Elongated Transparent Orthogonal Accelerator for Mass Spectrometer Duty Cycle
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Solution Overview
Problem
The duty cycle of time-of-flight mass spectrometers is limited by the geometrical arrangement of orthogonal accelerators, leading to inefficiencies in pulsed conversion and spectral overlaps, particularly in multi-pass instruments where the resolution is compromised by the need to keep the orthogonal accelerator short to avoid ion packet length limitations.
Innovation Solution
The orthogonal accelerator is elongated in the drift direction and made transparent using slits or meshes, allowing ions to pass through without hitting the electrodes, enabling longer ion packet lengths and increased duty cycle without compromising spectral resolution or admitted mass range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the orthogonal accelerator is made short to avoid ion packet length limitations, then spectral resolution is maintained, but duty cycle is limited and pulsed conversion efficiency is reduced
Solution Approach 1:
The patent introduces a temporal dimension to the problem by implementing multi-pass ion reflection. Instead of extending the accelerator in spatial dimension (which would cause spectral overlaps), ions are reflected multiple times between ion mirrors, allowing them to traverse the same accelerator length multiple times. This effectively increases the duty cycle without compromising spectral resolution, as each pass contributes to the overall ion detection while maintaining temporal separation of ion packets.
2Productivity
If the orthogonal accelerator length is increased to improve duty cycle, then pulsed conversion efficiency improves, but ion packet length limitations cause spectral overlaps
Solution Approach 1:
The patent implements periodic action through multi-pass ion reflection between ion mirrors. Ions are reflected back and forth through the orthogonal accelerator multiple times in a periodic manner, with each reflection allowing another ion packet to be injected. This periodic reuse of the accelerator space enables high duty cycle operation without increasing the physical accelerator length, thereby avoiding spectral overlaps while maintaining high pulsed conversion efficiency.
3Device complexity
If conventional orthogonal accelerator geometry is used, then device simplicity is maintained, but duty cycle is limited by geometrical arrangement
Solution Approach 1:
The patent makes the orthogonal accelerator universal by enabling it to serve multiple functions: it acts as both the ion acceleration region and the ion storage region through multi-pass reflection. The same accelerator structure is reused for multiple ion packets across multiple passes, eliminating the need for separate storage structures. This multi-functionality approach increases duty cycle without significantly increasing device complexity, as the existing accelerator components are utilized more efficiently.
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 improves the duty cycle and space charge capacity of multi-pass time-of-flight mass spectrometers by an order of magnitude, maintaining high resolution and allowing analysis of a wider mass range without introducing additional aberrations.
Implementation Method 1
Periodically, an electrical pulse is applied between plates. A portion of the continuous ion beam, located in the storage gap, is accelerated in an orthogonal X-direction, thus forming ribbon-shaped ion packets. Due to conservation of initial Z-velocity, the ion packets drift slowly in the Z-direction
Implementation Method 2
the ion packets drift slowly in the Z-direction, thus traveling within the TOF MS along an inclined mean ion trajectory, get reflected by ion mirror
Implementation Method 3
Ions are locked axially by various types of DC plugs, get dampened in gas collisions at gas pressures of about 1 to 10 mTorr
Implementation Method 4
Ions are admitted into a radio-frequency ion guide for radial confinement with RF fields
Data Source
AI summary
A multi-pass time-of-flight mass spectrometer is disclosed having an elongated orthogonal accelerator (30). The orthogonal accelerator (30) has electrodes (31) that are transparent to the ions so that ions that are reflected or turned back towards it are able to pass through the orthogonal accelerator (30). The electrodes (31) of the orthogonal accelerator (30) may be pulsed from ground potential in order to avoid the reflected or turned ion packets being defocused. The spectrometer has a high duty cycle and/or space charge capacity of pulsed conversion.