasma Physics, 72(6), p.1183 - 1187, 2006/12
Times Cited Count：6 Percentile：21.49(Physics, Fluids & Plasmas)no abstracts in English
Li, J.*; Kishimoto, Yasuaki*; Miyato, Naoaki; Matsumoto, Taro; Dong, J. Q.*
Journal of Plasma Physics, 72(6), p.1173 - 1177, 2006/12
Times Cited Count：0 Percentile：0.01(Physics, Fluids & Plasmas)The dynamics of secondary fluctuations with poloidal long wavelength and low frequency in electron-temperature-gradient (ETG) turbulence saturation is considered in sheared slab geometry. A simplified modeling analysis shows that this kind of large-scale structure including streamers may saturate primary ETG instability through poloidal mode coupling. Spectral analyses in three-dimensional ETG simulations clearly exhibit the secondary excitation and the probable relevancy to ETG saturation. The result may implicate a lower fluctuation level in ETG turbulence.
Tomita, Yukihiro*; Smirnov, R.*; Takizuka, Tomonori; Tskhakaya, D.*
Journal of Plasma Physics, 72(6), p.1015 - 1018, 2006/12
Times Cited Count：2 Percentile：7.04(Physics, Fluids & Plasmas)The induced charge of a spherical conducting dust particle on a plasma-facing wall is studied analytically. An external non-uniform electric field is approximated by the polynomial of the axial coordinate and the bipolar coordinate is introduced in order to employ the boundary condition. The result is applied to the dust in the non-uniform electric field in the Debye sheath in front of the conducting wall. The results are useful for analyzing the shielding effects of the plasma surrounding a dust particle.
