Publications

Mar, 2012

Journal

Experimental Investigation and Validation of Neutral Beam Current Drive for ITER Through ITPA Joint Experiments

Joint experiments investigating the off-axis neutral beam current drive (NBCD) capability to be utilized for advanced operation scenario development in ITER were conducted in four tokamaks (ASDEX Upgrade (AUG), DIII-D, JT-60U and MAST) through the international tokamak physics activity (ITPA). The following results were obtained in the joint experiments, where the toroidal…

Mar, 2012

Journal

Integrated modelling of steady-state scenarios and heating and current drive mixes for ITER

Recent progress on ITER steady-state (SS) scenario modelling by the ITPA-IOS group is reviewed. Code-to-code benchmarks as the IOS group's common activities for the two SS scenarios (weak shear scenario and internal transport barrier scenario) are discussed in terms of transport, kinetic profiles, and heating and current drive (CD) sources using various transport codes. We…

Jul, 2011

Journal

Demonstration of ITER operational scenarios on DIII-D

The DIII-D programme has recently initiated an effort to provide suitably scaled experimental evaluations of four primary ITER operational scenarios. New and unique features of this work are that the plasmas incorporate essential features of the ITER scenarios and anticipated operating characteristics; e. g. the plasma cross-section, aspect ratio and value of I/aB of the D…

Jul, 2011

Journal

Beam-ion confinement for different injection geometries

The DIII-D tokamak is equipped with neutral beam sources that inject in four different directions; in addition, the plasma can be moved up or down to compare off-axis with on-axis injection. Fast-ion data for eight different conditions have been obtained: co/counter, near-tangential/near-perpendicular and on-axis/off-axis. Neutron measurements during short beam pulses asse…

Jul, 2011

Journal

Validation of on- and off-axis neutral beam current drive against experiment in DIII-D

Neutral beam current drive (NBCD) experiments in DIII-D using vertically shifted plasmas to move the current drive away from the axis have clearly demonstrated robust off-axis NBCD. Time-dependent measurements of magnetic field pitch angles by the motional Stark effect diagnostic are used to obtain the evolution of the poloidal magnetic flux, which indicates a broad off-ax…

Jul, 2011

Journal

Evidence for Fast-Ion Transport by Microturbulence

Cross-field diffusion of energetic ions by microturbulence is measured during neutral-beam injection into the DIII-D tokamak. Fast-ion D-alpha, neutron, and motional Stark effect measurements diagnose the fastion distribution function. As expected for transport by plasma turbulence, anomalies relative to the classical prediction are greatest in high temperature plasmas, at…

Jun, 2011

Journal

Simulations of KSTAR high performance steady state operation scenarios

We report the results of predictive modelling of high performance steady state operation scenarios in KSTAR. Firstly, the capabilities of steady state operation are investigated with time-dependent simulations using a free-boundary plasma equilibrium evolution code coupled with transport calculations. Secondly, the reproducibility of high performance steady state operation…

Jun, 2011

Journal

Off-axis neutral beam current drive for advanced scenario development in DIII-D

Modification of the two existing DIII-D neutral beamlines is planned to allow vertical steering to provide off-axis neutral beam current drive (NBCD) peaked as far off-axis as half the plasma minor radius. New calculations for a downward-steered beam indicate strong current drive with good localization off-axis so long as the toroidal magnetic field, B-T, and the plasma cu…

Jun, 2011

Journal

Non-inductive current drive and transport in high beta(N) plasmas in JET

A route to stationary MHD stable operation at high beta(N) has been explored at the Joint European Torus (JET) by optimizing the current ramp-up, heating start time and the waveform of neutral beam injection (NBI) power. In these scenarios the current ramp-up has been accompanied by plasma pre-heat (or the NBI has been started before the current flat-top) and NBI power up…

May, 2011

Journal

Prospects for Off-Axis Neutral Beam Current Drive in the DIII-D Tokamak

Off-axis neutral beam (NB) current drive (CD) (NBCD) has the potential to supply substantial off-axis CD for the demonstration steady-state, Advanced Tokamak scenarios. A modification of the two existing DIII-D NB beamlines is proposed to allow off-axis CD with NB injection (NBI) vertically steered to drive current as far off axis as half the plasma radius. The profile and…

Mar, 2011

Journal

Momentum Transport in DIII-D Discharges with and Without Magnetohydrodynamics (MHD) Activity