Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions

N. P. Basse, S. Zoletnik, P. K. Mlchelsen

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100 μs, similar to the lifetime observed during edge localized modes.

Original languageEnglish
Article number012507
Pages (from-to)1-11
Number of pages11
JournalPhysics of Plasmas
Volume12
Issue number1
DOIs
Publication statusPublished - 2005

Fingerprint

turbulence
controlled fusion
bursts
stellarators
plasma currents
electron energy
life (durability)
magnetic fields
ions
electrons

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Condensed Matter Physics

Cite this

Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions. / Basse, N. P.; Zoletnik, S.; Mlchelsen, P. K.

In: Physics of Plasmas, Vol. 12, No. 1, 012507, 2005, p. 1-11.

Research output: Contribution to journalArticle

@article{22da92463dea4008b701464f7ebb757e,
title = "Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions",
abstract = "Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100 μs, similar to the lifetime observed during edge localized modes.",
author = "Basse, {N. P.} and S. Zoletnik and Mlchelsen, {P. K.}",
year = "2005",
doi = "10.1063/1.1818142",
language = "English",
volume = "12",
pages = "1--11",
journal = "Physics of Plasmas",
issn = "1070-664X",
publisher = "American Institute of Physics Publising LLC",
number = "1",

}

TY - JOUR

T1 - Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions

AU - Basse, N. P.

AU - Zoletnik, S.

AU - Mlchelsen, P. K.

PY - 2005

Y1 - 2005

N2 - Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100 μs, similar to the lifetime observed during edge localized modes.

AB - Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100 μs, similar to the lifetime observed during edge localized modes.

UR - http://www.scopus.com/inward/record.url?scp=20444446708&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=20444446708&partnerID=8YFLogxK

U2 - 10.1063/1.1818142

DO - 10.1063/1.1818142

M3 - Article

VL - 12

SP - 1

EP - 11

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 1

M1 - 012507

ER -