Abstract: A Multifunctional Capillary System is located within and between a single compensation chamber (CC) and the evaporator of a loop heat pipe. It provides: vapor-liquid interface control for all gravity states from the micro-gravity condition of space (near 0-g) through the earth's gravitational condition (1-g), with liquid supply to the evaporator via wicking from the CC in micro-gravity, and for all orientations (tilts) of the CC-evaporator assembly in earth gravity. As a single compensation chamber is used, dual compensation chamber penalties of weight and wide-temperature-variation are avoided. The system has combined, parallel wicking structure, paths, and joints for micro-gravity and 1-g liquid acquisition. The wick system is comprised of an axial-groove, evaporator-core secondary wick—concentric, contiguous, and in intimate contact with the primary evaporator wick. This secondary wick mates to a porous vane assembly in the CC.