Ion Pulse Frequency Measurement Without Dead Time
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Solution Overview
Problem
Existing mass spectrometry techniques face inefficiencies in determining the average frequency of ion detection pulses due to dead time and wasted measurement intervals, particularly when multiple ion detectors with varying pulse frequencies are used in parallel.
Innovation Solution
A method that calculates the average frequency by using an auxiliary interval overlapping the measurement interval, starting at the last pulse preceding the measurement interval and ending at the last pulse of the measurement interval, thereby avoiding dead times and utilizing the entire measurement time effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If integration time begins at the first pulse during the measurement interval, then the measurement can be synchronized with pulse occurrence, but part of the measurement interval is effectively not used causing dead time
Solution Approach 1:
The integration period is extended backwards to start at a predetermined time point before the first pulse occurrence. This preliminary extension allows the measurement to capture all pulses within the measurement interval without waiting for the first pulse, thereby eliminating the dead time at the beginning of the measurement interval while maintaining synchronization capability.
2Duration of action of moving object
If the integration period ends at the first pulse after a minimum duration, then a fixed measurement duration is ensured, but the end of the measurement interval is not fully utilized
Solution Approach 1:
The integration period is extended beyond the last pulse occurrence to reach the end of the measurement interval. This extension ensures that the full measurement interval duration is utilized for measurement purposes, converting what would otherwise be wasted time into productive measurement time while maintaining the required minimum integration duration.
3Productivity
If multiple ion detectors with varying pulse frequencies are used in parallel, then detection capability is improved, but measurement coordination becomes complex causing accuracy loss
Solution Approach 1:
A universal measurement interval and integration period framework is established that works for all ion detectors regardless of their individual pulse frequencies. The integration period is defined by fixed time points relative to the measurement interval boundaries rather than being dependent on specific pulse occurrences, making the measurement system universally applicable to detectors with varying pulse rates while maintaining coordination and accuracy.
Data Source
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AI summary
A method and device for determining an average frequency of a series of ion detection pulses (P) in a spectrometer can be applied to a measurement interval (MI). The method may comprise determining the duration of an auxiliary interval (AI1, AI2, ...), wherein the auxiliary interval overlaps the measurement interval, the auxiliary interval starts at the last pulse (P0) preceding the measurement interval (MI), and the auxiliary interval ends at the last pulse (PN) within the measurement interval. The method may further comprise determining the number of pulses during the auxiliary interval and dividing the number of pulses by the duration of the auxiliary interval so as to produce the average frequency. The method may be applied to a series of ion pulses produced by a voltage-to-frequency converter connected to a Faraday cup.