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W. Heidbrink

Ion Cyclotron Emission (ICE) as an Alpha Loss Diagnostic. W. Heidbrink. Goal: Detect alpha losses wherever they occur. ICE is potentially a simple & reliable qualitative diagnostic of alpha loss. The Cons (& Pros) of Localized Loss Detectors: They are Localized in Phase Space.

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W. Heidbrink

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  1. Ion Cyclotron Emission (ICE) as an Alpha Loss Diagnostic W. Heidbrink Goal: Detect alpha losses wherever they occur. ICE is potentially a simple & reliable qualitative diagnostic of alpha loss

  2. The Cons (& Pros) of Localized Loss Detectors: They are Localized in Phase Space fast particle expulsion by (and in phase with) TAE modes Garcia-Munoz, ASDEX n=6 .. n=6 .. n=5 n=4 n=5 n=4 magnetics FILD Time [s] • The escaping flux is easily missed but we want to detect all losses! R0 V2 V2 • But localized measurements promote detailed physics understanding! Duong, NF 33 (1993) 749

  3. Ion Cyclotron Emission (ICE) as an Alpha Loss Diagnostic • Compressional Alfven waves are driven by a bump-on-tail in the fast-ion velocity distribution • Electron Landau damping is the dominant damping mechanism • ICE occurs in scrapeoff where electrons are slow and phase velocity is high (small kll) • CAE occurs near edge where electrons are fast and phase velocity is low (large kll) R0 Cauffman, NF 35 (1995) 1597 V2 V2 Heidbrink, NF 46 (2006) 324

  4. ICE is a Sensitive Fast-Ion Loss Diagnostic R0 Duong, NF 33 (1993) 749 V2 • Second harmonic at outer edge is virtually always strong  ~ 50 MHz on ITER • To my knowledge, every tokamak with fast-ion losses that has looked for ICE has seen it V2

  5. ICE Has Been Detected Many Ways Wang, NF 46 (2006) S708 R0 V2 Reflectometry • In large-aspect ratio devices, the eigenfunction is extensive  Measurable at many poloidal locations • Magnetic coils in inner wall (PDX), top of machine (TFTR), and outer wall (many devices) • ICRF Antenna (JET) • Reflectometry of CAE (DIII-D, NSTX) Magnetics V2

  6. Summary of Recommendations R0 • Need a feasibility study for ITER • Measure ICE with reflectometry • Combine with a fast-wave species mix diagnostic? V2 V2

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