The causal relation between turbulent particle flux and density gradient Articles uri icon

authors

  • VAN MILLIGEN, B.PH.
  • CARRERAS, B.A.
  • GARCIA GONZALO, LUIS
  • MART├ŹN DE AGUILERA, A.
  • HIDALGO, C.
  • HERNANDEZ NICOLAU, JAVIER

publication date

  • July 2016

issue

  • 7

volume

  • 23

International Standard Serial Number (ISSN)

  • 1070-664X

Electronic International Standard Serial Number (EISSN)

  • 1089-7674

abstract

  • A technique for detecting the causal relationship between fluctuating signals is used to investigate the relation between flux and gradient in fusion plasmas. Both a resistive pressure gradient driven turbulence model and experimental Langmuir probe data from the TJ-II stellarator are studied. It is found that the maximum influence occurs at a finite time lag (non-instantaneous response) and that quasi-periodicities exist. Furthermore, the model results show very long range radial influences, extending over most of the investigated regions, possibly related to coupling effects associated with plasma self-organization. These results clearly show that transport in fusion plasmas is not local and instantaneous, as is sometimes assumed.

keywords

  • tj-ii stellarator; plasma boundary region; edge turbulence; transport; fluctuations; confinement; fusion; similarity; interplay; tokamak