- 著者
- Katanuma I. Sato S. Okuyama Y. Kato S. Kubota R.
- 出版者
- American Institute of Physics
- 雑誌
- Physics of plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.20, no.11, pp.112107, 2013-11
A particle simulation of an interchange instability was performed by taking into account the ion finite Larmor radius (FLR) effects. It is found that the interchange instability with large FLR grows in two phases, that is, linearly growing phase and the nonlinear phase subsequent to the linear phase, where the instability grows exponentially in both phases. The linear growth rates observed in the simulation agree well with the theoretical calculation. The effects of FLR are usually taken in the fluid simulation through the gyroviscosity, the effects of which are verified in the particle simulation with large FLR regime. The gyroviscous cancellation phenomenon observed in the particle simulation causes the drifts in the direction of ion diamagnetic drifts.
- 著者
- Tsankov Tsanko V. Toko Kaoru Czarnetzki Uwe
- 出版者
- American Institute of Physics
- 雑誌
- Physics of plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.19, no.12, pp.123503, 2012-12
- 被引用文献数
- 13
A novel plasma source with a magnetic X-point has been developed to probe an alternative for cesium-free negative hydrogen ion production. This study presents first results for the gas and vibrational temperatures in the source at 1 Pa and various RF powers. The temperatures are obtained from analysis of the intensity distribution of the molecular Fulcher-α bands. The gas temperature increases with the RF power, while the vibrational temperature remains constant in the studied range of RF powers. Both quantities show no appreciable spatial dependence. The obtained high values of the vibrational temperatures indicate a high population of the vibrational levels, favourable for the volume negative ion production. A theoretical concept indicates the presence of an optimum value for the vibrational temperature at which the negative hydrogen ion yield by volume processes has a maximum. Coincidently, the measured value is close to this optimum. This indicates that the novel concept can provide certain advantages compared to other sources based on volume production.
- 著者
- Ito T. Katanuma I.
- 出版者
- American Institute of Physics
- 雑誌
- Physics of Plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.12, no.8, pp.082512, 2005-08-16
- 被引用文献数
- 5 4
The neoclassical resonant plateau transport in a mirror cell is studied theoretically. The analytical expression for a non-square-well magnetic field is obtained. The analytical result is applied to the GAMMA10 tandem mirror [T. Cho, M. Yoshida, J. Kohagura et al., Phys. Rev. Lett. 94, 085002-1 (2005)], which consists of several mirror cells in it, and the confinement time due to the neoclassical resonant plateau transport is determined in each mirror cell. It is found that the neoclassical resonant transport of ions trapped in the nonaxisymmetric anchor mirror cell and transition mirror cells is significantly smaller than those trapped in the central cell.
- 著者
- Sasagawa Y. Katanuma I. Mizoguchi Y. Cho T. Pastukhov V. P.
- 出版者
- American Institute of Physics
- 雑誌
- Physics of Plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.13, no.12, pp.122506, 2006-12-18
- 被引用文献数
- 9 9
Magnetohydrodynamic stabilization of an axisymmetric mirror plasma with a magnetic divertor is studied. An equation is found for the flute modes, which includes the stabilizing influence of ion temperature anisotropy and nonparaxial magnetic fields, as well as a finite ion Larmor radius. It is shown that if the density profile is sufficiently gentle, then the nonparaxial configuration can stabilize all modes as long as ion temperature is radially uniform. This can be demonstrated even when the density vanishes on the separatrix and even for small ion Larmor radii. It is found, however, that the ion temperature gradient makes the unstable region wider; high ion temperature is required to stabilize the flute mode.
- 著者
- Katanuma I. Yagi K. Nakashima Y. Ichimura M. Imai T.
- 出版者
- American Institute of Physics
- 雑誌
- Physics of Plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.17, no.3, pp.032303, 2010-03
- 被引用文献数
- 8 7
The computer code by reduced magnetohydrodynamic equations were made which can simulate the flute interchange modes (similar to the Rayleigh–Taylor instability) and the instability associated with the presence of nonuniform plasma flows (similar to the Kelvin–Helmholtz instability). This code is applied to a model divertor and the GAMMA10 [ M. Inutake et al., Phys. Rev. Lett. 55, 939 (1985) ] with divertor in order to investigate the flute modes in these divertor cells. The linear growth rate of the flute instability determined by the nonlocal linear analysis agrees with that in the linear phase of the simulations. There is a stable nonlinear steady state in both divertor cells, but the nonlinear steady state is different between the model divertor and the GAMMA10 with divertor.
- 著者
- Katanuma I. Yagi K. Haraguchi Y. Ichioka N. Masaki S. Ichimura M. Imai T.
- 出版者
- American Institute of Physics
- 雑誌
- Physics of plasmas (ISSN:1070664X)
- 巻号頁・発行日
- vol.17, no.11, pp.112506, 2010-11
- 被引用文献数
- 8 7
The flute instability and the associated radial transport are investigated in the tandem mirror with a divertor mirror cell (the GAMMA10 A-divertor) with help of computer simulation, where GAMMA10 is introduced [ Inutake et al., Phys. Rev. Lett. 55, 939 (1985) ]. The basic equations used in the simulation were derived on the assumption of an axisymmetric magnetic field. So the high plasma pressure in a nonaxisymmetric minimum-B anchor mirror cell, which is important for the flute mode stability, is taken into account by redefining the specific volume of a magnetic field line. It is found that the flute modes are stabilized by the minimum-B magnetic field even with a divertor mirror although its stabilizing effects are weaker than that without the divertor mirror. The flute instability enhances the radial transport by intermittently repeating the growing up and down of the Fourier amplitude of the flute instability in time.