Ion Trap RF Pre-Lens for Energy Distribution Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ion traps face challenges in ejecting ions with a wide energy distribution and poor collimation, which complicates downstream processes such as beam focusing and injection into collision cells or mass analyzers, due to varying RF phases and instantaneous voltages at the time of ejection.
Innovation Solution
The implementation of an ion trap with a plurality of trap electrodes generating a RF trapping field and a series of lenses positioned outside the trap to adjust the kinetic energy of ejected ions, ensuring focused and energy-synchronized ion ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ions are ejected from the ion trap using standard RF ejection methods, then ions can be mass-selectively ejected from the trap, but the ions exhibit a wide energy distribution and poor collimation due to varying RF phases at the time of ejection
Solution Approach 1:
The patent applies preliminary action by introducing an RF pre-lens before the main ejection aperture. This pre-lens pre-conditiones the ions by applying an RF voltage that begins to focus and energize the ions before they reach the ejection point. By performing this preparatory action upstream, the system reduces the final energy spread and improves collimation at the aperture without compromising the mass-selective ejection capability
Solution Approach 2:
The patent uses an RF pre-lens as an intermediary component between the ion trap interior and the ejection aperture. This intermediary element mediates the transition of ions from the trap environment to the ejection environment by gradually adjusting their energy and direction. The pre-lens acts as a buffer that smooths out the energy distribution before ions enter the final ejection stage, thereby reducing the harmful effects of phase variations
2Quantity of substance
If ions are ejected over a wide range of RF phases to maintain trapping efficiency, then more ions can be ejected, but the energy distribution of ejected ions becomes wider and collimation deteriorates
Solution Approach 1:
The RF pre-lens serves as an intermediary that decouples the relationship between ejection quantity and energy precision. By positioning the pre-lens upstream, it can process a broad phase range of ions simultaneously, conditioning them to have more uniform energies before they reach the ejection aperture. This allows the system to maintain high ion throughput while improving energy distribution
Solution Approach 2:
The ejection process is segmented into multiple stages: the RF pre-lens stage for initial conditioning and the main ejection aperture stage for final release. This segmentation allows different parts of the ejection process to optimize for different functions - the pre-lens optimizes for energy uniformity while the aperture optimizes for ion throughput, resolving the contradiction between quantity and precision
3Manufacturing precision
If ion optics lenses are added at the trap output to improve focusing, then ion collimation may be improved, but changes in divergence interact with the energy distribution and RF phase at ejection, complicating the system
Solution Approach 1:
The RF pre-lens performs preliminary focusing action before ions reach the trap output. By establishing initial focus upstream, the system reduces the burden on downstream optics. This preliminary action allows simpler downstream lenses to achieve the same overall collimation效果, thereby reducing overall system complexity while maintaining precision
Solution Approach 2:
The RF pre-lens acts as an intermediary that decouples the interaction between divergence changes and energy distribution. By conditioning ions upstream, it creates a more stable input for downstream optics, reducing the harmful interactions that would otherwise require complex compensation mechanisms
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 narrows the range of kinetic energies and improves ion collimation, facilitating more efficient ion focusing and energy adjustment, thereby enhancing the performance of downstream processes in mass spectrometry systems.
Implementation Method 1
a radio frequency (RF) voltage on the trap electrodes generates a time-varying electric field in the trap interior that confines ions
Implementation Method 2
a plurality of lenses serially positioned outside the trap interior proximate to the aperture and configured for adjusting a kinetic energy of ions ejected from the trap interior
Data Source
AI summary
An ion trap includes a trap exit at which an ion energy adjusting device is located. The adjusting device may be configured for focusing a beam of ions ejected from the trap, reducing the energy distribution of the ions, and/or reducing the average kinetic energy of the ions. The adjusting device may include lenses to which RF and/or DC voltages are applied.