Field-Particle Correlation Experiments on DIII-D
Frontiers Science Proposal
• Under weakly collisional conditions, collisionless interactions
between electromagnetic fields and individual particles lead
to particle energization
– This process leads to perturbations in the particle velocity
distribution functions that are correlated with the
electromagnetic fields
– Spatially coincident measurements of the electromagnetic
fields and particle velocity distribution functions can be
used to compute directly the rate of particle energization
– Well diagnosed DIII-D shots may enable the application of
this field-particle correlation method to explore the particle
energization arising from the damping of turbulent
fluctuations in the edge region
– Field-particle correlations can identify heating mechanism
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Context: Diagnosing Particle Energization
using Field-Particle Correlations
• Main Scientific Challenge
– Determining particle energization using
measurements of field and distribution functions
– Distinguishing different mechanisms of particle
energization using velocity-space signature
• Relevance
– Particle energization and plasma heating
impacts a wide range of systems, from solar
corona to black hole accretion disks to fusion
plasmas
• Techniques used to date
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Nonlinear kinetic simulations of electrostatic waves
Nonlinear gyrokinetic simulations of turbulence
Measurements of electron acceleration in LAPD Expt
MMS spacecraft measurements
Context: Diagnosing Particle Energization
using Field-Particle Correlations
• Scientific progress to date
– Development of theoretical foundation for the
field-particle correlation method
– Application to analyze ion and electron heating
in gyrokinetic turbulence and reconnection sims
– Analyzed electron acceleration in LAPD Expts
– Analysis of electron heating in magnetosphere
• Key gap issue
– Application of method to experimental
measurements on DIII-D will pave the way for
widespread use of the technique to determine
directly particle energization in expts
– Method can be used to distinguish different
mechanisms of particle energization
– Experiments on plasma turbulence,
anomalous ion heating, and electron
acceleration will benefit from using this method
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DIII-D Proposal
Determining Particle Energization
• Scientific question to be tested on DIII-D
– Directly diagnose the conversion of
electromagnetic energy into particle energy
and determine mechanism responsible
– Directly determine heating of particles
in edge region using field-particle correlation
• Experimental Technique
– Measure particle distribution functions
and electromagnetic field fluctuations at
the same position in the DIII-D discharge
• Analysis done / planned
– Nonlinear gyrokinetic simulations of
turbulence can predict heating mechanism
– Velocity space signature generated by
field-particle correlation analysis points to
energization mechanism
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DIII-D Proposal
Determining Particle Energization
• Why DIII-D? / Why now?
– DIII-D boast sophisticated
diagnostics to measure
electromagnetic fluctuations and
particle velocity distributions.
– Fundamental new approach to
study particle energization in
edge region and the responsible mechanism can be pioneered on DIII-D
• Related studies elsewhere
– Fast ion studies on DIII-D already use similar approaches to study waveparticle interactions
– Application of innovative field-particle correlation method to electron
acceleration in LAPD Expts
– Use of field-particle correlations to determine heating in space plasmas
• Impact of successful result
– Development of new experimental method to determine rate of
particle energization in edge and the physical mechanism responsible
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Experiment Details
Field-Particle Correlations
• Key hardware elements required
– Neutral Beam Injection for fast ions
– 3D coils to achieve shape of field
to enable in situ measurements
• Key measurements required
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ECE diagnostic
Toroidal mode magnetic field diagnostics
B dot measurement in space and time
Interferometers
Electric field measurements
Fast ion diagnostics
• Particular preparation necessary
– Determine shot parameters that yield interesting ion or electron heating
regimes
– Determine what spatially coincident particle and field measurements
can be made on DIII-D
– Theory to apply field-particle correlations to distributed measurements
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Experiment Team
• University personnel
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Greg Howes, U Iowa, Nonlinear kinetic plasma theory and simulation
Kristopher Klein, U Michigan, Kinetic plasma theory and simulation
Mark Koepke, WVU, Experimental Alfven modes, nonlinear dynamics
Jose Boedo, UCSD, Experimental edge physics and ion confinement
Bill Heidbrink, UC Irvine, Fast particle and TAE experiments on DIII-D
• DIII-D personnel
– George McKee, GA, Experimental fusion turbulence
– Auna Moser, GA, Experimental divertor physics
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