W. Heidbrink

Ion Cyclotron Emission (ICE) as an Alpha Loss Diagnostic

ICE is potentially a simple & reliable qualitative diagnostic of alpha loss

Goal: Detect alpha losses wherever they occur.

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•The escaping flux is easily missed but we want to detect all losses!

Duong, NF 33 (1993) 749

fast particle expulsion by (and in phase with) TAE modes

Time [s]

n=4 n=5n=6 ..

FILD

Garcia-Munoz, ASDEX

•But localized measurements promote detailed physics understanding!

The Cons (& Pros) of Localized Loss Detectors: They are Localized in Phase

Space

Ion Cyclotron Emission (ICE) as an Alpha Loss Diagnostic

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•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)

Cauffman, NF 35 (1995) 1597

Heidbrink, NF 46 (2006) 324

ICE is a Sensitive Fast-Ion Loss Diagnostic

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Duong, NF 33 (1993) 749

•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

ICE Has Been Detected Many Ways

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•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)

Wang, NF 46 (2006) S708

Reflectometry

Magnetics

Summary of Recommendations

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•Need a feasibility study for ITER

•Measure ICE with reflectometry

•Combine with a fast-wave species mix diagnostic?