The article treats the recent development of quasi-steady ELMy high β_p H mode dis- charges with enhanced confinement and high fi stability, where long sustainment time, an increase in absolute fusion performance and extension of the discharge regime towards low q95 (～3) are empha- sized. After modification to the new W shaped pumped divertor, a long heating time (9 s) with a high total heating energy input of 203 MJ became possible without a harmful increase in impurity and particle recycling. In addition, optimization of the pressure profile characterized by the double transport barriers, optimum electron density and/or high triangularity δ made it possible to extend the performance in long pulses. The DT equivalent fusion gain Q_DT~eq ≈ 0.1 (δ = 0.16) was sustained for ～9 s (～50_τE, ～10τ_p~*) and Q_DT~eq ≈ 0.16 (δ = 0.3) for 4.5 s at I_p = 1.5 MA. In the latter case with higher δ, an H factor (=τE/τ_E~ITER89PL) of～2.2, β_N ≈ 1.9 and β_P ≈ 1.6 were sustained with 60-70% of the non-inductively driven current. In the low q95 (～3) region, the β limit was improved by the high δ (～0.46) shape, where β_N ≈ 2.5-2.7 was sustained fOr ～3.5 s with the collisionality close to that of ITER-FDR plasmas. The limit of the edge α parameter in the ELMy phase δ which is the main reason behind the improved β limit in a long pulse at high δ. The sustainable value of β_N H also increases with δ. Sustainable β_N is limited by the onset of low n resistive modes. Direct measurement of island width shows agreement with the neoclassical tearing mode theory.
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