Potential structure and transport in the magnetic island in LHD

K. Ida, S. Inagaki, M. Yoshinuma, N. Tamura, T. Morisaki

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Radial profiles of the space potential are measured at the n/m = 1/1 magnetic island produced by external perturbation coils in the Large Helical Device (LHD). Both the temperature and space potential are flat inside the magnetic island, and the large radial electric field shear appears at the boundary of the magnetic island because the radial electric field is zero inside the magnetic island. However, when the width of the magnetic island becomes large, the space potential profile becomes peaked because of the convective flow along the magnetic flux surface inside the magnetic island around the O point. The appearance of the convective flow suggests that the perpendicular viscosity is significantly reduced inside the magnetic island. The perturbation transport study using the cold-pulse propagation is a useful tool to study the transport inside the magnetic island, where the temperature gradient is zero in the steady state. Inside the magnetic island, the cold-pulse propagates slowly from the boundary toward the center, and radial profiles of the delay time are peaked at the magnetic island. The large delay time (slow pulse propagation) indicates that the thermal diffusivity is even small inside the magnetic island. These experimental results indicate that the heat and momentum transport are significantly improved inside the magnetic island although the temperature and flow gradients are zero due to the lack of heat and momentum fluxes.

Original languageEnglish
Pages (from-to)113-121
Number of pages9
JournalFusion Science and Technology
Volume58
Issue number1
DOIs
Publication statusPublished - Jan 1 2010

Fingerprint

magnetic islands
Time delay
Momentum
Electric fields
Thermal diffusivity
Magnetic flux
Thermal gradients
Viscosity
Fluxes
Temperature
convective flow
Hot Temperature
temperature gradients
time lag
profiles
pulses
momentum
perturbation
propagation
electric fields

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Potential structure and transport in the magnetic island in LHD. / Ida, K.; Inagaki, S.; Yoshinuma, M.; Tamura, N.; Morisaki, T.

In: Fusion Science and Technology, Vol. 58, No. 1, 01.01.2010, p. 113-121.

Research output: Contribution to journalArticle

Ida, K. ; Inagaki, S. ; Yoshinuma, M. ; Tamura, N. ; Morisaki, T. / Potential structure and transport in the magnetic island in LHD. In: Fusion Science and Technology. 2010 ; Vol. 58, No. 1. pp. 113-121.
@article{f8d6595ccc0c4ffea8ccba91a88ed409,
title = "Potential structure and transport in the magnetic island in LHD",
abstract = "Radial profiles of the space potential are measured at the n/m = 1/1 magnetic island produced by external perturbation coils in the Large Helical Device (LHD). Both the temperature and space potential are flat inside the magnetic island, and the large radial electric field shear appears at the boundary of the magnetic island because the radial electric field is zero inside the magnetic island. However, when the width of the magnetic island becomes large, the space potential profile becomes peaked because of the convective flow along the magnetic flux surface inside the magnetic island around the O point. The appearance of the convective flow suggests that the perpendicular viscosity is significantly reduced inside the magnetic island. The perturbation transport study using the cold-pulse propagation is a useful tool to study the transport inside the magnetic island, where the temperature gradient is zero in the steady state. Inside the magnetic island, the cold-pulse propagates slowly from the boundary toward the center, and radial profiles of the delay time are peaked at the magnetic island. The large delay time (slow pulse propagation) indicates that the thermal diffusivity is even small inside the magnetic island. These experimental results indicate that the heat and momentum transport are significantly improved inside the magnetic island although the temperature and flow gradients are zero due to the lack of heat and momentum fluxes.",
author = "K. Ida and S. Inagaki and M. Yoshinuma and N. Tamura and T. Morisaki",
year = "2010",
month = "1",
day = "1",
doi = "10.13182/FST10-A10798",
language = "English",
volume = "58",
pages = "113--121",
journal = "Fusion Science and Technology",
issn = "1536-1055",
publisher = "American Nuclear Society",
number = "1",

}

TY - JOUR

T1 - Potential structure and transport in the magnetic island in LHD

AU - Ida, K.

AU - Inagaki, S.

AU - Yoshinuma, M.

AU - Tamura, N.

AU - Morisaki, T.

PY - 2010/1/1

Y1 - 2010/1/1

N2 - Radial profiles of the space potential are measured at the n/m = 1/1 magnetic island produced by external perturbation coils in the Large Helical Device (LHD). Both the temperature and space potential are flat inside the magnetic island, and the large radial electric field shear appears at the boundary of the magnetic island because the radial electric field is zero inside the magnetic island. However, when the width of the magnetic island becomes large, the space potential profile becomes peaked because of the convective flow along the magnetic flux surface inside the magnetic island around the O point. The appearance of the convective flow suggests that the perpendicular viscosity is significantly reduced inside the magnetic island. The perturbation transport study using the cold-pulse propagation is a useful tool to study the transport inside the magnetic island, where the temperature gradient is zero in the steady state. Inside the magnetic island, the cold-pulse propagates slowly from the boundary toward the center, and radial profiles of the delay time are peaked at the magnetic island. The large delay time (slow pulse propagation) indicates that the thermal diffusivity is even small inside the magnetic island. These experimental results indicate that the heat and momentum transport are significantly improved inside the magnetic island although the temperature and flow gradients are zero due to the lack of heat and momentum fluxes.

AB - Radial profiles of the space potential are measured at the n/m = 1/1 magnetic island produced by external perturbation coils in the Large Helical Device (LHD). Both the temperature and space potential are flat inside the magnetic island, and the large radial electric field shear appears at the boundary of the magnetic island because the radial electric field is zero inside the magnetic island. However, when the width of the magnetic island becomes large, the space potential profile becomes peaked because of the convective flow along the magnetic flux surface inside the magnetic island around the O point. The appearance of the convective flow suggests that the perpendicular viscosity is significantly reduced inside the magnetic island. The perturbation transport study using the cold-pulse propagation is a useful tool to study the transport inside the magnetic island, where the temperature gradient is zero in the steady state. Inside the magnetic island, the cold-pulse propagates slowly from the boundary toward the center, and radial profiles of the delay time are peaked at the magnetic island. The large delay time (slow pulse propagation) indicates that the thermal diffusivity is even small inside the magnetic island. These experimental results indicate that the heat and momentum transport are significantly improved inside the magnetic island although the temperature and flow gradients are zero due to the lack of heat and momentum fluxes.

UR - http://www.scopus.com/inward/record.url?scp=77956665242&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77956665242&partnerID=8YFLogxK

U2 - 10.13182/FST10-A10798

DO - 10.13182/FST10-A10798

M3 - Article

AN - SCOPUS:77956665242

VL - 58

SP - 113

EP - 121

JO - Fusion Science and Technology

JF - Fusion Science and Technology

SN - 1536-1055

IS - 1

ER -