The invention is related to a trapped ion mobility spectrometer (TIMS device) and proposes to use higher order (order N>2) linear multipole RF systems to accumulate and analyze ions at an electric DC field barrier, either pure higher order RF multipole systems or multipole RF systems with transitions from higher order towards lower order, e.g. from a linear octopolar RF system (N=4) to a linear quadrupole RF system (N=2) in front of the apex of the electric DC field barrier.