Neoclassical transport in the helical reversed-field pinch.

Breakdown of Onsager Symmetry in Neoclassical Transport Theory

Neoclassical transport theory is developed in a Lagrangian rather than the usual Eulerian formulation. We show that an underlying asymmetry exists in the neoclassical pinch and bootstrap effects and demonstrate the physical basis of the Onsagesymmetry relationship in the pinch-bootstrap duality. It is suggested that low frequency turbulence can destroy the bootstrap current at levels too low to...

Microtearing modes in reversed field pinch plasmas.

In the reversed field pinch RFX-mod strong electron temperature gradients develop when the single-helical-axis regime is achieved. Gyrokinetic calculations show that in the region of the strong temperature gradients microtearing instabilities are the dominant turbulent mechanism acting on the ion Larmor radius scale. The quasilinear evaluation of the electron thermal conductivity is in good agr...

Healing of magnetic islands in stellarators by plasma flow

Recent experiments from the Large Helical Device (LHD) indicate that the plasma flow can play a primary role in “healing” vacuum magnetic islands in stellarators. The observed elimination of magnetic islands tends to occur at low collisionality and high plasma β. A model explaining this phenomenon is developed reminiscent of ’mode locking/unlocking’ physics of tokamak and reversed field pinch e...

Classical impurity ion confinement in a toroidal magnetized fusion plasma.

High-resolution measurements of impurity ion dynamics provide first-time evidence of classical ion confinement in a toroidal, magnetically confined plasma. The density profile evolution of fully stripped carbon is measured in MST reversed-field pinch plasmas with reduced magnetic turbulence to assess Coulomb-collisional transport without the neoclassical enhancement from particle drift effects....

Use of helical fields to allow a long pulse Reversed Field Pinch