  We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed
to measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s)
accreting white dwarfs, neutron stars and stellar mass black holes in the
Galactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra)
and optical (NOAO 4m-Mosaic imaging), and a followup spectroscopy and IR
identification program. The survey has now extended through the first 6 years
of Chandra data using serendipitous sources detected in 105 distinct ACIS-I and
-S fields observed in 154 pointings and covered by 65 deep Mosaic images in V,
R, I, and H-alpha. ChaMPlane incorporates fields with galactic latitude |b| <~
12 deg and selected to be devoid of bright point or diffuse sources, with
exposure time > ~20 ksec, and (where possible) minimum NH. We describe the
scientific goals and introduce the X-ray and optical/IR processing and
databases. We derive preliminary constraints on the space density or luminosity
function of cataclysmic variables from the X-ray/optical data for 14 fields in
the Galactic Anticenter. The lack of ChaMPlane CVs in these Anticenter fields
suggests their space density is ~ 3x below the value (3 x 10^-5 pc^-3) found
for the solar neighborhood by previous X-ray surveys. Companion papers describe
the X-ray and optical processing in detail, optical spectroscopy of ChaMPlane
sources in selected Anticenter fields and IR imaging results for the Galactic
Center field. An Appendix introduces the ChaMPlane Virtual Observatory (VO) for
online access to the X-ray and optical images and source catalogs for ready
display and further analysis.
