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The National Spherical Torus Experiment (NSTX) produces plasmas, with toroidal aspect ratio as low as 1.25 and plasma currents up to 1.5 MA, which can be heated by up to 6 MW High‐Harmonic Fast Waves and up to 7 MW of deuterium Neutral Beam Injection. With these capabilities, NSTX has already made considerable progress in advancing the scientific understanding of high performance plasmas needed for low‐aspect‐ratio reactor concepts and for ITER. In transport and turbulence research on NSTX, the role of magnetic shear is being elucidated in discharges in which electron energy transport barriers are observed. Scaling studies indicate a weaker dependence on plasma current than at conventional aspect ratio and a significant dependence on toroidal field (BT).

Plasma density fluctuations are being investigated experimentally in CSDX, a magnetized plasma column. We show that an effective Reynolds number of the plasma is directly proportional to axial magnetic field strength B and inversely proportional to the ion‐neutral collsion frequency, which in our experiment is proportional to the neutral gas pressure. As B is increased, plasma density fluctuations grow in amplitude and evolve to either a multi‐mode or turbulent state, depending on the gas pressure. In this final state, correlation dimension estimates of the fluctuations are low for the high pressure case (D ∼ 2), but are high and unsaturated for the low pressure case. Together these results present a familiar but incomplete picture of a plasma turbulent transition that features the breakup of an attractor.