Ion-Optical Lens Time-Varying Potential Control
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Solution Overview
Problem
Current ion trapping devices face challenges in efficiently trapping ions from laser desorption/ionization sources due to wide initial velocity and kinetic energy spreads, particularly for higher mass-to-charge ratios, leading to reduced trapping efficiency and sensitivity.
Innovation Solution
The use of time-varying electrical potentials in ion-optical lenses to control the kinetic energy of ions as a function of mass-to-charge ratio, allowing for progressive acceleration or deceleration across the entire mass range, thereby optimizing the phase space distribution and enhancing injection efficiency and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ions are directly injected from MALDI source into ion trap, then the simplicity of the system is maintained, but trapping efficiency is reduced due to wide initial velocity spread and high kinetic energy
Solution Approach 1:
An ion-optical lens system is introduced as an intermediary device between the MALDI source and ion trap. This lens system includes multiple electrodes that generate electrostatic fields to decelerate, focus, and control the phase space distribution of ions before they enter the ion trap, thereby improving trapping efficiency without significantly complicating the overall system architecture
Solution Approach 2:
The patent applies time-varying electrical potentials to the lens electrodes to dynamically control ion kinetic energy and angular divergence. By adjusting voltage parameters in real-time during ion injection, the system optimizes phase space distribution for different mass-to-charge ratios, significantly improving trapping efficiency across a wide mass range
2Device complexity
If electrostatic fields are used for ion transport, then the mass range injected is limited, but the device complexity is reduced
Solution Approach 1:
The patent transforms static electrostatic fields into dynamic, time-varying electrostatic fields by applying modulated voltages to the lens electrodes. This dynamic control allows the lens system to adapt to ions of different masses and kinetic energies, extending the injectable mass range while maintaining a relatively simple device structure without requiring multiple fixed-field stages
3Reliability
If time-varying potentials are applied to lens electrodes, then ion trapping efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent employs periodic or pulsed voltage applications to the lens electrodes, synchronized with the ion extraction timing from the MALDI source. This periodic control scheme simplifies the complexity management by using repetitive voltage patterns rather than completely arbitrary waveforms, while still achieving optimal phase space distribution and trapping efficiency
Solution Approach 2:
The lens system performs preliminary deceleration and focusing of ions before they enter the ion trap. By pre-conditioning the ion beam with appropriate voltage sequences, the system reduces the complexity of subsequent trapping operations and maximizes injection efficiency in a single controlled stage
4Ease of operation
If ions with wide kinetic energy spread are injected, then the sensitivity is reduced, but the ease of operation is maintained
Solution Approach 1:
The patent applies different voltage potentials to different electrodes within the lens system to create localized electric field regions with specific functions: one region for deceleration, another for focusing, and another for angular divergence control. This localized control of ion properties improves sensitivity by addressing specific aspects of ion beam quality independently, while maintaining overall operational simplicity through a unified control interface
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 approach extends the mass range that can be trapped and improves sensitivity by controlling the kinetic energy and angular divergence of the ion beam, enabling more efficient trapping of ions across a wider mass range and reducing focal length dispersion.
Implementation Method 1
a first electrical potential is established throughout a first region of the ion-optical lens bridging the first and second lens electrodes and a second electrical potential is established throughout a second region of the ion-optical lens bridging the second and third lens electrodes
Implementation Method 2
a time-varying electrical potential difference is produced between the first and second lens electrodes which establishes a time-varying axial potential gradient (electric field E, volts/metre) able to apply a force to accelerate or decelerate ions traversing along the optical axis
Data Source
Figure 1~2(c)
Figure 3(a)~3(c)
Figure 4(a)~4(d)
AI summary
A mass spectrometer comprises ion pulse means for producing ion pulses in a first vacuum chamber, ion trap means for receiving and trapping the ion pulses for mass analysis in a second vacuum chamber, and ion-optical lens means arranged between the ion pulse means and the ion trap means for receiving the ion pulses and outputting ions therefrom to the ion trap means. A first lens electrode and a second lens electrode collectively define an optical axis and are adapted for distributing a first electrical potential and second electrical potential therealong. Lens control means vary non-periodically with time the first electrical potential relative to the second electrical potential to control as a function of ion mass-to-charge ratio the kinetic energy of ions which have traversed the ion optical lens means. This controls the mass range of the ions receivable by the ion trap from the ion optical lens means.