Rotation shear induced fluctuation decorrelation in a toroidal plasma

Technical Report · Wed Jun 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10160733· OSTI ID:10160733

Hahm, T S

The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

• Research Organization: Princeton Univ., NJ (United States). Plasma Physics Lab.
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 10160733
• Report Number(s): PPPL--2985; ON: DE94014034
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330
700370
BALLOONING INSTABILITY
CORRELATIONS
FLUCTUATIONS
NONLINEAR PROBLEMS
PLASMA FLUID AND MHD PROPERTIES
PLASMA KINETICS, TRANSPORT, AND IMPURITIES
SHEAR
TOKAMAK DEVICES