Orthogonal Accelerator Layout in Multi-Pass TOF for Duty Cycle
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Solution Overview
Problem
Existing multi-pass time-of-flight mass spectrometers face limitations in duty cycle and resolution due to the arrangement of orthogonal accelerators within the isochronous ion motion plane, which compromises the efficiency of pulsed conversion and spatial focusing of ion packets.
Innovation Solution
The orthogonal accelerator is elongated in the drift direction and displaced from the isochronous ion motion plane, with ion packets being deflected transversely to bypass the accelerator, and focused isochronously in the drift direction using trans-axial lenses or Fresnel lenses, while confined within RF or DC quadrupolar fields to improve duty cycle and space charge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the orthogonal accelerator is arranged within the isochronous ion motion plane, then the spatial focusing of ion packets is maintained, but the duty cycle and efficiency of pulsed conversion are compromised
Solution Approach 1:
The patent applies dimensionality change by displacing the orthogonal accelerator from the isochronous ion motion plane (2D arrangement) to a three-dimensional configuration where the accelerator is elongated in the drift direction and positioned at a different spatial location. This allows ion packets to bypass the accelerator in the transverse direction while maintaining spatial focusing through trans-axial lenses, thereby resolving the contradiction between maintaining focusing precision and improving duty cycle.
2Productivity
If the orthogonal accelerator length is increased to improve duty cycle, then more ions can be pulsed, but the resolution and spatial focusing deteriorate
Solution Approach 1:
The patent introduces trans-axial lenses as intermediary elements that perform the spatial focusing function separately from the orthogonal accelerator. This allows the accelerator to be elongated in the drift direction to increase duty cycle without compromising resolution, as the lenses compensate for any degradation in spatial focusing by providing independent focusing action in the transverse direction.
3Quantity of substance
If ions are confined within RF or DC quadrupolar fields to improve space charge capacity, then more ions can be stored, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using RF or DC quadrupolar fields that serve dual purposes: they confine ions to improve space charge capacity while also providing transverse focusing of the ion beam. This eliminates the need for separate focusing elements in some configurations, thereby reducing overall device complexity despite the addition of field confinement structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the duty cycle of multi-pass time-of-flight mass spectrometers by an order of magnitude, allowing for wider mass range analysis and improved resolution without affecting the resolution of the multi-pass TOF instruments.
Implementation Method 1
Periodically, an electrical pulse is applied between the plates. A portion of continuous ion beam, in the storage gap, is accelerated in an orthogonal X-direction
Implementation Method 2
get reflected by the ion mirror
Implementation Method 3
focusing electrodes arranged and configured to control the motion of ions in a second dimension (Z-dimension) orthogonal to the first dimension so as to spatially focus each of the ion packets
Implementation Method 4
focused isochronously in the drift direction using trans-axial lenses or Fresnel lenses
Implementation Method 5
confined within RF or DC quadrupolar fields
Data Source
AI summary
Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converters—either orthogonal accelerator or radially ejecting ion trap. The converter 35 is displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packets 38 are pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedge 68 or Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.