A basic experiment on isotope scaling of transport

There is considerable divergence between theoretical predictions and tokama k experimental results for the isotopic mass effects on transport. This mot ivated a basic physics experiment in the Columbia Linear Machine [G. A. Nav ratil, J. Slough, and A. K. Sen, Phys. Plasmas 24, 184 (1982)]. Experiments were done using two different gases: hydrogen and deuterium. Measurements of particle transport driven by an ExB rotationally driven mode were made v ia the cross correlation of potential and density fluctuations. Unlike in t okamaks, the plasma parameter profiles and fluctuation spectra were maintai ned nearly invariant for both gases, thus enabling a meaningful comparison and estimation of scaling. The first series of data reveal smaller transpor t values for the deuterium plasma and a scaling that ranges as D(perpendicu lar to)proportional toA(i)(-0.6) to D(perpendicular to)proportional toA(i)( -0.8). (C) 2001 American Institute of Physics.