SCIENCE GOALS&OBJECTIVES: WE PROPOSE TO USE SOFT AND HARD X-RAY (SXR HXR) AND EXTREME ULTRAVIOLET (EUV) MEASUREMENTS FROM MINXSS-1 RHESSI SDO AND HINODE TO MEASURE ELEMENTAL ABUNDANCES IN THE SOLAR CORONA TO BETTER UNDERSTAND THE ORIGINS AND EVOLUTION OF HOT CORONAL PLASMA BOTH DURING SOLAR FLARES AND ABOVE ACTIVE REGIONS. IN PARTICULAR WE WILL ANSWER QUESTIONS SURROUNDING THE PARTITIONING OF ENERGY BY FLARE RECONNECTION-DRIVEN ENERGY RELEASE AND BY THE CORONAL HEATING PROCESS BY STUDYING THERMAL AND WAVE ENERGY INPUT IN A VARIETY OF FLARES AND ACTIVE REGIONS WITH POSSIBLE APPLICATIONS TO UNDERSTANDING FLARE INITIATION BY E.G. WAVES. MEASUREMENTS OF ELEMENTAL ABUNDANCES IN HOT CORONAL PLASMA PROVIDE CRUCIAL INFORMATION ON MASS FLOWS WITHIN AND INTO THE CORONA IN RESPONSE TO HEATING. THE COMPOSITION OF THE SOLAR ATMOSPHERE VARIES FROM PHOTOSPHERE TO CORONA WITH THE VARIATIONS ORGANIZED BY FIRST-IONIZATION POTENTIAL (FIP) WHERE LOW-FIP ABUNDANCES TEND TO BE ENHANCED IN THE CORONA RELATIVE TO THE PHOTOSPHERE. THIS FIP BIAS SUGGESTS THAT THE FRACTIONATION PROCESSES OCCUR IN THE CHROMOSPHERE WHERE LOW-FIP ELEMENTS (E.G. FE CA SI MG) ARE IONIZED WHILE HIGH-FIP ELEMENTS (E.G. C O AR) REMAIN NEUTRAL AND IS MOST LIKELY DUE TO THE PONDEROMOTIVE FORCE ASSOCIATED WITH ALFV N WAVES. THEREFORE MEASUREMENTS OF THE FIP BIAS IN THE CORONA AND ITS EVOLUTION OVER BOTH SHORT AND LONG TIMESCALES CAN HELP ILLUMINATE THE WAVE ACTIVITY AND THE ORIGINS OF HOT CORONAL PLASMA DURING BOTH FLARES AND WITHIN EVOLVING ACTIVE REGIONS. SPECTRALLY- AND TEMPORALLY-RESOLVED X-RAY AND EUV OBSERVATIONS PROVIDE CRITICAL DIAGNOSTIC INFORMATION ON HOW PLASMA IS HEATED. THE STANDARD MODEL POSITS THAT HOT PLASMA IN SXR-EMITTING LOOPS ORIGINATES IN THE CHROMOSPHERE EVAPORATING INTO THE CORONA AS IT IS HEATED BY COLLISIONS FROM DOWNWARD-ACCELERATED ELECTRONS. HOWEVER RECENT STUDIES SUGGEST THAT A SIGNIFICANT PORTION OF THE PLASMA INCLUDING THE HOTTEST PART OF THE TEMPERATURE DISTRIBUTION IS HEATED IN SITU IN THE CORONA AND PRIOR STUDIES OF FLARE AND ACTIVE REGION ABUNDANCES HAVE YIELDED MIXED RESULTS. AN INVERSE FIP EFFECT (AR ENHANCED RELATIVE TO CA) HAS EVEN BEEN DETECTED IN SUNSPOTS. RESOLVING THESE AMBIGUITIES REQUIRES MEASURING ABUNDANCES OF MULTIPLE ION SPECIES SENSITIVE TO DIFFERENT TEMPERATURES SIMULTANEOUSLY TO SELF-CONSISTENTLY DETERMINE THE ORIGINS OF THE VARIOUS PARTS OF THE CORONAL TEMPERATURE DISTRIBUTION. MISSION DATA: WE WILL COMBINE FULL-SUN SPECTRA FROM MINXSS-1 (SXR) RHESSI (HXR) AND SDO/EVE (EUV) ALONG WITH SPATIALLY-RESOLVED EUV IMAGES AND SPECTRA FROM SDO/AIA AND HINODE/EIS AND X-RAY IMAGES FROM HINODE/XRT. DATA ANALYSIS METHODOLOGY: WE WILL USE OBSERVED INTENSITIES TO DETERMINE THE TEMPERATURE DISTRIBUTION AND THE COMPOSITION OF HOT (~2-50 MK) CORONAL PLASMA DURING A VARIETY OF SOLAR FLARES AND NON-FLARING QUIESCENT PERIODS. WE WILL LEVERAGE OUR ALREADYPROVEN DEM INVERSION TECHNIQUES (WARREN ET AL. 2013 APJ 770 115; CASPI ET AL. 2014 APJL 788 L31) WITH STRAIGHTFORWARD EXPANSIONS TO INCLUDE VARIABLE ABUNDANCES TO COMBINE AND SIMULTANEOUSLY ANALYZE THE DATA SETS FROM THESE MULTIPLE INSTRUMENTS IN A SELF-CONSISTENT MANNER THAT WILL WORK ROBUSTLY WITH ANY COMBINATION OF THE EXISTING DATA SETS ALLOWING US TO STUDY ALL TIME PERIODS DURING THE SDO EPOCH (MAY 2010 TO PRESENT). DERIVED ABUNDANCES WILL BE COMPARED WITH VARIOUS MODELS OF FIP FRACTIONATION; RESONANT CORONAL WAVES ON A CLOSED LOOP NONRESONANT CORONAL WAVES IN OPEN OR CLOSED FIELD AND PHOTOSPHERIC WAVES ALL PRODUCE RECOGNIZABLY DIFFERENT FRACTIONATION PATTERNS. IN THIS WAY ABUNDANCE PATTERNS LEAD TO INFERENCES ABOUT WAVES WHICH THEN LEAD TO INFERENCES ABOUT HEATING MECHANISMS. RELEVANCE: WE DIRECTLY ADDRESS THE HGI SCOPE OF ADVANCING CRITICAL SOLAR PHYSICS TOPICS USING MULTIPLE MISSIONS. WE ADDRESS OBJECTIVE 1.4 OF NASA S 2014 SCIENCE PLAN AND THE HELIOPHYSICS DECADAL SURVEY GOAL #4 SPECIFICALLY THROUGH SUB-GOAL SHP-2.