Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan 1)Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8580, Japan 2)Itoh Research Center for Plasma Turbulence, Kyushu University, Fukuoka 816-8580, Japan 3)Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 277-8561, Japan 4)National Institute for Fusion Science, Toki 509-5292, Japan (Received 7 December 2010 / Accepted 10 May 2011)