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US 9,000,364 B2Granted
Electrostatic ion trap
AssigneeMKS Instruments, Inc.
InventorsAlexei Victorovich Ermakov, Barbara Jane Hinch
Life of this patent
Estimating the term…
Abstract
An electrostatic ion trap confines ions of different mass to charge ratios and kinetic energies within an anharmonic potential well. The ion trap is also provided with a small amplitude AC drive that excites confined ions. The mass dependent amplitudes of oscillation of the confined ions are increased as their energies increase, due to an autoresonance between the AC drive frequency and the natural oscillation frequencies of the ions, until the oscillation amplitudes of the ions exceed the physical dimensions of the trap, or the ions fragment or undergo any other physical or chemical transformation.
Claims43
An ion trap comprising:
- an electrode structure that produces electrostatic potentials that confine ions both axially and radially to trajectories at natural oscillation frequencies, the confining axial potential being anharmonic;
- an AC excitation source having an excitation frequency and connected to at least one electrode of the electrode structure;
- and
- a scan control that reduces a frequency difference between the AC excitation frequency and the natural oscillation frequencies of the ions to achieve autoresonance.
1 more element
An ion trap mass spectrometer comprising:
- a first mirror electrode structure and a second mirror electrode structure, and a central lens electrode plate having an applied bias voltage and having an axially located aperture, the electrodes adapted and arranged to produce electrostatic potentials that confine ions electrostatically both axially and radially to trajectories that run along an ion confinement axis, the ions having natural oscillation frequencies, the confining axial potential being anharmonic along the axis;
- an AC excitation source having an excitation frequency and connected to at least one electrode and having an amplitude that is at least three orders of magnitude smaller than the absolute magnitude of the bias voltage applied to the central lens electrode;
- a scan control system that reduces a frequency difference between the excitation frequency and the natural oscillation frequencies of the ions to achieve autoresonance;
- an ion source;
- and
- at least one ion detector.
3 more elements
An ion trap comprising:
- means for electrostatically trapping the ions both axially and radially within an anharmonic potential created by an electrode structure;
- means for applying an AC drive at a frequency other than the natural oscillation frequencies of the ions and with an amplitude larger than a threshold amplitude;
- means for changing the conditions of the trap to reduce the frequency difference between the drive frequency and the natural oscillation frequencies of the ions to mass selectively achieve autoresonance;
- and
- means for continuing to change the conditions of the trap while maintaining autoresonance, with energy being pumped from the AC drive to the ions.
2 more elements
An ion trap comprising:
- an electrode structure that produces electrostatic potentials that confine ions both axially and radially to trajectories at natural oscillation frequencies, the confining axial potential being anharmonic, and the electrode structure including a first opposed mirror electrode structure and a second opposed mirror electrode structure and a central lens electrode structure, each mirror electrode structure including at least one compensating electrode;
- and
- an AC excitation source having an excitation frequency and connected to at least one electrode of the electrode structure.
An ion trap comprising:
- an electrode structure, including first and second opposed mirror electrodes and a central lens therebetween, that produces electrostatic potentials that confine ions both axially and radially to trajectories at natural oscillation frequencies, the confining axial potential being anharmonic;
- and
- an AC excitation source connected to at least one electrode having an excitation frequency f that excites confined ions at a frequency of about at least one integral multiple of the natural oscillation frequencies of the ions.
A mass spectrometer comprising:
- an ion source;
- an ion trapping electrode structure, including first and second opposed mirror electrode structures and a central lens structure therebetween having an applied bias voltage and having an axially located aperture, said ion trapping electrode structure producing an electrostatic potential distribution that confines ions both axially and radially to trajectories about a confinement axis, said confined ions oscillating along said confinement axis with natural oscillation frequencies, the confining electrostatic potential distribution being anharmonic along said confinement axis;
- an AC source connected to at least one electrode, said AC source operating at a driving frequency f, and operating at an AC source amplitude, and driving confined autoresonant ions, thereby increasing the energies of said confined autoresonant ions;
- a scan controller that controls said applied bias voltage and said driving frequency f and said AC source amplitude;
- and
- an ion detector.
3 more elements
Dependencies are inferred from the claim text.