Linear Ion Trap Trigger Thresholds for Weak Ion Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrostatic linear ion traps face challenges in accurately distinguishing valid charge measurements from noise, especially at low charge levels, due to spurious charges picked up on the charge detector, limiting the range of detectable charge measurements.
Innovation Solution
The system modifies the charge detection threshold during trigger trapping operations in an electrostatic linear ion trap to facilitate the trapping of weakly-charged ions by using a comparator threshold that triggers on both low-amplitude charge signals and noise, allowing ions to oscillate back and forth through the charge detector for multiple measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high charge detection threshold is used to distinguish valid measurements from noise, then measurement reliability improves, but the ability to detect weakly-charged ions deteriorates
Solution Approach 1:
The charge detection threshold is made dynamic rather than fixed. The threshold automatically adjusts based on the detected charge signal amplitude - using lower thresholds for weakly-charged ions and higher thresholds for strongly-charged ions. This dynamic adaptation resolves the contradiction by allowing the system to maintain measurement reliability across the full range of charge magnitudes.
Solution Approach 2:
The detection threshold parameter is changed adaptively based on the ion's charge characteristics. By monitoring the charge signal and adjusting the threshold parameter accordingly, the system can detect both weakly-charged and strongly-charged ions with appropriate reliability for each charge level.
2Adaptability or versatility
If a low charge detection threshold is used to detect weakly-charged ions, then detectable charge range improves, but measurement reliability deteriorates due to noise interference
Solution Approach 1:
The threshold dynamically adapts to the signal characteristics, being low enough to capture weakly-charged ions but automatically raising when noise patterns are detected, thus maintaining reliability across the extended detection range.
Solution Approach 2:
The system uses feedback from the detected charge signals to continuously adjust the threshold. By analyzing the signal-to-noise ratio in real-time, the feedback mechanism ensures that the threshold remains appropriate for the current detection conditions, preventing false positives while capturing valid weak signals.
3Device complexity
If random trapping operation is used, then device simplicity is maintained, but trapping efficiency deteriorates
Solution Approach 1:
The ion trap system performs self-service by automatically detecting the arrival of an ion through the charge detector and autonomously switching from pass-through mode to trapping mode. This self-service mechanism dramatically improves trapping efficiency without requiring complex external control systems or manual intervention.
Solution Approach 2:
The charge detector provides feedback about ion presence to the control system, which then adjusts the mirror electrode voltages accordingly. This feedback loop enables the system to transition from simple random trapping to efficient triggered trapping, capturing ions with approximately 90% efficiency.
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 improves the probability of trapping ions, enhancing the accuracy and efficiency of charge and mass measurements, with trapping efficiency approaching 90% in optimized conditions compared to 37% with random trapping.
Implementation Method 1
a charge detector CD operable to detect a charge induced on the charge detection cylinder by the ion passing therethrough
Implementation Method 2
two ion mirrors M1, M2 respectively positioned at opposite ends of the charge detection cylinder CD... each defining a respective ion mirror region R1, R2 therein
Data Source
Figure 1
Figure 2A~2B
Figure 3~4C
AI summary
A system for trapping ions for measurement thereof may include an electrostatic linear ion trap (ELIT), a source of ions to supply ions to the ELIT, a processor operatively coupled to ELIT, and a memory having instructions stored therein executable by the processor to produce at least one control signal to open the ELIT to allow ions supplied by the source of ions to enter the ELIT, determine an ion inlet frequency corresponding to a frequency of ions flowing from the source of ions into the open ELIT, generate or receive a target ion charge value, determine an optimum threshold value as a function of the target ion charge value and the determined ion inlet frequency, and produce at least one control signal to close the ELIT when a charge of an ion within the ELIT exceeds the optimum threshold value to thereby trap the ion in the ELIT.