IN THIS PROPOSAL TO THE SUB-ELEMENT LABORATORY ASTROPHYSICS WE AIM TO DEEPEN OUR UNDERSTANDING OF X-RAY SPECTRA FROM EXTRASOLAR SOURCES OF HIGHLY CHARGED IONS INTERACTING WITH NEUTRAL GASES. THE MOST COMMON SOURCE OF THESE X-RAYS IS FROM CHARGE EXCHANGE (CX) AND IS OBSERVED IN THE INTERSTELLAR MEDIUM (ISM) GALACTIC CENTER NEAR SUPERNOVA AND EXTRASOLAR STELLAR WINDS. THE PROPOSAL WILL INTRODUCE A NEW JOINT EXPERIMENTAL FACILITY FOR X-RAY SPECTROSCOPY. THE MEASUREMENTS WILL BE AUGMENTED WITH CHARGE EXCHANGE CROSS SECTION AND SPECTRAL COMPUTATIONS. ..THE CX MEASUREMENTS WILL BE CONDUCTED AT THE CLEMSON ELECTRON BEAM ION SOURCE (EBIS) FACILITY (CO-I'S SOSOLIK AND MARLER) WHICH HAS THE ABILITY TO PRODUCE A BEAM OF CHARGE STATE SELECTED IONS (UP TO H- AND HE-LIKE CHARGE STATES) FROM INJECTED NEUTRAL TARGETS (E.G. PERIOD 2 AND 3 ELEMENTS) WITH TUNABLE KINETIC ENERGIES. THE PI FOGLE WILL PROVIDE A COLD TARGET RECOIL ION MOMENTUM SPECTROMETER (COLTRIMS) SYSTEM FROM AUBURN UNIVERSITY TO BE MATED WITH A HIGH RESOLUTION X-RAY CALORIMETER SPECTROMETER FROM GSFC TO BE OPERATED BY CO-I'S PORTER AND LEUTENEGGER (GSFC) AND BROWN (LLNL). IN CONJUNCTION THESE COMPONENTS WILL ALLOW FOR COMPLETE VELOCITY-DEPENDENT MEASUREMENTS OF X-RAY EMISSION AND STATE-SELECTIVITY FOR CX WITH HCIS THAT SHOW PREDOMINANT LINES IN THE 1/4- AND 3/4-KEV BANDS. THE COLTRIMS SYSTEM WILL PRODUCE A NEUTRAL BEAM INTERACTION TARGET THAT WILL BE CROSSED BY AN ION BEAM. THE NEUTRAL TARGETS WILL INCLUDE BUT NOT BE LIMITED TO HE H2 CO AND CO2 TO BE CHOSEN DUE TO THEIR RELEVANCE TO ASTRONOMICAL OBSERVATIONS. UPON CX ELECTROSTATIC ANALYZERS COLLECT THE IONIZED TARGET RECOILS AND THE CHARGED-CHANGED PROJECTILES ON TIME- AND POSITION-SENSITIVE DETECTORS IN COINCIDENCE. THIS ALLOWS FOR A PRECISE MEASUREMENT OF MOMENTUM TRANSFER THAT CORRELATES DIRECTLY TO THE CAPTURE STATE OF THE CX ELECTRON(S). IT ALSO ALLOWS FOR THE RELATIVE DETERMINATION OF MULTI-ELECTRON PROCESSES SUCH AS DOUBLE CAPTURE AUTOIONIZATION WITH RESPECT TO SINGLE ELECTRON CAPTURE. AN INCORPORATED TRIGGERABLE X-RAY SPECTROMETER WILL PROVIDE THE X-RAY SIGNATURE IN COINCIDENCE WITH INFORMATION ABOUT THE BEAM AND TARGET PRODUCTS FROM THE COLTRIMSS WILL RESULT IN A TRUE TRIPLE COINCIDENCE MEASUREMENT. ..COUPLED WITH THE EXPERIMENTAL MEASUREMENTS WILL BE COMPLEMENTARY COMPUTATIONAL RESULTS. THE MOST RELEVANT AND RELIABLE THEORETICAL METHODS FOR MODELING CX ARE MOLECULAR-ORBITAL CLOSE-COUPLING (MOCC) APPROACHES WHICH REQUIRE EXTENSIVE MOLECULAR STRUCTURE AND COLLISION DYNAMICS CALCULATIONS. FOR MULTI-ELECTRON TARGETS SUCH AS HE OR MOLECULES MULTI-ELECTRON PROCESSES CAN BECOME IMPORTANT BUT HAVE NOT BEEN INCORPORATED ROUTINELY IN MODELS. CO-I STANCIL AND HIS TEAM WILL MERGE CURRENT MOCC CODE WITH THE ATOMIC PACKAGE AUTOSTRUCTURE TO COMPUTE SINGLE AND DOUBLE ELECTRON CAPTURE PROCESSES WHICH WILL BE INCORPORATED IN CASCADE/X-RAY EMISSION MODELS FOR BENCHMARKING AGAINST THE MEASUREMENTS. .