Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U

Global Gyrokinetic Simulation of Electron Temperature Gradient Turbulence and Transport in NSTX Plasmas

Global, nonlinear gyrokinetic simulations of electron temperature gradient (ETG) driven turbulence were carried out with the GTS code using actual experimental parameters of NSTX discharges. Our simulations reveal remarkable new features with regard to nonlinear spectral dynamics in 2D perpendicular wavenumber space. Specifically, there exists direct, strong energy coupling between high-k ETG m...

Simulation of microtearing turbulence in NSTX

Thermal energy confinement times in NSTX dimensionless parameter scans increase with decreasing collisionality. While ion thermal transport is neoclassical, the source of anomalous electron thermal transport in these discharges remains unclear, leading to considerable uncertainty when extrapolating to future ST devices at much lower collisionality. Linear gyrokinetic simulations find microteari...

Electron Bernstein Wave Research on CDX-U and NSTX

Mode-converted electron Bernstein waves (EBWs) potentially allow the measurement of local electron temperature (Te) and the implementation of local heating and current drive in spherical torus (ST) devices, which are not directly accessible to low harmonic electron cyclotron waves. This paper reports on the measurement of X-mode radiation mode-converted from EBWs observed normal to the magnetic...

"Snowflake" divertor configuration in NSTX

Detection of Disruptions in the High-β Spherical Torus NSTX

This paper describes the prediction of disruptions based on diagnostic data in the high-β spherical torus NSTX [M. Ono, et al., Nuclear Fusion 40, 557 (2000)]. The disruptive threshold values on many signals are examined. In some cases, raw diagnostic data can be used as a signal for disruption prediction. In others, the deviations of the plasma data from simple models provides the signal used ...