Abstract: An ion mobility spectrometer having a housing with an analyzer positioned therein. The analyzer includes first and second longitudinally spaced apart electrodes which are preferably cylindrical in configuration. The space between the electrodes defines an analytical gap which is in communication with a source of carrier gas. An ionization source such as a .beta.-emitter or corona discharge is juxtaposed with the analytical gap and source of sample media and includes an ion aperture for ions to enter said gap. The spectrometer includes an ion detector for measuring ions. An electrical controller connected to the first and second electrodes for impressing a first direct potential and second periodic asymmetrical potential capable of creating a transverse electrical field therebetween during the flow of carrier gas in the analytical gap. Preferably, a third low voltage ripple potential is impressed in series with the first two potentials.