Importance of the Rotational Transform for L-H Transitions in the TJ-II Stellarator Articles uri icon

authors

  • van Milligen, Boudewijn Philip
  • Estrada, Teresa
  • CARRERAS VERDAGUER, BENJAMIN A.
  • GARCIA GONZALO, LUIS

published in

publication date

  • June 2024

start page

  • 446

end page

  • 464

issue

  • 2

volume

  • 7

International Standard Serial Number (ISSN)

  • 2571-6182

abstract

  • We study the effect of the rotational transform profile on the L-H confinement transitions in the neutral beam-heated plasmas in the TJ-II stellarator. The rotational transform profile in the vacuum is determined by the external coil currents but is modified by the plasma current, (Formula presented.). We find that L-H confinement transitions systematically occur when the configuration and plasma current are such that a low-order rational is placed in the plasma edge region, with a distribution centered around (Formula presented.). It is suggested that magnetohydrodynamic turbulence plays an important role in triggering the L¿H transitions at TJ-II.

subjects

  • Physics

keywords

  • magnetic confinement; stellarator; turbulence; confinement transitions; rotational transform; rational surfaces