[en] We report the results of experiments on DIII-D where quasi steady-state H-mode plasma with low amplitude Edge Localized Modes (ELMs) were maintained for 5 seconds. Within one second from the onset of the H-mode, most plasma parameters reach their asymptotic values (/bar n//sub e/ ∼ 7 /times/ 10¹³ cm/sup /minus/3/, /tau//sub E/ ≅ 100 ms, Z/sub eff/ = 1.7) and the electron density and temperature profiles are no longer evolving. By this time, frequent ELMs and effective helium wall conditioning limit the rate of increase of /bar n//sub e/ (≤10% of the beam fueling rate) and maintain the total radiated power form impurities at a constant level. 5 refs., 2 figs