Observations of spontaneous toroidal flow in the LHD

Yoshinuma, M.; Ida, K.; Yokoyama, M.; Nagaoka, K.; Osakabe, M.

doi:10.1088/0029-5515/49/7/075036

Cited by 23 publications

(19 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8 means an intrinsic rotation in the co-direction driven by ion temperature gradient. This observation is consistent with previous observation of intrinsic rotation without ion ITB discharges [37]. The qualitative evaluation of off-diagonal terms and diagonal term are required for further understanding of transport linkage among particles, momentum and heat, which is left for the future study.…”

Section: Effect Of Intrinsic Rotation Driven By Ion Temperature Gradientsupporting

confidence: 90%

Heat and momentum transport of ion internal transport barrier plasmas on the Large Helical Device

et al. 2011

Self Cite

View full text Add to dashboard Cite

The peaked ion-temperature profile with steep gradient so called ion internal transport barrier (ion ITB) was formed in the neutral beam heated plasmas on the Large Helical Device (LHD) and the high-iontemperature regime of helical plasmas has been significantly extended. The ion thermal diffusivity in the ion ITB plasma decreases down to the neoclassical transport level. The heavy ion beam probe (HIBP) observed the smooth potential profile with negative radial electric field (ion root) in the core region where the ion thermal diffusivity decreases significantly. The large toroidal rotation was also observed in the ion ITB core and the transport of toroidal momentum was analyzed qualitatively. The decrease of momentum diffusivity with ion temperature increase was observed in the ion ITB core. The toroidal rotation driven by ion temperature gradient so called intrinsic rotation is also identified.

show abstract

Section: Effect Of Intrinsic Rotation Driven By Ion Temperature Gradientsupporting

confidence: 90%

Heat and momentum transport of ion internal transport barrier plasmas on the Large Helical Device

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the open field region outside of the plasma boundary, flow in the counter-direction has been observed in both plasmas. These counter-flows with positive radial electric field seem to be consistent with the observations of radial electric field driven flow in the nested flux surface region in CHS 30 and LHD, 17 although the effects of the stochastic magnetic field should be taken into account. The opposite sign of toroidal flow shear between two plasmas shown in Fig.…”

Section: Flow Structure At the Edge Region With Stochastic Magnetisupporting

confidence: 86%

“…[11][12][13][14] There is an effect of flow damping in helical plasmas even in the toroidal direction caused by non-axisymmetry in toroidal direction, which is called the "parallel viscosity" and has been experimentally confirmed in the compact helical system (CHS) for the first time. 11,15 Spontaneous flows driven by radial electric field and ion temperature gradient were also observed where the parallel viscosity is relatively large, 16,17 and they are qualitatively consistent with neoclassical prediction. Recently, a large offset toroidal flow was observed with ion internal transport barrier (ion ITB) formation in the large helical device (LHD) and correlates with ion temperature gradient.…”

Section: Introductionsupporting

confidence: 73%

3-D effects on viscosity and generation of toroidal and poloidal flows in LHD

Nagaoka¹,

Ida²,

Yoshinuma³

et al. 2013

Physics of Plasmas

Self Cite

View full text Add to dashboard Cite

Three-dimensional effects on plasma flows have been experimentally studied in the large helical device with 3D configurations. Spontaneous toroidal flow without net driving force using the combination of perpendicular neutral beam injection (NBI) heating and balanced tangential NBI heating has been investigated with two magnetic configurations. Co-and counter-directed spontaneous flows have been observed depending on the collisionality. Toroidal flow shear changes the sign at 0:4 < r eff < 0:6 between co-and counter-flowing plasmas, where r eff is a averaged minor radius. The detailed flow structures have been also examined at the edge region with stochastic magnetic field.

show abstract

“…After the transition to the ITB phase, the intrinsic torque becomes positive and drives the plasma rotation in co-direction. This result is consistent with the disparity of toroidal rotation which is indicated by the significant contribution of spontaneous rotation in counter-direction in L-mode plasma [138] and co-direction in the ITB plasma [139] in LHD.…”

Section: Momentum Transport (Toroidal Flow Reversal)supporting

confidence: 89%

Bifurcation phenomena in magnetically confined toroidal plasmas

Ida

2020

Advances in Physics: X

Self Cite

View full text Add to dashboard Cite

Bifurcation phenomena observed in turbulence and transport, in topology of magnetic field and MHD, and the interplay between turbulence and MHD bifurcation in magnetically confined toroidal plasmas are reviewed. Two types of bifurcation phenomena in turbulent transport are discussed. One is significant change in the magnitude of the diffusion term and the other is a sign flip of non-diffusive term of transport. The bifurcation of diffusion term magnitude causes the transition to a so-called improved mode such as ion-electron root transition, L-mode to H-mode transition, and ITB formation. In contrast, the bifurcation of non-diffusion term sign causes the intrinsic flow reversal, convection reversal of bulk ion, and impurity ions. Two types of bifurcation phenomena in MHD are discussed. One is the bifurcation of static magnetic topology and the other is the bifurcation of MHD instability. The bifurcation of static magnetic topology is observed in between three magnetic topology (nested magnetic flux surface, magnetic island and stochastic magnetic field) in toroidal plasma. The bifurcation of MHD instability is observed as a parity change of MHD oscillation. The bifurcation of the magnetic island states caused by the interplay between turbulence and MHD is also discussed.

show abstract

Observations of spontaneous toroidal flow in the LHD

Cited by 23 publications

References 15 publications

Heat and momentum transport of ion internal transport barrier plasmas on the Large Helical Device

Heat and momentum transport of ion internal transport barrier plasmas on the Large Helical Device

3-D effects on viscosity and generation of toroidal and poloidal flows in LHD

Bifurcation phenomena in magnetically confined toroidal plasmas

Contact Info

Product

Resources

About