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(abbreviated) We aim to study the inner wind of the well-known AGB star CWLeo. Different diagnostics probing different geometrical scales have pointedtoward a non-homogeneous mass-loss process: dust clumps are observed atmilli-arcsec scale, a bipolar structure is seen at arcsecond-scale andmulti-concentric shells are detected beyond 1". We present the first ALMA Cycle0 band 9 data around 650 GHz. The full-resolution data have a spatialresolution of 0".42x0".24, allowing us to study the morpho-kinematicalstructure within ~6". Results: We have detected 25 molecular lines. Theemission of all but one line is spatially resolved. The dust and molecularlines are centered around the continuum peak position. The dust emission has anasymmetric distribution with a central peak flux density of ~2 Jy. Themolecular emission lines trace different regions in the wind accelerationregion and suggest that the wind velocity increases rapidly from about 5 R*almost reaching the terminal velocity at ~11 R*. The channel maps for thebrighter lines show a complex structure; specifically for the 13CO J=6-5 linedifferent arcs are detected within the first few arcseconds. The curvedstructure present in the PV map of the 13CO J=6-5 line can be explained by aspiral structure in the inner wind, probably induced by a binary companion.From modeling the ALMA data, we deduce that the potential orbital axis for thebinary system lies at a position angle of ~10-20 deg to the North-East and thatthe spiral structure is seen almost edge-on. We infer an orbital period of 55yr and a binary separation of 25 au (or ~8.2 R*). We tentatively estimate thatthe companion is an unevolved low-mass main-sequence star. The ALMA data henceprovide us for the first time with the crucial kinematical link between thedust clumps seen at milli-arcsecond scale and the almost concentric arcs seenat arcsecond scale.

ALMA data suggest the presence of a spiral structure in the inner wind of CW Leo