ALPHA PARTICLES IN THE SOLAR WIND EXHIBIT SEVERAL FASCINATING FEATURES THAT ARE POORLY UNDERSTOOD INCLUDING FLOW SPEEDS GREATER THAN THE PROTON FLOW SPEED TEMPERATURES LARGER THAN THE PROTON TEMPERATURE TEMPERATURE ANISOTROPY AND A RELATIVE ABUNDANCE THAT VARIES SYSTEMATICALLY WITH WIND SPEED AND SUNSPOT NUMBER. THE MAIN GOAL OF THIS PROJECT IS TO UNDERSTAND THE ORIGINS OF THESE PHENOMENAAND TO DISCOVER HOW THEY RELATE TO LARGER QUESTIONS ABOUT THE ORIGIN AND EVOLUTION OF THE SOLAR WIND. THE INVESTIGATION WILL INVOLVE AN INTEGRATED PROGRAM OF ANALYTIC THEORY GLOBAL NUMERICAL SIMULATIONS OF THE SOLAR WIND AND ANALYSIS OF SPACECRAFT DATA. THE EVOLUTIONOF ALPHA PARTICLES IN THE SOLAR WIND DEPENDS UPON SEVERAL KINETIC PROCESSES SUCH AS THE COLLISIONLESS DISSIPATION OF TURBULENCE AND THE DECELERATION OF ALPHA PARTICLES BY PLASMA INSTABILITIES. THE RESEARCH TEAM HAS DEVELOPED ANALYTIC THEORIES THAT DESCRIBE SEVERAL OF THESE PROCESSES AND AS PART OF THIS PROJECT WILL DEVELOP AN ANALYTIC THEORY DESCRIBING HOW THE TURBULENT HEATING POWER IS APPORTIONEDBETWEEN PROTON HEATING ELECTRON HEATING AND ALPHA-PARTICLE HEATING. THE RESEARCH TEAM WILL USE THESE ANALYTIC THEORIES TO INCORPORATE THESE KINETIC PROCESSES INTO A 1D (FLUX-TUBE) SOLAR-WIND MODEL AND THE 3D ALFVEN WAVE SOLAR MODEL (AWSOM) A COMPUTER CODE THAT CARRIES OUT GLOBAL SIMULATIONS OF THE SOLAR CORONA AND SOLAR WIND. THE INVESTIGATORS WILL CARRY OUT A SERIES OF NUMERICAL SIMULATIONS WITH THESE CODES AND WILL COMPARE THE SIMULATION RESULTS WITH SPACECRAFT OBSERVATIONS TO TEST AND VALIDATE THE SIMULATIONS. THIS PROJECT WILL ANSWER SEVERAL SCIENCE QUESTIONS INCLUDING THE FOLLOWING. (1) CAN SOLAR-WIND HEATING AND ACCELERATION BY ALFVEN-WAVE TURBULENCE EXPLAIN THE ALPHA-TO-PROTON DIFFERENTIAL FLOW VELOCITY IN THE SOLAR WIND? (2) WHAT IS THE HELIOCENTRIC DISTANCE AT WHICH THE ALPHA-TO-PROTON DIFFERENTIAL FLOW VELOCITY REACHES ITS MAXIMUM VALUE? (3) HOW IMPORTANT IS THE PLASMA HEATING THAT RESULTS FROM THE DECELERATION OF ALPHA PARTICLES IN THE SOLAR WIND? (4) CAN TURBULENCE-BASED SOLAR-WIND MODELS EXPLAIN THE OBSERVED VARIATIONS OF THE HELIUM ABUNDANCE WITH SOLAR-WIND SPEED AND SUNSPOT NUMBER? (5) IS THE VARIATION OF HELIUM ABUNDANCE WITH SUNSPOT NUMBERRELATED TO AN INCREASED FRACTION OF LOW-SPEED WIND COMING FROM ACTIVE REGIONS DURING SOLAR MAXIMUM? (6) CAN TURBULENT HEATING EXPLAIN THE OBSERVED PREFERENTIAL HEATING AND TEMPERATURE ANISOTROPY OF ALPHA PARTICLES? THE RESEARCH TEAM WILL ALSO CARRY OUT 1D SIMULATIONS AND DATA ANALYSIS THAT WILL ADDRESS MINOR-ION HEATING IN THE SOLAR WIND. THIS PROJECT ADDRESSES THE HIGH-LEVEL SCIENCE GOAL FROM THE HELIOPHYSICS DECADAL SURVEY TO ``DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE.''