Observations of sheared radial electric-field effects on turbulence suppression

Abstract

Significant effects of sheared transverse electric fields in plasmas on both turbulent fluctuations and drift waves are experimentally demonstrated with improvement in plasma confinement for the first time in the tandem mirror GAMMA 10. These electric-shear effects are performed on the basis of a factor of 2 advance in ion-confining potential formation. For analyzing these phenomena in detail, we develop a novel electrostatic ion-energy spectrometer array consisting of five spectrometer units. The spectrometer arrays have the characteristic advantage of having no disturbances from potential-producing electron-cyclotron wave heated energetic electrons. Totally four array arms having each a 90°separation located on each GAMMA 10 end wall make it possible to observe two-dimensionally resolved radial-distribution profiles of plug and/or central potentials as well as radially produced shear of electric fields along with the earlier-described fluctuation signals simultaneously.