Tapered Multipole Ion Guide for Mass Spectrometer Sensitivity
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Solution Overview
Problem
Mass spectrometers face ion loss and reduced sensitivity due to inefficient ion transport and gas flow handling in ion guides, particularly at higher gas flows, which can overwhelm existing ion guides and lead to ion destruction.
Innovation Solution
The use of multipole ion guides with elongated electrodes and a power supply for RF voltage, combined with gas dynamic ion transfer devices and planar RF ion guides, to confine and focus ions effectively, even at higher gas flows, by maintaining consistent gap and electrode shape along the ion guide and applying RF and DC voltages to manage gas drag and ion confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas flow is increased to bring more ions, then ion source productivity is improved, but ion guide reliability deteriorates due to overwhelming gas flow
Solution Approach 1:
The ion guide is divided into multiple sections with different cross-sectional areas. The entrance cross-section is larger to accept high gas flow and ions, while the exit cross-section is smaller to match the mass analyzer aperture. This segmentation allows the ion guide to handle high gas flows without overwhelming the system while maintaining reliable ion transport.
Solution Approach 2:
Different sections of the ion guide have different geometric properties tailored to local requirements. The entrance region has a larger cross-section to accommodate high gas flow, while the exit region has a smaller cross-section for efficient ion transmission to the mass analyzer. This local optimization resolves the contradiction between handling high gas flow and maintaining ion guide reliability.
2Productivity
If ion guide cross-section is reduced to improve ion focusing, then ion transport efficiency is improved, but gas flow handling capacity deteriorates
Solution Approach 1:
The ion guide cross-section is segmented along its length, with the entrance having a larger area to handle high gas flow and the exit having a smaller area for efficient ion focusing. This segmentation allows the system to simultaneously achieve high gas flow handling capacity and high ion transport efficiency.
Solution Approach 2:
The ion guide transitions from a two-dimensional cross-sectional view to a three-dimensional tapered structure. By varying the cross-sectional area along the length of the ion guide, the system can accommodate high gas flow at the entrance while achieving tight ion focusing at the exit, resolving the contradiction between gas flow handling and ion transport efficiency.
3Productivity
If inlet aperture is increased to allow more ions, then ion transmission is improved, but gas flow into vacuum chamber increases causing ion loss
Solution Approach 1:
The inlet aperture system is segmented into multiple small apertures arranged in an array rather than a single large aperture. This segmentation allows the total ion transmission area to be increased while each individual aperture maintains proper gas flow characteristics, preventing ion loss due to excessive gas flow into the vacuum chamber.
Solution Approach 2:
The inlet aperture configuration transitions from a single aperture to a two-dimensional array of multiple apertures. This dimensional change increases the total effective area for ion transmission while maintaining the gas flow handling capabilities of individual small apertures, thereby improving ion transmission without causing ion loss.
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 ion transport efficiency, reduces losses, and increases sensitivity by effectively handling higher gas flows and focusing ions, ensuring reliable ion transmission to subsequent mass analysis stages.
Implementation Method 1
confining the ions in the vicinity of the gap by a combination of the gas drag due to transverse velocity of the gas and the RF voltage
Implementation Method 2
a radio frequency voltage can be applied to the ion guide to provide radial focusing of ions within the ion guide
Implementation Method 3
The ion guide transports and focuses ions from the ion source into a subsequent vacuum chamber
Implementation Method 4
provide radial focusing of ions within the ion guide
Implementation Method 5
the ions are entrained in a gas flow, the gas flow having a longitudinal velocity and a transverse velocity
Data Source
AI summary
An ion source and an ion guide chamber are provided. The ion guide chamber having a gas flow, the gas flow having a longitudinal velocity and a transverse velocity. The ion guide chamber having an exit aperture and at least one ion guide. The at least one ion guide having an entrance end and an exit end with an exit cross-section wherein the exit cross-section is sized to be smaller in area than the entrance cross-section. The at least one ion guide having a plurality of elongated electrodes wherein a gap between the elongated electrodes and the shape of the elongated electrodes in the vicinity of the gap are essentially the same along the length of the at least one ion guide for confining the ions in the vicinity of the gap by a combination of the transverse velocity of the gas and the RF voltage.