Isotope scaling and {eta}{sub i} mode with impurities in tokamak plasmas [report]

J.Q. Dong, W. Horton, W.D. Dorland
1994 unpublished
The ion temperature gradient driven instability, or r_ mode, is studied for discharges with hydrogen, deuterium or tritium in a toroidal magnetic configuration. Impurity effects on the mode and the instability which is driven by the presence of impurity ions (impurity modes) are studied as well. It is found that the maximum growth rate of the _ mode scales as M-] for pure hydrogen, deuterium or tritium discharges, where M is the mass of the working gas ion. With the inclusion of impurity ions
more » ... e growth rates of r/, mode decrease in all three kinds of plasmas with a hydrogen plasma still having the highest maximum growth rate, tritium the lowest, and deuterium in 1 between. However, the isotope effects are weaker and scale as M_ with the presence of impurity ions, where the effective mass Meff is a combination of A_ and A_, the mass number of hydrogenic and impurity ions. For the impurity mode the situation is similar tu that of the _ mode without impurity ions. Experimental database shows that the plasma energy confinement time scales as rE~A) in clean plasmas. The correlation of the theoretical results with the experimental confinement scaling is discussed. a)Permanent address:
doi:10.2172/10154987 fatcat:y2tew4f2sbe5hibujq726n4xce