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SUMMARY of FAST PARTICLE PHYSICS

2002 U.S. Transport Task Force Meeting Annapolis, Maryland April 3 – 6, 2002. SUMMARY of FAST PARTICLE PHYSICS. Boris Breizman, Raffi Nazikian & Energetic Particle Group. 6+1 oral talks 3 posters Interesting discussions. Fast Particle Studies on JET (Relevant to Burning Plasma)

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SUMMARY of FAST PARTICLE PHYSICS

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  1. 2002 U.S. Transport Task Force Meeting Annapolis, Maryland April 3 – 6, 2002 SUMMARY of FAST PARTICLE PHYSICS Boris Breizman, Raffi Nazikian & Energetic Particle Group 6+1 oral talks 3 posters Interesting discussions

  2. Fast Particle Studies on JET (Relevant to Burning Plasma) S. Sharapov • Gamma-ray tomography and spectroscopy implemented [12C(3He,ng)14N etc.] RF-induced pinch of fast ions observed Time-resolved measurements coming

  3. Fast Particle Studies on JET (continued) • 4He beam ions accelerated to MeVs by 3rd harmonic ICRH - Fusion alpha simulation in non-activating discharges - Sawtooth stabilization observed - TAEs and EAEs observed • New results on Alfvén spectroscopy - Alfvén modes in reverse shear discharges explained - Accurate safety factor measurements possible

  4. Alfvén Cascade Theory with Toroidal Coupling Effects B. Breizman • Cascade mode emerges at low frequency as an Energetic Particle Mode, and evolves into the TAE mode as the frequency approaches the TAE gap. Normalized frequency Time • Non-linear analysis is underway • Detailed fitting of JET data is underway

  5. Study of Energetic Particle Confinement in Beam Blip Experiments W. Heidbrink, D. Darrow Inject a short deuterium beam pulse into ohmically heated deuterium plasma Measure decaying neutron signal from beam-target reactions Use TRANSP to simulate classical neutron signal No significant deviation from classical slowing down Issue: Can this blip technique be used on top of a long-pulse NBI to study high-performance regimes?

  6. Beam Blip Experiments (contd.)

  7. Progress in Calculations of Alfvén Eigenmodes in Stellarators D. Spong - New code describes Alfven continuum in 3-D - W7-AS data indicates possible Helical AE - first attempts made to calculate eigenmodes Next steps: Stability and non-linear analysis pending

  8. Deviations from Neoclassical Scaling Laws due to Large Orbit Excursions J. Christiansen Implications for moderate aspect ratio devices like JET, especially in ITB regimes Full orbit analysis required for accurate description

  9. Possibility of Enhanced Thermal Ion Heating in STs D. Gates Ti>Te observed in NSTX Proposition : Fast beam ions transfer energy to CAEs. CAEs produce stochastic heating of thermal ions. Requirement: dB/B≥5x10-4 for 32 modes. Consistent description of wave saturation mechanism needed! Internal reflectometer measurements urgently needed! Alternative interpretation: rotation+trapped-passing ion friction. Multiple Compressional Alfvén Eigenmodes observed (local amplitudes unknown).

  10. General Comments ALL PARTICLES ARE EQUAL, BUT SOME ARE MORE EQUAL THAN OTHERS Specific example: energetic particles and wave-particle resonances. Phase-space probing is working well in studying the mechanisms of fast particle transport (both theoretically and experimentally). Can we extend this approach to thermal particles? It makes sense to present transport modeling results in terms of test particle dynamics. This should reveal the most sensitive areas of phase space. The information needed can be readily extracted from the ongoing gyro-kinetic simulations).

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