Ion Trap End Cap Voltage Control via Capacitive Division
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Solution Overview
Problem
Existing ion trap mass spectrometers face challenges in achieving optimal performance and spectral resolution due to the complexity and power consumption associated with applying additional signals to end caps, which can result in double peaks and increased system size and weight.
Innovation Solution
A conductive ring-shaped central electrode with passive electrical components, such as capacitors and resistors, is used to derive an excitation voltage for the end caps, allowing for improved axial excitation without additional signal generators, reducing power consumption and complexity, and eliminating double peaks in the output spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional signal is applied to one end cap of the ion trap to improve performance and eliminate double peaks, then spectral resolution is improved, but device complexity and power consumption increase due to requiring additional signal generators and electronics
Solution Approach 1:
The single signal source is designed to perform multiple functions: it generates both the center electrode signal and the end cap signal through its output terminals. The signal source couples to the center electrode through a coupling capacitor and to the end cap through a voltage divider network, allowing one device to control multiple trap electrodes simultaneously, thereby reducing overall system complexity while maintaining spectral resolution improvements
Solution Approach 2:
The patent combines the signal generation for both the center electrode and end cap into a single signal source rather than using separate signal generators. The output of this single signal source is split through passive components (capacitors and resistors) to drive both electrodes, merging the signal generation function into one unit and eliminating the need for additional electronics
2Measurement precision
If an additional signal is applied to one end cap of the ion trap to improve performance and eliminate double peaks, then spectral resolution is improved, but power consumption increases due to additional electronics and signal generation
Solution Approach 1:
The single signal source performs dual functionality by providing signals to both the center electrode and end cap simultaneously. This eliminates the need for a second signal generator and its associated power consumption, while still achieving the spectral resolution benefits of end cap signaling through the voltage divider network
Solution Approach 2:
The end cap signal is created as a derived copy of the center electrode signal through the voltage divider network formed by capacitors and resistors. Rather than generating an independent signal, the system creates a scaled version of the original signal, reducing power requirements while maintaining the functional benefit of differential end cap control
3Reliability
If differential voltages are applied to end caps to achieve resonance ejection at lower voltages, then ion trap performance is improved, but the requirement for multiple voltage supplies increases device complexity
Solution Approach 1:
The single signal source is configured to provide differential voltages to the end caps relative to the center electrode through its coupling capacitors and the voltage divider network. This allows the ion trap to achieve resonance ejection at lower voltages with improved performance while using only one voltage supply, eliminating the complexity of multiple voltage sources
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 spectral resolution and ion trap performance with minimal added complexity, cost, or power consumption, allowing for improved mass spectrometric chemical analysis without the need for additional electronics.
Implementation Method 1
An ion trap internally traps ions in a dynamic quadrupole field created by the electrical signal applied to the center electrode relative to the end cap voltages (or signals)
Implementation Method 2
This second signal causes an axial excitation that results in the resonance ejection of ions from the ion trap when the ions' secular frequency of oscillation within the trap matches the end cap excitation frequency
Implementation Method 3
A first intrinsic capacitance is formed between a surface of the first electrode end cap and a surface of the first open end of the central electrode. A second intrinsic capacitance is formed between a surface of the second electrode end cap and a surface of the second open end of the central electrode
Data Source
AI summary
An ion trap for a mass spectrometer has a conductive central electrode with an aperture extending from a first open end to a second open end. A conductive first electrode end cap is disposed proximate to the first open end thereby forming a first intrinsic capacitance between the first end cap and the central electrode. A conductive second electrode end cap is disposed proximate to the second open end thereby forming a second intrinsic capacitance between the second end cap and the central electrode. A first circuit couples the second end cap to a reference potential. A signal source generating an AC trap signal is coupled to the central electrode. An excitation signal is impressed on the second end cap in response to a voltage division of the trap signal by the first intrinsic capacitance and the first circuit.