1ST OHMIC H-MODES IN ALCATOR C-MOD

Ohmic H modes have been achieved in ALCATOR C-MOD with toroidal fields up to B(T) almost-equal-to 5.25 T and line averaged densities up to n BAR(e) almost-equal-to 1.4 x 10(20) m-3 with less than 1 MW of input p ower. In ELM-free cases at lower toroidal fields, the energy confineme nt increases by at least 60% and the particle confinement increases by more than a factor of two. The ELM-free H modes appear to fit the thr eshold power scaling observed on other tokamaks, P/S (MW/m2) = 4.4 x 1 0(-3) nBAR(e)B(T) (10(19) m-3.T), up to power densities of about 0.15 MW/m2. At higher toroidal fields, ELMy H modes were observed after the injection of lithium pellets at about half of the scaled threshold po wer density. All of these results were obtained with molybdenum plasma facing components and the ELM-free H modes were obtained without boro nization or other wall coatings.