Tokamak Magnetic Turbulence over the Safety-Factor Range0.6<q<3

Edge gradient and safety-factor effects on electrostatic turbulent transport in tokamaks

“…The large scrape-off region permits operation with either small edge gradients (without material limiters) or large edge gradients (with material limiters). We also compare the present results with previous measurements of magnetic turbulence, performed over the same qa range in Tokapole II [13].From these variations we infer several significant features of electrostatic turbulence. The turbulence is weakly dependent on qa.…”

“…3 Fig. 4, as are magnetic fluctuations [13]. There is a systematic hundredfold variation of the magnetic fluctuation amplitude with qa, in contrast to the relative invariance of the electrostatic quantities.…”

“…7, which shows the qa dependence of the energy flux from electrostatic fluctuations, the energy flux from magnetic fluctuations (evaluated from the expression for stochastic field transport, using previously measured magnetic fluctuations [13]), and the total energy flux. The energy flux from electrostatic fluctuations, F/^, is given by F/, = 3{pE)/2B, where p and E are the fluctuating electron pressure and poloidal electric field, and 0 denotes an ensemble average.…”

“…To compare the various transport fluxes, we have assumed that these fluxes are constant on a magnetic surface. This assumption was based on simultaneous fluctuation amplitude [13]) and the total energy flux, as a function of safety factor. measurements made at three poloidal locations (top, bottom, and outer sides) and three toroidal locations (nonsimultaneously).…”

Experimental Investigation of the Magnetic Fluctuations in a Toroidal Plasma

“…Much effort has gone into determining how large an effect the microturbulence has on the global confinement. Magnetic fluctuations have been measured in many tokamaks [2][3][4][5][6]. There is much similarity in the results of these fluctuation measurements, and thus it appears that the nature of the microturbulence in tokamaks is rather universal.…”