A segmented linear ion trap (100, 200, 414, 501) comprising: at least two discrete trapping regions for processing ions; a RF electrical potential generator for producing two RF waveforms (102, 416), and arranged to apply each to a pair of pole electrodes of the linear ion trap forming a RF trapping field component to confine ions radially; a multi-output DC electrical potential generator (103, 300) for producing multiple DC field components superimposed to the RF field component and distributed across the length of the linear ion trap to control ions axially; a control unit (104, 301, 302) configured to switch the DC electrical potentials and corresponding DC field components collectively forming a first trapping region of the at least two discrete trapping regions that is populated with ions axially confined therein to alter ion potential energy from a first ion potential energy level (121, 524) to a second ion potential energy level (122, 525) by simultaneously changing the DC electrical potentials of the first trapping region between a first DC electrical potential level (107, 119, 126, 214, 215, 219, 220) and a second DC electrical potential level (107, 122, 124, 231, 222, 224), and to enable a first ion processing step in at least one of the first and second ion potential energy levels (121, 122, 524, 525); and wherein the control unit (104, 301, 302) is configured to switch one or more of the DC electrical potentials at the second ion potential energy level (107, 124) at one side of the first trapping region to a value (125, 126, 215, 216, 220, 225) less than the minimum DC electrical potential (122, 214, 222) of the first trapping region thereby permitting the release of ions confined therein for movement along the axis of the linear ion trap by acceleration away from the first trapping region. at least two discrete trapping regions for processing ions; a RF electrical potential generator for producing two RF waveforms (102, 416), and arranged to apply each to a pair of pole electrodes of the linear ion trap forming a RF trapping field component to confine ions radially; a multi-output DC electrical potential generator (103, 300) for producing multiple DC field components superimposed to the RF field component and distributed across the length of the linear ion trap to control ions axially; a control unit (104, 301, 302) configured to switch the DC electrical potentials and corresponding DC field components collectively forming a first trapping region of the at least two discrete trapping regions that is populated with ions axially confined therein to alter ion potential energy from a first ion potential energy level (121, 524) to a second ion potential energy level (122, 525) by simultaneously changing the DC electrical potentials of the first trapping region between a first DC electrical potential level (107, 119, 126, 214, 215, 219, 220) and a second DC electrical potential level (107, 122, 124, 231, 222, 224), and to enable a first ion processing step in at least one of the first and second ion potential energy levels (121, 122, 524, 525); and wherein the control unit (104, 301, 302) is configured to switch one or more of the DC electrical potentials at the second ion potential energy level (107, 124) at one side of the first trapping region to a value (125, 126, 215, 216, 220, 225) less than the minimum DC electrical potential (122, 214, 222) of the first trapping region thereby permitting the release of ions confined therein for movement along the axis of the linear ion trap by acceleration away from the first trapping region.