Dynamic Oscillating Field for Time of Flight Mass Analyzer Aberration Correction
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Solution Overview
Problem
Time of Flight mass analyzers face limitations in resolving power due to second and higher order spatial focusing aberrations, particularly the 'turn around time' caused by initial velocity spread, which is challenging to minimize without compromising other performance aspects like flight time and sensitivity.
Innovation Solution
A supplemental time varying, oscillating electric field is applied to the acceleration electrodes to create a homogeneous electric field, correcting second order spatial focusing aberrations and maintaining a high field pusher voltage, allowing for improved resolution without increasing flight time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the acceleration field is made steeper by maximizing the electric field ratio Vp/Lp, then the turn around time aberration is reduced, but the flight time becomes very short requiring ultra fast high bandwidth detection systems
Solution Approach 1:
The patent applies a time-varying oscillating voltage to the acceleration electrode rather than a static DC voltage. This dynamic approach allows the electric field to change over time, creating a homogenous field that reduces second order spatial focusing aberrations while maintaining practical flight times. The oscillating field adapts to the ion packet's position and velocity distribution during acceleration.
Solution Approach 2:
The patent changes the parameter of the acceleration field from a static DC voltage to a time-varying oscillating voltage with specific frequency and amplitude characteristics. This parameter change enables the field to maintain homogeneity throughout the acceleration process, correcting spatial focusing aberrations without requiring extremely steep field gradients that would reduce flight time.
2Measurement precision
If second and higher order spatial focusing aberrations are corrected by optimizing geometry and field amplitudes, then resolving power is improved, but the instrument design becomes more complex with limited geometries
Solution Approach 1:
The patent uses parameter changes by applying a time-varying oscillating voltage to correct second order spatial focusing aberrations. This approach provides an additional degree of freedom in controlling ion dynamics without requiring complex geometric arrangements. The oscillating field parameters (frequency, amplitude, phase) can be adjusted to optimize focusing for different mass ranges.
Solution Approach 2:
By using a dynamic oscillating field rather than static field geometries, the patent achieves aberration correction through temporal variation of the field parameters. This dynamic approach simplifies the spatial geometry requirements while maintaining high resolving power across different mass to charge ratios.
3Loss of time
If a high field pusher voltage is applied to accelerate ions forcefully, then the turn around time is minimized, but second order spatial focusing aberrations increase
Solution Approach 1:
The patent applies a time-varying oscillating voltage that dynamically adjusts the field strength during the ion acceleration process. This allows the field to provide strong initial acceleration to minimize turn around time while subsequently adjusting to create a homogenous field that corrects second order spatial focusing aberrations, achieving both goals simultaneously.
Solution Approach 2:
The oscillating voltage applied to the acceleration electrode creates a periodic electric field that cycles through different field strengths and directions. This periodic action allows the field to first provide strong acceleration and then create homogeneity conditions, correcting aberrations through the temporal variation rather than requiring a static optimized geometry.
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 enhances the resolving power of Time of Flight mass analyzers by reducing second order spatial focusing aberrations, enabling higher resolution at low mass to charge ratios and expanding the range of geometries usable in instrument design.
Implementation Method 1
A supplemental time varying, oscillating electric field is applied to the acceleration electrodes to create a homogeneous electric field
Implementation Method 2
The DC voltage pulse which is applied to the pusher electrode generates a DC electric field which causes ions to be orthogonally accelerated
Data Source
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AI summary
A Time of Flight mass analyser is disclosed comprising one or more acceleration electrodes and a first device arranged and adapted to apply a DC voltage pulse to the one or more acceleration electrodes. The DC voltage pulse causes ions to be accelerated into a time of flight or drift region and the DC voltage pulse is applied, in use, to the one or more acceleration electrodes between a time Ti and a time T2. A second device is arranged and adapted to apply a single phase oscillating voltage to the one or more acceleration electrodes, wherein the single phase oscillating voltage undergoes multiple oscillations between the time T1 and the time T2. The application of the DC voltage pulse and the single phase oscillating voltage to the one or more acceleration electrodes establishes an homogeneous electric field having a net force towards the time of flight or drift region.