Energy confinement in ohmic H mode in TUMAN-3

It is shown that boronization resulted in an improvement of plasma performance in both the ordinary ohmic regime and the ohmic H mode. In a boronized vessel, higher density and higher plasma current were achieved, allowing the parametric dependences of the energy confinement time on density, plasma current and input power to be studied. A weak τE dependence on and pronounced dependences on Ip and Pinput in the ohmic H mode are contradictory to neo-Alactor scaling. τohm.H modeE corresponds to DIII-D/JET H mode scaling for auxiliary heated plasmas. At maximum plasma current (155 kA), τE reaches 30 ms. From the observed favourable τE dependence on Ip a further improvement of energy confinement is to be expected after upgrading TUMAN-3 with the aim of increasing Ip up to 200 kA. (author). 17 refs, 6 figs