B D Dudson et al 2005 Plasma Phys. Control. Fusion 47 885 doi:10.1088/0741-3335/47/6/010
B D Dudson1, R O Dendy2, A Kirk2, H Meyer2 and G F Counsell2
Show affiliationsEdge turbulence measurements from a reciprocating Langmuir probe in MAST are presented. A comparison of the range/standard deviation (R/S), growth of range, first moment and differencing and rescaling methods for calculating the Hurst exponent is made. The differencing and rescaling method is found to be the most useful for identifying scaling over long time-periods. A comparison is made between L-mode, dithering H-mode and H-mode plasma edge turbulence and evidence for self-similarity is found. Tests are performed and it is demonstrated that the results are due to properties of the data, and are not artefacts of the methods. A comparison of Hurst exponent methods with the autocorrelation function and power spectrum is used to demonstrate the presence of long-time correlation in L-mode data, and the absence of long-time correlation in the case of dithering H-mode.
Issue 6 (June 2005)
Received 7 January 2005, in final form 28 February 2005
Published 12 May 2005
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