Turbulent Fluctuations with the Electron Gyro-Scale in NSTX Plasmas
نویسندگان
چکیده
Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from an electron gyro-scale turbulence driven by the electron temperature gradient. To check whether such turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) confirm the existence of density fluctuations in the range of wave numbers k e=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code indicate that the observed turbulence is indeed driven by the electron temperature gradient. PACS numbers: 52.55.Fa, 52.35.Qz, 52.35.Ra
منابع مشابه
Experimental tests of paleoclassical transport
Predictions of the recently developed paleoclassical transport model are compared with data from many toroidal plasma experiments: electron heat diffusivity in DIII-D, C-Mod and NSTX ohmic and near-ohmic plasmas; transport modeling of DIII-D ohmic-level discharges and of the RTP ECH “stair-step” experiments with eITBs at low order rational surfaces; investigation of a strong eITB in JT-60U; H-m...
متن کاملTurbulent electron thermal transport in tokamaks
The origin of anomalous electron thermal turbulence from spatial gradients in magnetized plasmas is described. Laboratory experiments demonstrating key features of drift waves are reviewed. The turbulent electromagnetic fields produce an anomalous transport that scales with both the gradient parameters and microscopic plasma scale length parameters. The change from the micro-scale dominated gyr...
متن کاملOverview of results from the National Spherical Torus Experiment (NSTX)
The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand ele...
متن کاملQuantitative Comparisons of DIII–D Turbulence Measurements to Gyro-Kinetic and Gyro-Fluid Turbulence Simulations
Experimental turbulence and transport characteristics in DIII–D plasmas have been compared with similar quantities calculated from gyro-kinetic and gyro-fluid turbulence simulations. Turbulent radial correlation lengths ∆r from DIII–D L–mode plasmas scale as 5 to 10 ρs (ρs = ion gyro-radius evaluated using the electron temperature) and are independent of the poloidal magnetic field. Comparisons...
متن کاملWhistler Wave Cascades in Solar Wind Plasma
Nonlinear three dimensional, time dependent, fluid simulations of whistler wave turbulence are performed to investigate role of whistler waves in solar wind plasma turbulence in which characteristic turbulent fluctuations are characterized typically by the frequency and length scales that are respectively bigger than ion gyro frequency and smaller than ion gyro radius. The electron inertial len...
متن کامل