Self organization of high β_p plasma equilibrium with an inboard poloidal magnetic field null in QUEST

Successful production of high β_p plasmas (εβ_p 1) fully non-inductively (NI) and their long pulse sustainment with the help of modest power (<100 kW) of electron cyclotron waves is demonstrated. High β_p plasmas are found for the first time to be naturally self organized to form a stable natural inboard poloidal field null (IPN) equilibrium. A critical β_p value is identified, which defines the transition boundary from inboard limiter (IL) to IPN equilibrium. A new feature of plasma self organization is evidenced, which enhances its negative triangular shape to sustain high β_p. These results show a relatively simple method to produce and sustain high β_p plasma close to the equilibrium limit in a stable configuration exploiting its self organization property.