Scaling of the energy confinement time with and collisionality approaching ITER conditions

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

The condition of the latest version of the ELMy H-mode database has been re-examined. It is shown that there is bias in the ordinary least squares regression for some of the variables. To address these shortcomings three different techniques are employed: (a)principal component regression, (b)an error in variables technique and (c)the selection of a better conditioned dataset with fewer variables. Scalings in terms of the dimensionless physics valiables, as well as the standard set of engineering variables, are derived. The new scalings give a very similar performance for existing scalings for ITER at the standard beta, but a much improvement performance at higher beta.