High Bootstrap Fraction Plasmas with ITBs C. Kessel Global formula for determining IP and N to generate a given bootstrap current fraction At BT = 5 T, N = 2.0 yields IP = 300 kA At BT = 8 T, N = 2.0 yields IP = 450 kA For fBS = 1 Make large fBS plasmas with ITBs, and then manipulate the current profile by using ICRF central heating and/or modulating ICRF off-axis heating

High Bootstrap Current Fraction Plasmas with ITBs ICRF resonances at r/a ≈ 0.5 to induce ITB BT = 4.5 T, f = 80 MHz at R-a/2 BT = 5.5 T, f = 70 MHz at R+a/2 BT = 6.3 T, f = 80 MHz at R+a/2 Can ICRF H-modes be formed at lower IP values? Greenwald density limit at low IP, nL > 1.41020 for ITB Would use central ICRF heating to arrest peaking/impurity accumulation Limits operation to 4.5 & 5.5 T to have two resonances in plasma for 70 and 80 MHz Would like to turn off-axis ICRF on and off, and produce an RMS bootstrap current profile So may not need on-axis ICRF to reduce peaking, which allows 6.3 T case to be used, can the frequency be stretched even higher than 80 MHz?