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Journal Articles

Recent progress on the development and analysis of the ITPA global H-mode confinement database

McDonald, D. C.*; Cordey, J. G.*; Thomsen, K.*; Kardaun, O. J. W. F.*; Snipes, J. A.*; Greenwald, M.*; Sugiyama, L.*; Ryter, F.*; Kus, A.*; Stober, J.*; et al.

Nuclear Fusion, 47(3), p.147 - 174, 2007/03

 Times Cited Count:46 Percentile:29.82(Physics, Fluids & Plasmas)

This paper describes the updates to and analysis of the International Tokamak Physics Activity (ITPA) Global H-node Confinement Database version 3 (DB3) over the period 1994-2004. Global data, for the energy confinement time and its controlling parameters, have now been collected from 18 machines of different sizes and shapes: ASDEX, ASDEX Upgrade, C-Mod CoMPASS-D, DIII-D, JET, JFT-2M, JT-60U, MAST, NSTX, PBX-M, PDX, START, T-10, TCV, TdeV, TFTR and TUMAN-3M. A wide range of physics studies has been performed on DB3 with particular progress made in the separation of core and edge behavior, dimensionless parameter analyses and the comparison of the database with one-dimensional transport code. A key aim of the database has always been to provide a basis for estimating the energy confinement properties of next step machines such as ITER, and so the impact of the database and its analysis on such machines is also discussed.

Journal Articles

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.*; et al.

Plasma Physics and Controlled Fusion, 48(5A), p.A429 - A438, 2006/05

 Times Cited Count:15 Percentile:48.03(Physics, Fluids & Plasmas)

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.

Journal Articles

Scaling of the energy confinement time with $$beta$$ 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.*; et al.

Nuclear Fusion, 45(9), p.1078 - 1084, 2005/09

 Times Cited Count:51 Percentile:83.96(Physics, Fluids & Plasmas)

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.

Journal Articles

Overview of physics basis for ITER

Mukhovatov, V.*; Shimada, Michiya; Chudnovskiy, A. N.*; Costley, A. E.*; Gribov, Y.*; Federici, G.*; Kardaun, O. J. F.*; Kukushkin, A. S.*; Polevoi, A. R.*; Pustovitov, V. D.*; et al.

Plasma Physics and Controlled Fusion, 45(12), p.235 - 252, 2003/12

 Times Cited Count:48 Percentile:80.75(Physics, Fluids & Plasmas)

ITER will be the first magnetic confinement device with burning DT plasma and fusion power of about 0.5 GW. During the past few years, new results have been obtained that substantiate the confidence in achieving Q $$>$$ 10 in ITER with inductive H-mode operation. These include achievement of a good H-mode confinement near the Greenwald density at high triangularity of the plasma cross section; improvements in theory-based confinement projections for the core plasma; improvement in helium ash removal due to the elastic collisions of He atoms with D/T ions in the divertor predicted by modelling; demonstration of feedback control of NTMs and resultant improvement in the achievable beta-values; better understanding of ELM physics and development of ELM mitigation techniques; and demonstration of mitigation of plasma disruptions. ITER will have a flexibility to operate also in steady state and intermediate (hybrid) regimes. The paper concentrates on inductively driven plasma performance and discusses requirements for steady-state operation in ITER.

Journal Articles

Comparison of ITER performance predicted by semi-empirical and theory-based transport models

Mukhovatov, V.*; Shimomura, Yasuo; Polevoi, A. R.*; Shimada, Michiya; Sugihara, Masayoshi; Bateman, G.*; Cordey, J. G.*; Kardaun, O. J. F.*; Pereverzev, G. V.*; Voitsekhovich, I.*; et al.

Nuclear Fusion, 43(9), p.942 - 948, 2003/09

 Times Cited Count:41 Percentile:76.16(Physics, Fluids & Plasmas)

The values of Q = (fusion power)/(auxiliary heating power) predicted for ITER by three different methods are compared. The first method utilises an empirical confinement time scaling and prescribed radial profiles of transport coefficients, the second approach extrapolates from especially designed ITER similarity experiments, and the third approach is based on partly theory-based transport models. The energy confinement time given by the ITERH-98(y,2) scaling for an inductive scenario with plasma current of 15 MA and plasma density 15% below the Greenwald density is 3.7 s with one estimated technical standard deviation of 14%. This translates in the first approach into an interval for Q of [6-15] at the auxiliary heating power Paux = 40 MW and [6-30] at the minimum heating power satisfying a good confinement ELMy H-mode. Predictions of similarity experiments from JET and of theory-based transport models overlap with the prediction using the empirical confinement-time scaling within its estimated margin of uncertainty.

Journal Articles

ITER forecasts

Cordey, J. G.*; Takizuka, Tomonori; Miura, Yukitoshi; *; D.Boucher*; J.W.Connor*; Kardaun, O.*; Ryter, F.*; M.F.Turner*; A.Taroni*; et al.

Science, 275(5298), p.290 - 291, 1997/00

no abstracts in English

Journal Articles

ITER; Analysis of the H-mode confinement and threshold databases

Kardaun, O.*; Ryter, F.*; Stroth, U.*; Kus, A.*; Deboo, J. C.*; Schissel, D. P.*; Bramson, G.*; Carlstrom, T. N.*; Thomsen, K.*; Campbell, D. J.*; et al.

Plasma Physics and Controlled Nuclear Fusion Research 1992, Vol.3, p.251 - 270, 1993/00

no abstracts in English

Journal Articles

Global energy confinement H-mode database for ITER

Christiansen, J. P.*; Cordey, J. G.*; Thomsen, K.*; A.Tanga*; Deboo, J. C.*; Schissel, D. P.*; T.S.Taylor*; Kardaun, O.*; F.Wagner*; Ryter, F.*; et al.

Nuclear Fusion, 32(2), p.291 - 338, 1992/00

 Times Cited Count:71 Percentile:89(Physics, Fluids & Plasmas)

no abstracts in English

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