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Analysis of XP819 Data on Fast Ion Transport during TAE Avalanches

Explore the runtime and detailed analysis of experimental data related to avalanches and fast ion transport in XP819 for the Energetic Particles Group. Focus on understanding the complex interactions and thresholds involved in TAE events. Plan to extend studies to higher densities and H-modes with upgraded diagnostics.

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Analysis of XP819 Data on Fast Ion Transport during TAE Avalanches

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  1. Status, summary and plans for Analysis of data from XP819; fast ion transport during TAE avalanches E D Fredrickson for Energetic Particles Group

  2. Summary of runtime: • First day, April 4: 3 shots, establish plasma • Second day, April 10: • 128424-128431 attempt Avalanches with Deuterium • 128432-128438 power scan with B up to 95 kV, no TAE. • 128439-128444 power scan with C up to 95 kV, no TAE • 128445-128448 Scan with B&C up to 75/70 kV, Avalanche • 128451-128455 NPA scan with early RF power scan • 128456 More Source A coverage for q-profile evolution • Third day, June 24 - slow start w/rebuilt source C • 130089-130096 TF scan with source A, waiting for C • 130097-130111 Search for avalanches • 130122-130135 Still no avalanches • Fourth day, July 14 - 2 hours for TF scan • 130703-130704 4.5 kG, avalanches restored • 130705-130707 5.5 kG, avalanche threshold found • 130709-130712 Power scan to 3.4MW, no avalanches!

  3. Analysis Status for TF scan: • LRDFIT09/TRANSP analysis has been done for: • 5.5 kG power scan shots, with good match to neutron rate: • 130705a04 2.4 MW, TAE/avalanches • 130706a02 2.2 MW, TAE/avalanches • 130707a03 2.0 MW, TAE/weak avalanches • 3.5 kG power scan shots, with good match to neutron rate: • 130709a01 2.0 MW, no TAE • 130710a03 2.4 MW, no TAE • 130711a01 2.8 MW, TAE modes after 240 ms • 130712a01 3.2 MW, possibly weak TAE avalanche at 239 ms. • 4.5 kG shots • 130703, 130704 still to be analyzed • Shots 130089 - 130096 will provide q-evolution with only source A, at 3.5, 4.5 and 5.5 kG

  4. Toroidal field (VAlfvén) scaling of avalanche threshold is complex • More beam power needed to reach TAE avalanche threshold at low field, but didn't translate to fast/tot scaling of threshold. • Implies other parameters are important (q profile evolution, fast profile, etc.). • Additional analysis of this data, and earlier Beam voltage scan data will be done. • Also necessary to move beyond cartoon characterization of stability thresholds.

  5. Good data collected on scaling of TAE/Avalanche thresholds with Vfast/VAlfvén • Scaling is not as simple as previous (2007) data suggested. • Extensive NOVA and M3D-K analysis needed to understand scaling. • New FIDA (and NPA) data showing the impact of Avalanches on fast ion transport will be analyzed in parallel (M Podesta) for APS invited talk. • Next year avalanche studies will be extended to higher/lower density and H-modes utilizing upgrades to reflectometers and new BES diagnostic

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