Cross-machine NTM physics studies and implications for ITER

Control or avoidance of Neoclassical Tearing Modes (NTMs) will be necessary for good performance in ITER. Recent joint ITPA/IEA and other experiments on JET, DIII-D and ASDEX Upgrade are reported providing new insights into the transport effects, seeding, underlying physics, and threshold scaling of NTMs. Studies highlight the key role of sawteeth in triggering NTMs, with advances made in prediction and control in ITER-relevant high fast particle content plasmas. A range of trigger mechanisms are found in ELMy H-mode and hybrid scenarios, with 3 types of NTM impacting performance. Underlying physics scales towards increased NTM sensitivity in ITER, suggesting further measurement and development of control strategies are important. (author)