Survey of H-mode transition and confinement from ASDEX upgrade 'H-mode standard shot'

The H-mode standard shot of ASDEX Upgrade provides an overview of the long term evolution of machine conditions and scatter of H-mode power threshold and confinement. This type-I ELMy H-mode is run every day of plasma operation since 1999. After a long opening for in-vessel work, the power threshold drops rapidly by about 50% over 100 discharges and then much slower by about 20% over the remaining 1000 plasma discharges made in a campaign. At the natural density without gas puffing, confinement increases by about 30% over about 500 discharges. Afterwards the peak-to-peak scatter is about 20%, smaller at high density. Conditioning causes changes of edge density and temperature, similar to the confinement degradation observed with gas puffing.