Theoretical consideration of collision electron spectroscopy (CES) for gaseous media analysis and experimental results on CES detector are presented. It is demonstrated that a diffusion path confinement for characteristic electrons provides a possibility to measure electrons energy distribution function and to find characteristic spectra of species at high (up to atmospheric) gas pressure. Simple micro-plasma CES detector of two plane parallel electrode configuration with current-voltage measurement in afterglow of helium glow discharge may be designed to operate at a high gas pressure up to atmospheric one. Experimental electron energy spectra of pair He metastables collisions in dependence of interelectrode gap are discussed.
