Electrostatic Lens Asymmetric Electrode Configuration Ion Beam Filtering
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Solution Overview
Problem
Existing technologies face challenges in effectively removing undesirable background particles from ion beams in mass spectrometry and focused ion beam applications, leading to reduced analytical performance and signal noise due to the transmission of energetic charged and uncharged particles, which interfere with the detection of desired ions.
Innovation Solution
The use of electrostatic lenses configured with multiple electrodes and a potential generator to direct and focus charged particles within a specific kinetic energy range, while blocking particles outside this range, thereby improving ion transmission efficiency and reducing background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If kinetic energy filters are used to pass charged particles with narrow energy range, then transmission precision of desired ions is improved, but transmission efficiency of ions is reduced
Solution Approach 1:
The electrostatic lens is divided into multiple electrodes (first electrode with entrance aperture, second electrode with exit aperture, and intermediate electrodes) that can be independently controlled. This segmentation allows different regions of the lens to perform different functions: focusing ions while simultaneously filtering by energy, thereby resolving the contradiction between precision and efficiency
Solution Approach 2:
The lens operates by changing electric field parameters (voltages applied to different electrodes) to create specific field configurations that focus ions of desired energy while deflecting ions of unwanted energy. By dynamically adjusting electrode potentials, the system optimizes both transmission efficiency and energy selection precision
2Manufacturing precision
If electrostatic fields are used to focus ion beams, then focusing capability is improved, but transmission of undesirable particles with different energies is not effectively blocked
Solution Approach 1:
The electrostatic lens employs asymmetric electrode configurations and non-uniform electric field distributions that create energy-dependent focusing. Ions with specific energies follow focused trajectories through the asymmetric field, while ions with different energies (undesirable particles) follow divergent paths and are blocked, thus achieving both focusing precision and background particle rejection
3Ease of operation
If RF ion guides are used to transport ions through vacuum regions, then ion transport is achieved, but collisional losses and scattering occur at interfaces between high and low vacuum regions
Solution Approach 1:
The electrostatic lens acts as an intermediary device between RF ion guide regions of different vacuum pressures. It provides a transition zone with controlled electric fields that guide ions smoothly from high vacuum to low vacuum regions, minimizing abrupt changes that cause scattering and collisional losses, thereby improving transmission stability while maintaining transport capability
4Quantity of substance
If background particles are transmitted along with ion beams, then particle flux is maintained, but background noise at detector increases and analytical sensitivity decreases
Solution Approach 1:
The electrostatic lens converts the harmful effect of background particles into a beneficial filtering mechanism. By designing the electric field configuration to be energy-selective, the lens allows desired ions to pass while using the different energy characteristics of background particles to deflect and block them. This transforms the particle flux maintenance function into a dual function of flux control and noise reduction, improving signal to noise ratio while maintaining adequate particle flux
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 analytical sensitivity by minimizing background noise and preventing the transmission of undesirable particles, resulting in improved focusing and transmission efficiency of ion beams, even in low vacuum regions, and reduces the buildup of contaminants that cause charging effects.
Implementation Method 1
electrostatic lenses can be configured according to the invention to reduce or remove undesirable background particles from an ion beam
Implementation Method 2
electrostatic lenses can focus or otherwise re-direct the trajectories of ions with electrostatic fields
Data Source
AI summary
A system includes an electrostatic lens in a path between a charged particle source and a detector. The electrostatic lens includes: a first electrode having a first aperture in the path aligned with a first axis; a second electrode in the path between the first electrode and the detector, having a second aperture in the path and aligned with a second axis that is parallel to the first axis and displaced from the first axis along a first direction; a third electrode in the path between the first electrode and the second electrode; and a potential generator coupled to the electrodes. During operation, the potential generator applies potentials to the first, second and third electrodes so that the electrostatic lens directs a beam of charged particles from the source propagating along the first axis to propagate along the second axis.