1. ITPA Diagnostics 4/06 The Importance of Fast-Ion Profile Measurements in ITER W. Heidbrink Three examples from DIII-D Conclusion Fast-ion D  (FIDA) Technique Heidbrink, PPCF 46 (2004) 1855.

2. ITPA Diagnostics 4/06 The Fast-ion Profile is Not a Flux Function Even without instabilities, in current devices, the fast-ion density profile is not a flux function. With instabilities, wave- particle resonances occur preferentially with some classes of particles (e.g., co- passing alphas interact more strongly with TAEs than counter-passing alphas). The resultant transport alters the spatial profile in a non- uniform fashion. Kiptily, NF 45 (2005) L21 JET Gamma-ray Data

3. ITPA Diagnostics 4/06 Fast-ion Redistribution Occurs in Current Devices Three discharges with different levels of mode activity Fast-ion redistribution broadens current profile Optimal redistribution triggers an internal transport barrier Calculations suggest a similar phenomenon may occur in ITER. Wong, NF 45 (2005) 30. DIII-D Magnetics Data MSE-derived equilibria

4. ITPA Diagnostics 4/06 Fast-ion Profile Flattens in Fully-Noninductive, High- Performance AT Discharge Flattening occurs in highest beta phase Neutron rate deviates From TRANSP prediction during this phase Integrated FIDA  signal shows profile becomes flat Agrees with analysis of driven beam current: Need flat beam density profile to match current profile Classical Data Murakami, Phys. Pl. 13 (2006) in press. DIII-D Fast-ion D  Data

5. ITPA Diagnostics 4/06 Fast-ion D-Alpha Diagnostic Measures Flat Fast- ion Profiles during Strong Alfven Activity Heidbrink, IAEA Synopsis (2006) DIII-D data If ITER operates with reversed shear, Reversed Shear Alfven Eigenmodes (RSAE) are likely.

6. ITPA Diagnostics 4/06 Vertical Views of the Fast-ion Profile Address a Crucial ITER Issue On both theoretical and empirical grounds, the fast-ion profile will vary with major radius R, not just minor radius. A key scientific issue for ITER is alpha-driven instabilities and the resultant alpha transport. Vertical camera views are far more sensitive to the expected transport than horizontal views. Internal fluctuation diagnostics (such as high bandwidth reflectometers or interferometers) are also crucial for the study of alpha-driven instabilities.