Global confinement scaling for high-density plasmas in the Large Helical Device

J. Miyazawa, H. Yamada, S. Murakami, H. Funaba, Inagaki Shigeru, N. Ohyabu, A. Komori, O. Motojima

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Density and power scan experiments have been carried out at various magnetic field strengths on the Large Helical Device (LHD), to investigate the temperature and magnetic field dependences of the thermal diffusivity. In the moderate density regime, the thermal diffusivity shows gyro-Bohm-like parameter dependences. In the high-density and low-temperature regime, on the other hand, the thermal diffusivity increases with the square root of the local electron temperature and decreases with a 1.2 power of the magnetic field strength. The turning point temperature where the weak temperature dependence changes to the gyro-Bohm type is also found to increase with a 0.8 power of the magnetic field strength. Based on the experimental results, dimensionally correct scalings for the energy confinement time, τE, and the plasma stored energy for the high-density LHD plasmas have been derived. Compared with the gyro-Bohm model (τE ∝ (n/P)3/5, where n and P denote the density and the heating power, respectively) and the international stellarator scaling 1995 (τE ∝ n0.51P-0.59), our scaling has a weaker positive dependence on the density together with the mitigated power degradation as τE ∝ (n/P)1/3, owing to the weak temperature dependence of the thermal diffusivity.

Original languageEnglish
Pages (from-to)325-337
Number of pages13
JournalPlasma Physics and Controlled Fusion
Volume48
Issue number2
DOIs
Publication statusPublished - Feb 1 2006

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Plasma confinement
Plasma density
Thermal diffusivity
plasma density
thermal diffusivity
Magnetic fields
scaling
field strength
Plasma devices
magnetic fields
Temperature
Electron temperature
Density (specific gravity)
temperature dependence
Temperature distribution
stellarators
Plasmas
Heating
Degradation
temperature distribution

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Global confinement scaling for high-density plasmas in the Large Helical Device. / Miyazawa, J.; Yamada, H.; Murakami, S.; Funaba, H.; Shigeru, Inagaki; Ohyabu, N.; Komori, A.; Motojima, O.

In: Plasma Physics and Controlled Fusion, Vol. 48, No. 2, 01.02.2006, p. 325-337.

Research output: Contribution to journalArticle

Miyazawa, J, Yamada, H, Murakami, S, Funaba, H, Shigeru, I, Ohyabu, N, Komori, A & Motojima, O 2006, 'Global confinement scaling for high-density plasmas in the Large Helical Device', Plasma Physics and Controlled Fusion, vol. 48, no. 2, pp. 325-337. https://doi.org/10.1088/0741-3335/48/2/010
Miyazawa, J. ; Yamada, H. ; Murakami, S. ; Funaba, H. ; Shigeru, Inagaki ; Ohyabu, N. ; Komori, A. ; Motojima, O. / Global confinement scaling for high-density plasmas in the Large Helical Device. In: Plasma Physics and Controlled Fusion. 2006 ; Vol. 48, No. 2. pp. 325-337.
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