# US 9,437,412 B2 · Multi-electrode ion trap > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,412 B2 - Document ID: US9437412B2 - Status: Granted - Kind: B2 - Application number: 14/801,642 - Filed: 2015-07-16 - Published: 2015-11-12 - Granted: 2016-09-06 - Earliest claimed: 2005-06-27 - Assignees: Thermo Finnigan LLC - Applicants: Thermo Finnigan LLC - Inventors: Alexander Alekseevich Makarov - Web page: https://patentgrep.com/patent/US9437412B2 ## CPC - H01J 49/282: {using electrostatic analysers} - H01J 49/0009: {Calibration of the apparatus} - H01J 49/0031: {Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence)} - H01J 49/22: Electrostatic deflection - H01J 49/424: {Three-dimensional ion traps, i.e. comprising end-cap and ring electrodes} - H01J 49/425: {with a logarithmic radial electric potential, e.g. orbitraps} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract This invention relates generally to multi-reflection electrostatic systems, and more particularly to improvements in and relating to the Orbitrap electrostatic ion trap. A method of operating an electrostatic ion trapping device having an array of electrodes operable to mimic a single electrode is proposed, the method comprising determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode, and applying the three or more so determined voltages to the respective electrodes. Further improvements lie in measuring a plurality of features from peaks with different intensities from one or more collected mass spectra to derive characteristics, and using the measured characteristics to improve the voltages to be applied to the plurality of electrodes. ## Claims ### Claim 1 A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising: providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, at least one of the inner electrode or the outer electrode comprise an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the array of electrodes including elements of the outer electrode but not elements of the inner electrode or the array of electrodes including elements of the inner electrode but not the outer electrode; applying voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ions. ### Claim 2 (depends on 1) The method of claim 1, wherein the outer electrode is divided into at least four electrodes of the array. ### Claim 3 (depends on 2) The method of claim 2, wherein the electrodes of the array form at least one pair of detection electrodes, each pair of detection electrodes comprising first and second longitudinally spaced apart detection electrodes. ### Claim 4 A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising: providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, the outer electrode divided into at least four electrodes of an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the inner diameters of the at least four electrodes of the array are substantially uniform; applying voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ions. ### Claim 5 (depends on 2) The method of claim 2, wherein the inner diameters of the electrodes of the array are selected to approximate an equipotential line of a hyper-logarithmic field. ### Claim 6 (depends on 1) The method of claim 1, wherein the inner electrode is divided into a plurality of electrodes of the array. ### Claim 7 (depends on 6) The method of claim 6, wherein the outer diameters of the electrodes of the array are selected to approximate an equipotential line of a hyper-logarithmic field. ### Claim 8 (depends on 1) The method of claim 1, wherein the trapping field approximates a hyper-logarithmic field. ### Claim 9 (depends on 1) The method of claim 1, further comprising introducing the ions into the trapping volume. ### Claim 10 (depends on 1) The method of claim 1, wherein the array of electrodes including elements of the outer electrode but not elements of the inner electrode and a second array of electrodes includes elements of the inner electrode but not elements of the outer electrode. ### Claim 11 A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising: providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, the inner electrode divided into a plurality of electrodes of an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the outer diameters of the plurality of electrodes of the array are substantially uniform applying, voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ion.