A wire-discharge chamber containing a hollow cathode was designed and tested at reduced pressure. Immobile ionization waves in the form of circular strata and 2-D wave beams were obtained from the mixture of air and ethanol vapor. Wave images in polygonal and spiral forms were recorded. Patterns of ionization waves having topologically nontrivial forms featuring separatrix were found. Diffraction effects of wave optics associated with the scattering of ionization waves on obstacles and slots (the Fraunhofer diffraction) were observed for the first time.