In order to improve the particle control capability of the divertorand to demonstrate the possibility of a dense and cold divertor withhigh confinement plasmas, a closed divertor study has been carried outon the JFT-2M tokamak. When a strong gas puff is applied into thedivertor chamber, a baffling effect is revealed by enhanced radiationlocalization and high neutral pressure in the divertor chamber, lowcore fuelling and sustainment of core confinement quality. Thebaffling effect is further enhanced with E × B flow and/or current inthe scrape-off layer by applying divertor biasing. A dense and colddivertor state (nediv ≈ 4 × 1019m-3 and Tediv ≈ 4 eV), together with the improved confinement modes, can be obtained by strong gas puffing. Furthermore, the improved core confinement is not affectedsignificantly in the high density region (e/neG < 0.7). TheUEDA code simulation reproduces the baffling effect and a dense andcold divertor plasma with a closed divertor structure.