Weak turbulence theory of ion temperature gradient modes for inverted density plasmas

Technical Report · Fri Sep 01 04:00:00 EDT 1989

DOI:https://doi.org/10.2172/5705187· OSTI ID:5705187

Hahm, T S; Tang, W M

Typical profiles measured in H-mode ( high confinement'') discharges from tokamaks such as JET and DIII-D suggest that the ion temperature gradient instability threshold parameter {eta}{sub i} ({equivalent to}dlnT{sub i}/dlnn{sub i}) could be negative in many cases. Previous linear theoretical calculations have established the onset conditions for these negative {eta}{sub i}-modes and the fact that their growth rate is much smaller than their real frequency over a wide range of negative {eta}{sub i} values. This has motivated the present nonlinear weak turbulence analysis to assess the relevance of such instabilities for confinement in H-mode plasmas. The nonlinear eigenmode equation indicates that the 3-wave coupling to shorter wavelength modes is the dominant nonlinear saturation mechanism. It is found that both the saturation level for these fluctuations and the magnitude of the associated ion thermal diffusivity are considerably smaller than the strong turbulence mixing length type estimates for the more conventional positive-{eta}{sub i}-instabilities. 19 refs., 3 figs.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5705187
• Report Number(s): PPPL-2645; ON: DE90000874
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700103 -- Fusion Energy-- Plasma Research-- Kinetics
700107* -- Fusion Energy-- Plasma Research-- Instabilities
CLOSED PLASMA DEVICES
DIFFUSION
DOUBLET REACTORS
FLUCTUATIONS
INSTABILITY
ION TEMPERATURE
JET TOKAMAK
NONLINEAR PROBLEMS
PLASMA DENSITY
PLASMA INSTABILITY
TEMPERATURE DISTRIBUTION
TEMPERATURE GRADIENTS
THERMAL DIFFUSION
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTORS
TOKAMAK DEVICES
TOKAMAK TYPE REACTORS
TRANSPORT THEORY
TURBULENCE
VARIATIONS