Muon spin rotation, relaxation, and resonance (SR) methods

Ito, Takashi; Shimomura, Koichiro*

Hydrogenomics; The Science of Fully Utilizing Hydrogen (Internet), p.43 - 49, 2023/03

Isotope-selective dissociation of diatomic molecules by terahertz optical pulses

Ichihara, Akira; Matsuoka, Leo*; Segawa, Etsuo*; Yokoyama, Keiichi

Physical Review A, 91(4), p.043404_1 - 043404_7, 2015/04

https://doi.org/10.1103/PhysRevA.91.043404

We propose a new method for isotope-selective dissociation of diatomic molecules in the gas phase by using two kinds of terahertz-pulse fields. The first field consists of a train of pulses, which composes a frequency comb, excites the selected isotope into highly-rotationally excited state. The second intense pulse field dissociates the excited molecule by further rotational excitations. We performed wave-packet computations using the lithium chlorides LiCL and LiCl to demonstrate the applicability of our method. Nearly 20% of LiCl in the lowest rovibrational state is dissociated in the designed pulse fields, while the dissociation probability is negligible in LiCl. This method is expected to be applicable to other diatomic molecules, and to molecular ensembles whose rotational states spread in energy.

Critical analyses with ferromagnetic and plasma rotation effects and wall geometry for a high steady state tokamak

Kurita, Genichi; Bialek, J.*; Tsuda, Takashi; Azumi, Masafumi*; Ishida, Shinichi; Navratil, G. A.*; Sakurai, Shinji; Tamai, Hiroshi; Matsukawa, Makoto; Ozeki, Takahisa; et al.

Nuclear Fusion, 46(2), p.383 - 390, 2006/02

https://doi.org/10.1088/0029-5515/46/2/020

It is shown that critical beta is decreased by ferromagnetic effect by about 8% for /2, and denoting the permeability of ferromagnetic wall and vacuum, respectively, for tokamak of aspect ratio 3. The existence of the stability window for resistive wall mode opened by both effects of the toroidal plasma rotation and the plasma dissipation, which was not observed for high aspect ratio tokamak, is found for tokamak of aspect ratio 3. The effect of ferromagnetism on them is also investigated. The critical beta analyses of NCT (National Centralized Tokamak) plasma using VALEN code are started with stabilizing plate and vacuum vessel geometry with finite resistivity, and the results for passive effect of stabilizing plate are obtained. The calculations including stabilizing effect of the vacuum-vessel and also active feedback control are also performed for present design of NCT plasma.

Mechanism of stabilization of ballooning modes by toroidal rotation shear in tokamaks

Furukawa, Masaru; Tokuda, Shinji

Physical Review Letters, 94(17), p.175001_1 - 175001_4, 2005/05

https://doi.org/10.1103/PhysRevLett.94.175001

A ballooning perturbation in a toroidally rotating tokamaks is expanded by square-integrable eigenfunctions of an eigenvalue problem associated with ballooning modes in a static plasma. Especially a weight function is chosen such that the eigenvalue problem has only the discrete spectrum. The eigenvalues evolve in time owing to toroidal rotation shear, resulting in countably infinite number of crossings among them. The crossings cause energy transfer from an unstable mode to the infinite number of stable modes; such transfer works as the stabilization mechanism of the ballooning mode.

Stability of ideal MHD ballooning modes and its stabilization by toroidal rotation shear near separatrix

Furukawa, Masaru; Tokuda, Shinji; Wakatani, Masahiro*

Plasma Physics and Controlled Fusion, 46(2), p.409 - 421, 2004/02

https://doi.org/10.1088/0741-3335/46/2/006

In the H-mode (high-confinement mode) pedestal region of a static or a toroidally rotating D-shaped tokamak plasma, the separatrix or the X-point affects the high-n ballooning stability (n: toroidal mode number) only in a thin layer in the pedestal region. Therefore, D-shaping effectively stabilizes the ballooning modes even for a toroidally rotating plasma with a separatrix.

A Model equation for ballooning modes in toroidally rotating tokamaks

Furukawa, Masaru; Tokuda, Shinji

Journal of Plasma and Fusion Research SERIES, Vol.6, p.210 - 213, 2004/00

A model equation for ballooning modes in toroidally rotating tokamaks is derived. It is confirmed that the model equation is appropriate for analyzing the stabilization mechanism of the ballooning modes by comparing the numerical solutions of the model equation with those of the original ballooning equations.

Transport threshold model of subsonic neoclassical tearing modes in tokamaks

Mikhailovskii, A. B.*; Shirokov, M. S.*; Tsypin, V. S.*; Konovalov, S. V.; Ozeki, Takahisa; Takizuka, Tomonori; Galvo, R. M. 0.*; Nascimento, I. C.*

Physics of Plasmas, 10(10), p.3975 - 3983, 2003/10

https://doi.org/10.1063/1.1604776

A transport threshold model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation. and to supply the parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport. It is shown that the subsonic NTMs transport threshold model can be more realistic than the standard transport threshold model of NTMs.

Separate structure of two branches of sheared slab mode and effects of plasma rotation shear in weak magnetic shear region

Li, J.; Kishimoto, Yasuaki; Tsuda, Takashi

Plasma Physics and Controlled Fusion, 42(4), p.443 - 453, 2000/04

https://doi.org/10.1088/0741-3335/42/4/306

no abstracts in English

Fast potential changes at H-mode transition in the JFT-2M tokamak

Hamada, Y.*; Ido, Tsuyoshi*; Kamiya, Kensaku*; *; Kawasumi, Y.*; Miura, Yukitoshi; JFT-2M Group

IAEA-CN-69/PDP/01 (CD-ROM), 4 Pages, 1999/00

no abstracts in English

Production of sheared flow during ion cyclotron resonance heating in tokamak plasmas

C.G.Liu*; Yamagiwa, Mitsuru; S.J.Qian*

Physics of Plasmas, 4(8), p.2788 - 2790, 1997/08

https://doi.org/10.1063/1.872446

no abstracts in English