A method and apparatus are disclosed for improving ion mobility spectrometry by using a fast and spatially wide ion gate based on local RF field barrier opposed to a switching DC field. Alternatively, the speed and charge throughput of ion mobility separator are improved by arranging coaxial mobility cell followed by conical coaxial ion channel. The improvement accelerates the ion mobility analysis and improves charge throughput and dynamic range of the IMS. The invention is particularly suited for rapid dual gas chromatography, fast CE. Preferably, the accelerated and wide bore IMS is coupled to a multi-reflecting time-of-flight mass spectrometer with a fast encoded orthogonal acceleration. Speed and sensitivity of IMS with fast pulsing MR-TOF make it practical to arrange analytical methods of comprehensive and orthogonal separation in multiple analytical dimensions.