A mass spectrometer, comprising: an ion source of the type being configured to continuously generate ions from a sample being supplied thereto, a trapped ion mobility separator (TIMS) being configured to receive the generated ions in accumulated volumes thereof, and further being configured to output these accumulated volumes in pulses of ion species that have been separated in time by their ion mobility, wherein the trapped ion mobility separator is configured to use parallel ion accumulation (PATIMS), wherein ions are accumulated in an accumulation unit separated by their ion mobility while scanning the ions according to their ion mobility in a subsequent scanning unit, and the ions are transferred, after each scan, from the accumulation unit to the scanning unit, wherein the trapping ion mobility spectrometer comprises an elongated tunnel comprising tunnel electrodes, divided into the ion accumulation unit and the ion mobility scanning unit, where a gas flow drives the ions through the elongated tunnel, the spectrometer furthermore comprising an RF voltage supply unit for RF voltages at quadrants of the tunnel electrodes where a quadrupolar RF field inside the tunnel holds the ions near to the axis of the device, and DC voltage supply units for the generation of the electric field barrier in axial direction within the two tunnel units, contacting maximum barrier-defining electrodes (33, 37) at locations along the tunnel axis spaced apart from one another, wherein chains of resistors between the electrodes in both tunnel units (11a, 11b) produce the two electric DC field barriers for the ion accumulation unit and for the ion mobility scanning unit, such that the gas flow drives the ions against the ramps of the electric field barriers, separating the ions by their ion mobility, wherein during the ion mobility scan, the voltage applied to maximum barrier-defining electrode of the scanning unit is steadily or step-wise gradually decreased, thereby releasing ion species with increasing mobility, resulting in an ion mobility spectrum, a first mass filter being configured to receive the ion species and select precursor ions therefrom to be fragmented, a fragmentation cell being configured to receive and fragment the selected precursor ions, a second mass filter being configured to receive and select fragment ions resulting from the precursor ions by the fragmentation, and an ion detector being configured to receive and measure an ionic output from the second mass filter. an ion source of the type being configured to continuously generate ions from a sample being supplied thereto, a trapped ion mobility separator (TIMS) being configured to receive the generated ions in accumulated volumes thereof, and further being configured to output these accumulated volumes in pulses of ion species that have been separated in time by their ion mobility, wherein the trapped ion mobility separator is configured to use parallel ion accumulation (PATIMS), wherein ions are accumulated in an accumulation unit separated by their ion mobility while scanning the ions according to their ion mobility in a subsequent scanning unit, and the ions are transferred, after each scan, from the accumulation unit to the scanning unit, wherein the trapping ion mobility spectrometer comprises an elongated tunnel comprising tunnel electrodes, divided into the ion accumulation unit and the ion mobility scanning unit, where a gas flow drives the ions through the elongated tunnel, the spectrometer furthermore comprising an RF voltage supply unit for RF voltages at quadrants of the tunnel electrodes where a quadrupolar RF field inside the tunnel holds the ions near to the axis of the device, and DC voltage supply units for the generation of the electric field barrier in axial direction within the two tunnel units, contacting maximum barrier-defining electrodes (33, 37) at locations along the tunnel axis spaced apart from one another, wherein chains of resistors between the electrodes in both tunnel units (11a, 11b) produce the two electric DC field barriers for the ion accumulation unit and for the ion mobility scanning unit, such that the gas flow drives the ions against the ramps of the electric field barriers, separating the ions by their ion mobility, wherein during the ion mobility scan, the voltage applied to maximum barrier-defining electrode of the scanning unit is steadily or step-wise gradually decreased, thereby releasing ion species with increasing mobility, resulting in an ion mobility spectrum, a first mass filter being configured to receive the ion species and select precursor ions therefrom to be fragmented, a fragmentation cell being configured to receive and fragment the selected precursor ions, a second mass filter being configured to receive and select fragment ions resulting from the precursor ions by the fragmentation, and an ion detector being configured to receive and measure an ionic output from the second mass filter.