Thumbnail
Access Restriction
Open

Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Off-axis Electron Cyclotron Current Drive ♦ Current Profile ♦ Wide Range ♦ Current Drive ♦ Effective Mean ♦ Fisch-boozer Co-current ♦ Target Plasma ♦ Mhd Activity ♦ Key Element ♦ Current Profile Control ♦ Economical Steady-state Operation ♦ Advanced Tokamak Program ♦ Current Drive Efficiency ♦ Electron Beta ♦ Excellent Tool ♦ Current Off-axis ♦ Ohkawa Counter-current ♦ Excellent Agreement ♦ Minor Radius ♦ High Performance Discharge ♦ Extensive Computational Modeling ♦ Recent Experiment ♦ Partial Cancellation ♦ Low Beta ♦ Electron Cyclotron Current Drive ♦ Theoretical Viewpoint ♦ Strong Deterioration ♦ Fokker-planck Code Cql3d ♦ Key Option
Abstract ABSTRACT: Electron cyclotron current drive is a key option for driving current off-axis in a tokamak, as needed for example for current profile control or for suppression of neoclassical tearing modes. Experiments in DIII–D at low beta have shown that the partial cancellation of the Fisch-Boozer co-current by the Ohkawa counter-current can cause strong deterioration of the current drive efficiency at larger minor radius. However, more recent experiments at higher power have shown that the loss in efficiency can be mostly recovered if the target plasma has higher electron beta, βe. The improvement in efficiency with beta can be understood from a theoretical viewpoint by applying the Fokker-Planck code CQL3D, which shows excellent agreement with experiment over a wide range of parameters, thereby validating the code as an effective means of predicting the ECCD. Electron cyclotron current drive (ECCD) is a key element of the advanced tokamak program on DIII–D, the goal of which is to develop high performance discharges with the potential for economical steady-state operation. Extensive computational modeling has shown that ECCD is an excellent tool for sustaining the current profile which supports improved confinement and stability as well as for stabilizing MHD activity like neoclassical
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Learning Resource Type Article