Multi-Pass TOF Ion Accelerator Layout for Higher Duty Cycle
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Solution Overview
Problem
Existing multi-pass time-of-flight mass spectrometers face limitations in duty cycle efficiency due to the inefficiencies of orthogonal accelerators, which affect resolution and spatial ion focusing, particularly when handling lighter ions.
Innovation Solution
The implementation of focusing electrodes that control ion motion in a second dimension orthogonal to the first, ensuring spatial focusing and uniform flight times, along with a pulsed ion accelerator that extends in the second dimension, allowing for longer ion packets and improved duty cycle without compromising resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If orthogonal accelerator is used for pulsed ion conversion, then ion packets can be formed and accelerated, but duty cycle efficiency is limited and resolution deteriorates
Solution Approach 1:
The patent introduces a second dimension (Y-direction) orthogonal to both the drift direction (Z) and acceleration direction (X). Focusing electrodes are positioned in this Y-dimension to control ion motion, enabling spatial focusing of ion packets without interfering with the primary acceleration and drift processes. This dimensional addition resolves the contradiction by providing a new control axis that improves duty cycle while maintaining resolution.
Solution Approach 2:
The patent modifies the electric field parameters by adding focusing electrodes that create additional electric field components in the Y-dimension. By adjusting the voltages on these focusing electrodes, the ion packet dynamics can be optimized to achieve both high duty cycle and high resolution simultaneously, changing the field configuration from simple orthogonal acceleration to a more complex multi-component field structure.
2Productivity
If orthogonal accelerator length is increased to improve duty cycle, then more ions can be processed, but spatial ion focusing deteriorates and resolution is compromised
Solution Approach 1:
By adding focusing electrodes in the Y-dimension, the patent enables control of ion packet spatial distribution without extending the Z-length of the orthogonal accelerator. The focusing electrodes create electric field gradients that compress and focus ion packets in the Y-direction, achieving improved spatial focusing and resolution while maintaining a compact accelerator structure and high duty cycle.
Solution Approach 2:
The focusing electrodes are positioned at specific locations within the orthogonal accelerator structure, creating localized regions of enhanced electric field that provide spatial focusing only where needed. This local intervention allows the majority of the accelerator to maintain its original design for high duty cycle operation, while specific zones provide the additional focusing function required for improved resolution.
3Productivity
If conventional orthogonal accelerator is used in multi-pass TOF, then ion packets can be accelerated, but duty cycle is limited to avoid spectral overlaps
Solution Approach 1:
The focusing electrodes in the Y-dimension provide an additional control mechanism for managing ion packet behavior in multi-pass TOF. By adjusting the Y-dimension focusing, ion packets can be better controlled to maintain separation between different mass-to-charge ratio packets, reducing spectral overlaps and enabling higher duty cycle operation without the complexity of sophisticated timing and positioning control systems.
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 by an order of magnitude, supports a wide mass range analysis, and maintains high resolution by ensuring uniform ion flight paths and reduced aberrations, particularly beneficial for multi-pass TOF mass spectrometers.
Implementation Method 1
A portion of continuous ion beam, in the storage gap, is accelerated in an orthogonal X-direction, thus forming ribbon-shaped ion packets
Implementation Method 2
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 3
get reflected by the ion mirror and finally reach a detector
Implementation Method 4
Multi-pass time-of-flight mass spectrometer
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.