  The LUX (Large Underground Xenon) detector is a two-phase xenon Time
Projection Chamber (TPC) designed to search for WIMP-nucleon dark matter
interactions. As with all noble element detectors, continuous purification of
the detector medium is essential to produce a large ($>$1ms) electron lifetime;
this is necessary for efficient measurement of the electron signal which in
turn is essential for achieving robust discrimination of signal from background
events. In this paper we describe the development of a novel purification
system deployed in a prototype detector. The results from the operation of this
prototype indicated heat exchange with an efficiency above 94% up to a flow
rate of 42 slpm, allowing for an electron drift length greater than 1 meter to
be achieved in approximately two days and sustained for the duration of the
testing period.
