Thumbnail
Access Restriction
Open

Author Petty, C. C. ♦ Luce, T. C.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ TOKAMAK DEVICES ♦ SCALING LAWS ♦ PLASMA CONFINEMENT ♦ MAGNETIC CONFINEMENT ♦ THERMAL DIFFUSIVITY ♦ TRANSPORT THEORY ♦ BALLOONING INSTABILITY ♦ CHARGED-PARTICLE TRANSPORT
Abstract The scaling of heat transport with collisionality ({nu}) in the banana regime has been measured in both L-mode (low confinement) and H-mode (high confinement) plasmas on the DIII-D tokamak [Fusion Technol. {bold 8}, 441 (1985)] with the other dimensionless parameters held fixed. Understanding the collisionality scaling of heat transport helps to distinguish between the different proposed mechanisms of turbulent transport and allows the origin of power degradation and density scaling of confinement to be determined. For L-mode plasmas on DIII-D, the scaling of the effective (or one-fluid) thermal diffusivity with collisionality is close to zero at all radii, {chi}{sub eff}{proportional_to}{chi}{sub B}{nu}{sup {minus}0.08{plus_minus}0.10}, which is the expected scaling for the collisionless ion temperature gradient (ITG) and collisionless trapped electron modes. The ion and electron thermal diffusivities have the same collisionality scaling to within the experimental error. For H-mode plasmas, a stronger collisionality dependence of heat transport is observed, {chi}{sub eff}{proportional_to}{chi}{sub B}{nu}{sup 0.49{plus_minus}0.08} for a factor-of-8 scan in {nu}, which falls between the expected scalings of the collisionless ITG and collisionless trapped electron modes and that of the (edge) resistive ballooning mode. A portion of this H-mode collisionality scaling can be attributed to the {nu} dependence of neoclassical heat transport, especially in low collisionality regions of the plasma. {copyright} {ital 1999 American Institute of Physics.}
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 1999-03-01
Publisher Place United States
Journal Physics of Plasmas
Volume Number 6
Issue Number 3


Open content in new tab

   Open content in new tab