HOLLOW DENSITY PROFILE ON ELECTRON-CYCLOTRON-RESONANCE HEATING JFT-2MPLASMA

The first hollow electron density profile in the central region on the JAERI Fusion Torus-2M (JFT-2M) is measured during electron cyclotron resonance heating (ECRH) with a TV Thomson scattering system (TVTS). T he peripheral region is not hollow but is accumulated due to pump-out from the central region. The hollowness increases with time but is sat urated at similar to 40ms and maintains a constant hollow ratio. The h ollowness is strongly related to the steep temperature gradient of the heated zone.