  We present a systematic search for periodic X-ray sources in 10 Galactic
globular clusters (GCs) utilizing deep archival Chandra observations. By
applying the Gregory-Loredo algorithm, we detect 28 periodic signals among 27
independent X-ray sources in 6 GCs, which include 21 newly discovered ones in
the X-ray band. The remaining 4 GCs exhibit no periodic X-ray sources, mainly
due to a relatively lower sensitivity of the data. Through analysis of their
X-ray timing and spectral properties, complemented with available optical and
ultraviolet information, we identify 21 of these periodic sources as
cataclysmic variables (CVs). Combining with 11 periodic CVs in 47 Tuc similarly
identified in the X-ray band, we compile the most comprehensive sample to date
of GC CVs with a probable orbital period. The scarcity of old, short-period CVs
in GCs compared to the Galactic inner bulge and solar neighborhood, can be
attributed to both a selection effect favouring younger, dynamically-formed
systems and the hindrance of CV formation through primordial binary evolution
by stellar dynamical interactions common to the GC environment. Additionally,
we identify a significant fraction of the GC CVs, most with an orbital period
below or within the CV period gap, as probable magnetic CVs, but in the
meantime there is a deficiency of luminous intermediate polars in the GC sample
compared to the solar neighborhood.
