  A small-scale, two-phase (liquid/gas) xenon time projection chamber (Xurich
II) was designed, constructed and is under operation at the University of
Zurich. Its main purpose is to investigate the microphysics of particle
interactions in liquid xenon at energies below 50 keV, which are relevant for
rare event searches using xenon as target material. Here we describe in detail
the detector, its associated infrastructure, and the signal identification
algorithm developed for processing and analysing the data. We present the first
characterisation of the new instrument with calibration data from an internal
83m-Kr source. The zero-field light yield is 15.0 and 14.0 photoelectrons/keV
at 9.4 keV and 32.1 keV, respectively, and the corresponding values at an
electron drift field of 1 kV/cm are 10.8 and 7.9 photoelectrons/keV. The charge
yields at these energies are 28 and 31 electrons/keV, with the proportional
scintillation yield of 24 photoelectrons per one electron extracted into the
gas phase, and an electron lifetime of 200 $\mu$s. The relative energy
resolution, $\sigma/E$, is 11.9 % and 5.8 % at 9.4 keV and 32.1 keV,
respectively using a linear combination of the scintillation and ionisation
signals. We conclude with measurements of the electron drift velocity at
various electric fields, and compare these to literature values.
