BACKGROUND: MEASUREMENTS OF NEUTRAL HELIUM (HE) BY NASA'S IBEX SPACECRAFT HAVE IDENTIFIED TWO DISTINCT SIGNALS: (1) A PRIMARY SIGNAL CORRESPONDING TO THE EXPECTED CONDITIONS IN THE LOCAL INTERSTELLAR MEDIUM (LISM); AND (2) A SECONDARY SIGNAL WHICH REPRESENTS A SLOWER AND WARMER POPULATION WITH A VELOCITY VECTOR OFFSET BY ABOUT 19 DEGREES FROM THE PRIMARY SIGNAL. IN PRESENTING THEIR FINDINGS KUBIAK ET AL (2014) OFFERED FOUR POSSIBLE EXPLANATIONS FOR THE ORIGIN OF THE SECONDARY POPULATION WHICH THEY DUBBED THE WARM BREEZE : (1) IT COMES FROM THE OUTER HELIOSHEATH REGION OF THE HELIOSPHERE WHERE THE INTERSTELLAR PLASMA IS SLOWED HEATED AND DEFLECTED AROUND THE HELIOPAUSE; (2) IT IS NOT A SECOND POPULATION BUT RATHER A BROADENED VERSION OF THE PRIMARY POPULATION WHERE THIS BROADENING IN ITS VELOCITY DISTRIBUTION MAY BE DUE TO ELASTIC COLLISIONS WITH SOLAR WIND IONS; (3) IT COMES FROM OUTSIDE THE LOCAL INTERSTELLAR CLOUD IF THE BOUNDARY OF THE CLOUD IS NEARBY AS SUGGESTED BY SEVERAL INVESTIGATIONS; (4) IT COMES FROM LARGE SCALE NON-UNIFORMITIES ON THE ORDER OF 10 000 AU IN THE LISM PLASMA WHERE VARIATIONS IN THE PLASMA VELOCITY AND TEMPERATURE ON THESE SCALES COULD RESULT IN MULTIPLE NEUTRAL HELIUM POPULATIONS. SCIENCE GOALS: THE GOAL OF THIS PROPOSAL IS TO UNDERSTAND THE INTERACTION BETWEEN HE OF INTERSTELLAR ORIGIN AND THE HELIOSPHERE. HELIUM MAKES UP ABOUT 10% OF THE NEUTRAL MATTER IN THE LISM AND ENTERS THE HELIOSPHERE BY CROSSING THE HELIOPAUSE. OTHER NEUTRAL ATOMS FROM THE LISM SUCH AS HYDROGEN (H) CHARGE-EXCHANGE WITH PROTONS ON MEAN FREE PATH LENGTHS WHICH ARE A SIGNIFICANT FRACTION OF THE SIZE OF THE HELIOSPHERE AND TEND TO CHARGE-EXCHANGE IN THE SLOWED RELATIVELY DENSE PLASMA JUST UPSTREAM OF THE HELIOPAUSE. THE RESULT IS THAT SOME FRACTION OF H-ATOMS ARE SLOWED HEATED AND DEFLECTED AROUND THE HELIOPAUSE AT THE SAME TIME GIVING RISE TO AN ENHANCED DENSITY OF NEUTRALS UPSTREAM OF THE HELIOSPHERE KNOWN AS THE HYDROGEN WALL . THE IMPACT OF CHARGE-EXCHANGE WITHIN THE H-WALL IS BOTH A FILTRATION OF LISM ATOMS AND THE CREATION OF A SLOWED AND HEATED SECONDARY POPULATION SOME OF WHICH ALSO ENTERS THE HELIOSPHERE. THE OBJECTIVE OF THIS PROPOSAL IS TO COMPUTE THE ANALOGUES PROCESS WHICH WILL GENERATE A HE-WALL AND A POPULATION OF SECONDARY HE AND TO DETERMINE HOW THE FEED-BACK OF HE ATOMS CHARGE-EXCHANGING WITH HE IONS WILL IMPACT THE STRUCTURE OF THE INTERSTELLAR BOUNDARY REGION. METHODOLOGY: WE PROPOSE TO INVESTIGATE THE PHYSICAL PROCESSES INVOLVED IN THE INTERACTION OF HE WITH THE HELIOSPHERE TAKING INTO ACCOUNT BOTH THE ION AND NEUTRAL PHASES ALONG WITH A VARIETY OF COLLISIONAL PROCESSES THAT CONNECT THESE TOGETHER AND TO THE UNDERLYING PLASMA AND H DISTRIBUTIONS. THE HUNTSVILLE TEAM HAS DEVELOPED ADVANCED SIMULATION TOOLS FOR THE INTERACTION OF THE LISM WITH THE SOLAR WIND. THE PI DEVELOPED A CODE THAT TRACKS NEUTRAL H AS PARTICLES THROUGH THE HELIOSPHERE INCLUDING CHARGE-EXCHANGE COLLISIONS WITH PROTONS. CHANGES IN ENERGY AND MOMENTUM ASSOCIATED WITH COLLISIONS ARE APPLIED TO SOURCE TERMS FOR THE MHD EQUATIONS SOLVED FOR THE IONS. IN ADDITION WE HAVE A SOPHISTICATED POST-PROCESSING ANALYSIS TOOL WHICH INTEGRATES THE SOURCES OF NEUTRAL ATOM FLUX THAT CAN BE SEEN BY IBEX. THE SECONDARY HE SIGNAL IN THE IBEX DATA WILL BE ISOLATED AND WILL BE USED TO CONSTRAIN THE PARAMETERS USED IN THE SIMULATION CODE. SIMILARLY THE PROPERTIES OF THE SECONDARY HE SIGNAL FROM THE SIMULATIONS WILL BE USED TO BETTER IDENTIFY AND INTERPRET THE SECONDARY SIGNAL IN THE IBEX HE DATA. RELEVANCE: THIS PROPOSAL ADDRESSES SCIENCE GOAL: 3. DETERMINE THE INTERACTION OF THE SUN WITH THE SOLAR SYSTEM AND THE INTERSTELLAR MEDIUM DESCRIBED IN THE HELIOPHYSICS DECADAL SURVEY. OUR ANALYSIS WILL ALLOW FOR SPECIFIC THEORIES ABOUT TWO-POPULATION HE SIGNAL SEEN BY IBEX TO BE TESTED IN A SELF-CONSISTENTLY COUPLED H-HE-PLASMA MODEL. THIS PROPOSAL FITS INTO HSR SCIENCE AREA 7 OUTER HELIOSPHERE AND INTERSTELLAR BOUNDARY .