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Abstract:
In the scrape-off layer of the Joint European Torus [P.-H. Rebut, R. J. Bickerton, and B. E. Keen, Nucl. Fusion 25, 1011 (1985)], Langmuir probes were used to measure the correlation of ion saturation current fluctuations parallel to the magnetic-field B. It was possible to realize three different probe tip separations (connection lengths) parallel toB under almost identical plasma conditions and magnetic configuration. Among these, a probe tip separation of 66 m parallel toB represents the largest value ever realized for this type of experiment. It was found that the correlation is reduced from greater than or equal to80% at 0.75 m probe tip separation parallel toB in the divertor to approximate to40% at 23 m, but remains at approximate to40% even for the 66 m separation. An upper limit for the ratio between the average wave numbers parallel and perpendicular to the magnetic field parallel to(k) over bar (parallel to)/(k) over bar (perpendicular to)parallel to<0.0022 is found, but the results are in good agreement with a parallel wave number (k) over bar (parallel to)=0. (C) 2002 American Institute of Physics.
