Empirical scaling laws for energy confinement in Ohmically-heated tokamaks

The interpretation and empirical determination of scaling laws for tokamak energy confinement are discussed. Special emphasis is given to the difficulty in determining the temperature dependence of the confinement time from Ohmically-heated data. A large collection of Ohmically-heated data is then presented. These data are analysed statistically to obtain the following temperature and confinement time scalings: Te=e−9.3ne−0.10a−1.29R0.66I0.88≡ Π and τEe = e−43.8ne0.90a0.98R1.63(Te/Π)γ. The exponent γ; is undetermined, and the units are mks and keV. If the confinement time is assumed independent of temperature and if dimensional constraints are imposed, then the best scaling becomes τEe = e−47.5 ne a5/4 R. These scalings are compared to several previously proposed ones.

[1]  N. Bretz,et al.  Aluminium limiter experiment in ST tokamak , 1976 .

[2]  Equipe Tfr.  Line radiation in the visible and in the ultraviolet in TFR tokamak plasmas , 1975 .

[3]  R. R. Parker,et al.  High-density discharges in the Alcator tokamak , 1977 .

[4]  B. Coppi,et al.  Anomalous transport model in high density regimes of confined plasmas , 1976 .

[5]  L. Spitzer,et al.  TRANSPORT PHENOMENA IN A COMPLETELY IONIZED GAS , 1953 .

[6]  L. C. Johnson,et al.  The ontogeny of a Tokamak discharge , 1973 .

[7]  P. Stott,et al.  Control of re-cycling and impurities in the ATC tokamak by means of gettered surfaces , 1975 .

[8]  C. Daughney,et al.  Empirical scaling for present Ohmically heated tokamaks , 1975 .

[9]  F. Hinton,et al.  Theory of plasma transport in toroidal confinement systems , 1976 .

[10]  J. W. Connor,et al.  Scaling laws for plasma confinement , 1977 .

[11]  S. Šesnić,et al.  High-density tokamak discharges in the pulsator device with βp > 1 , 1975 .

[12]  Equipe Tfr.  Electron temperature and Zeff measurements in the hot plasma of TFR by soft-X-ray analysis , 1977 .

[13]  N. Draper,et al.  Applied Regression Analysis , 1966 .

[14]  J. Sheffield,et al.  Empirical tokamak scaling , 1978 .

[15]  N. Bretz,et al.  Energy balance in a low-Z̄ high-density helium plasma in the ST Tokamak , 1975 .

[16]  S. Mirnov,et al.  Energy confinement time of a plasma as a function of the discharge parameters in Tokamak-3 , 1970 .

[17]  S. Gruber,et al.  Influence of the limiter material on the plasma characteristics in the Petula tokamak , 1976 .

[18]  D. R. Cohn,et al.  Reply to “Comments on the paper ‘Characteristics of high-density tokamak ignition reactors’” , 1976 .