2-DIMENSIONAL DIVERTOR SIMULATION ON JT-60U

Divertor and scrape-off layer (SOL) plasmas were simulated in the JT-60U geometry with the UEDA code. Experimentally measured T-e profiles with 15-ch Langmuir probes and heat flux profiles with an IRTV camera at the divertor prates were globally fit well with chi(perpendicular to) = 2-4 m(2)/s for ohmic and L-mode discharges. The electron density and the particle amplification factor are maximized when T-e(div) approximate to 20 eV in an open divertor configuration. A further increase in particle flux leads to penetration of neutrals to the X-point. Although baffle plates can reduce the neutral density around the main plasma, particle recycling and heat load on the baffle plates becomes significant when the aperture is narrower than 40 cm in JT-60U. Closing the private region is effective to drop the neutral particle density near the X-point. A slot-like divertor shape with divertor gas puffing was found to be required to achieve cold divertor plasmas with particle fluxes at an H-mode level.