SUMMARY of FAST PARTICLE PHYSICS

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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
61 oral talks 3 posters Interesting discussions
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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
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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
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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
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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?
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Beam Blip Experiments (contd.)
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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
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Deviations from Neoclassical Scaling Laws due to
Large Orbit Excursions J. Christiansen Implicati
ons for moderate aspect ratio devices like
JET, especially in ITB regimes Full orbit
analysis required for accurate description
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Possibility of Enhanced Thermal Ion Heating in
STs D. Gates TigtTe observed in NSTX
Proposition Fast beam ions
transfer energy to CAEs. CAEs produce
stochastic heating of thermal ions.
Requirement dB/B5x10-4 for 32
modes. Consistent description of wave
saturation mechanism needed! Internal
reflectometer measurements urgently
needed! Alternative interpretation
rotationtrapped-passing ion friction.
Multiple Compressional Alfvén Eigenmodes
observed (local amplitudes unknown).
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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).