Electrostatic Mass Spectrometer with Encoded Pulses
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Solution Overview
Problem
Existing electrostatic mass spectrometers face limitations in sensitivity, speed, dynamic range, and ion throughput, particularly with modern ion sources generating high ion flows, which degrades analyzer parameters and results in low duty cycle and noise in recovered spectra.
Innovation Solution
Implementing a method with fast pulsing of an ion source or pulsed converter using unique time intervals between pulses, acquiring long spectra, and decoding using logical analysis of peak overlaps to avoid systematic overlaps and enhance signal summation, specifically employing non-periodic pulses to improve mass resolution and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion accumulation and pulsed release from linear ion guide is used to improve OA duty cycle, then duty cycle increases, but mass range is restricted and detecting system saturates
Solution Approach 1:
The patent employs periodic orthogonal acceleration pulses to continuously sample ions from the ion source, creating a duty cycle接近100% by alternating between acceleration and non-acceleration phases. This periodic action allows the system to handle high ion flows without saturation while maintaining broad mass range capability through the continuous sampling nature of the orthogonal acceleration scheme.
2Productivity
If ion velocity modulation within RF ion guide is used to improve OA duty cycle, then duty cycle increases, but ion packets expand due to self space charge
Solution Approach 1:
The patent replaces velocity modulation mechanisms with direct spatial and temporal focusing using electrostatic fields in the orthogonal accelerator. By substituting the mechanical/field-based velocity modulation with electric field-based direct acceleration and focusing, the system achieves high duty cycle while maintaining tight ion packet confinement without self-space-charge expansion.
Solution Approach 2:
The patent changes the timing and spatial parameters of ion acceleration by using short, precisely timed orthogonal acceleration pulses. By adjusting the pulse width, repetition frequency, and acceleration voltage, the system optimizes both duty cycle and ion packet confinement, transforming the parameter space to achieve high productivity without sacrificing precision.
3Productivity
If frequent orthogonal acceleration pulsing is used to improve sensitivity and speed, then sensitivity and speed increase, but noise increases in recovered spectra
Solution Approach 1:
The patent implements feedback through synchronized detection and computational reconstruction algorithms that correlate ion arrival times with the known orthogonal acceleration pulse sequence. This feedback mechanism allows the system to distinguish true signal from noise by comparing detected arrivals against expected arrivals based on the encoded pulse timing, thereby improving signal-to-noise ratio while maintaining high sensitivity and speed.
Solution Approach 2:
The patent uses temporal encoding analogous to color coding, where different orthogonal acceleration pulse patterns create distinct temporal signatures for different ion packets. By encoding the pulse sequence with unique time intervals and using computational decoding, the system can differentiate overlapping signals and reduce noise in the recovered spectra, similar to how color changes enable differentiation in visual systems.
4Loss of information
If Hadamard Transformation with frequent orthogonal acceleration pulses is used, then spectra recovery is achieved, but additional noise originates from reverse HT due to variations in ion source flux and detector response
Solution Approach 1:
The patent creates multiple copies of the ion signal through repeated orthogonal acceleration cycles with encoded pulse patterns. By acquiring multiple spectra copies under different pulse conditions and using computational reconstruction, the system recovers the complete mass spectrum while averaging out random noise and compensating for variations in ion source flux and detector response, thereby reducing the noise introduced by reverse transformation.
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 significantly enhances sensitivity, speed, and dynamic range of electrostatic mass spectrometers, allowing for higher ion throughput and accurate spectral decoding, even with sparse and low-intensity spectra, while maintaining sharp resonance for correct mass hypotheses.
Implementation Method 1
A pulsed ion source for ion packet formation
Implementation Method 2
An electrostatic mass spectrometer providing an ion packet passage though the analyzer in a Z-direction and isochronous ion oscillations in an orthogonal direction
Implementation Method 3
An ion detector
Data Source
AI summary
A method, apparatus and algorithms are disclosed for operating an open electrostatic trap (E-trap) or a multi-pass TOF mass spectrometer with an extended flight path. A string of start pulses with non equal time intervals is employed for triggering ion packet injection into the analyzer, a long spectrum is acquired to accept ions from the entire string and a true spectrum is reconstructed by eliminating or accounting overlapping signals at the data analysis stage while using logical analysis of peak groups. The method is particularly useful for tandem mass spectrometry wherein spectra are sparse. The method improves the duty cycle, the dynamic range and the space charge throughput of the analyzer and of the detector, so as the response time of the E-trap analyzer. It allows flight extension without degrading E-trap sensitivity.