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

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 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

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

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 wave-particle 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

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 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

Experiment Team University personnel DIII-D personnel 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