Goals of experiment: document and study

1. XP513: NSTX/MAST Identity Experiments on iITB Formation and Evolution: ITPA TP-8.1(Peng, Field, R Bell, Menard, etc) • Goals of experiment: document and study • iITB formation and evolution in H-mode plasmas on NSTX/MAST • Dependence of driven and ExB flow shear on input momentum • Flow shear and q-profile effects on iITB and low-k turbulence • Motivation: turbulence suppression & microinstability drive • Zone (i ~ NC) starts deeper (r/a ~ 0.5) and moves out • Evolves to broader Ti profile (r/a  0.7 – 0.9!), sustained • Strong coupling to high toroidal flow shear, already verified in ‘04 • Produced on August 8, 2005, via 116318 long-pulse H-Mode: • NBI energy and power varied: 100 – 65kV, 7 – 3MW; & step down • 11 in 23 shots with: >1s, low MHD duration = 0.2-0.5s > tf • Good documentation: CHERS, MSE; MHD, NPA spectra, EFITs • Results useful to other ISD, T&T, energetic ion mode, JNB studies

2. Long-Pulse Results Are Consistent with Earlier Suspicion of Mechanisms That Limit Maximum Rotation  Limiting Velocity? Higher EB & PB Lower EB & PB Long-Pulse Toroidal Rotation Velocity, Vf @ 110 cm (km/s) MHD-Quiet Energetic Ion MHD & Possible Depletion Increasing n Global MHD Locked Mode Time (s) • iITB-like behavior remains • New stationary Vf profile, MHD-quiescent plasma for ~ 200 ms • Data analysis and modeling underway

3. Coincidental Events of EPM, TM, Reconnection, Da Spikes with Vt and Snare Cataloged in the Study of iITB Evolution and Momentum Transport CAE/GAE (kHz) 117532 TAE/EPM-“Fishbone” (kHz) Ti (R) 1.5 R(m) 1.0 Vt (R) Neutron Rate, Sn (Rec = reconnection) (T = tearing mode) “Stationary” Plasma • Identified changes in momentum source & sink • “Stationary” plasma should reveal intrinsic momentum transport () mechanisms, affecting iITB. • Need to map out regime of stationary plasma as part of momentum transport study. Da EPM T T T EPM Rec Rec Rec Da Da Da Da Da Da Da Da Spikes

4. Coincidental Events of EPM, TM, Reconnection, Da Spikes with Vt and Snare Cataloged in the Study of iITB Evolution and Momentum Transport CAE/GAE (kHz) 117532 TAE/EPM-“Fishbone” (kHz) 1.5 R(m) 1.0 Vt (R) Neutron Rate, Sn (Rec = reconnection) (T = tearing mode) “Stationary” Plasma • Identified changes in momentum source & sink • “Stationary” plasma reveals intrinsic momentum transport () mechanisms, affecting iITB. • Need to map out regime of stationary plasma for momentum transport study. Da EPM T T T EPM Rec Rec Rec Da Da Da Da Da Da Da Da Spikes

5. Tearing Mode Near Edge Restrains Outward Evolution of iITB-Like Region (B1) toward the H-mode edge (B2) – Located by nC-VI Profile (LCFS to be Determined) LCFS? LCFS?

6. Discussion and Needed Analysis for Publication • New stationary regime in NSTX in 2005: • Sustained H98 > 1 for ~ 4tE; other cases only for ~ tE [TRANSP, Te()] • Stationary *AE spectrum, small ELMs, Vt(R), Sn, no MHD [MHD stability] • Stationary energetic ion distribution including *AE-induced loss [Medley, Fredrickson] • Hints of stationary oscillations at f ~ 10, 20, 30 kHz [USXR spectrum analysis] • Strong candidate plasmas for detailed transport analysis, including ITB, f • Transitions in and out of this regime: • Entered regime following EPM, with coincidental fast ion loss & Da spike • Exited regime following fast reconnection (q-related); fast ion loss & Da spike • ITB evolution, profiles: • Identified role of periphery tearing mode (TM) in determining “foot point” of Vf shear (which dominates Er shear and determines iITB region) • Transition coincidental with disappearance of TM, allowing iITB to nearly reach “ETB,” which also shows increased Ti-ped (~250eV) • Back-transition linked to reconnection-induced loss of fast ions and b • Potential physics interests • Broadest pressure profile for H98 ~ 1 so far only in ST • Mechanism may shed light on similar regimes in tokamaks