The Role of aspect ratio and beta in H-mode confinement scalings

Kaye, S. M.*; Valovic, M.*; Chudnovskiy, A.*; Cordey, J. G.*; McDonald, D.*; Meakins, A.*; Thomsen, K.*; Akers, R.*; Bracco, G.*; Brickley, C.*; Bush, C.*; Cote, A.*; DeBoo, J. C.*; Greenwald, M.*; Hoang, G. T.*; Hogweij, D.*; Imbeaux, F.*; Kamada, Yutaka; Kardaun, O. J. W. F.*; Kus, A.*; Lebedev, S.*; Leonov, V.*; Lynch, S.*; Martin, Y.*; Miura, Yukitoshi; Ongena, J.*; Pacher, G.*; Petty, C. C.*; Romanelli, M.*; Ryter, F.*; Shinohara, Koji; Snipes, J.*; Stober, J.*; Takizuka, Tomonori; Tsuzuki, Kazuhiro*; Urano, Hajime

The effects of aspect ratio and beta on confinement scaling are studied with the use of the H-mode database extended by the low aspect ratio data from NSTX and MAST. Various statistical methods are applied. Development of scalings using engineering parameters as predictor variables results in the inverse-aspect-ratio scaling with the range from 0.38 to 1.29. The transformation of these scalings to physics variables results in an unfavorouble dependence of the normalized energy confinement time on beta. There is a strong correlation between the inverse aspect ratio and beta, and this makes scalings based on physics variables imprecise.