3D RF Ion Trap Ejection via End Cap Voltage Switching
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Solution Overview
Problem
The challenge lies in collectively ejecting ions from three-dimensional Paul RF ion traps without disrupting their operation as high-quality mass analyzers, particularly when transferring ions to Kingdon ion traps, due to the difficulty in abruptly switching off the RF voltage used for storage, which is essential for maintaining high mass resolution.
Innovation Solution
The method involves replacing the RF voltage at the ring electrode with a more rapidly switchable RF voltage applied to the end cap electrodes, allowing for the ions to be stored and then ejected using a DC voltage, thereby avoiding the need to abruptly switch off the high-quality resonant circuit at the ring electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RF voltage is used at the ring electrode for ion storage, then mass resolution is improved, but the ability to rapidly switch off the voltage for collective ejection deteriorates
Solution Approach 1:
The patent divides the ion trap electrode system into functionally independent segments: the ring electrode maintains continuous RF voltage for mass analysis, while the end cap electrodes can be independently switched for ejection. This segmentation allows each electrode to perform its specialized function without compromising the other.
Solution Approach 2:
The end cap electrodes serve as intermediary elements that mediate between the continuous RF field required for mass resolution and the abrupt voltage switching needed for ejection. By applying RF voltage to the end caps rather than the ring electrode during ejection, the system achieves rapid switching while preserving the ring electrode's mass analysis function.
2Speed
If RF voltage is abruptly switched off for collective ejection, then ejection speed is improved, but mass resolution deteriorates
Solution Approach 1:
Before collective ejection, the system preliminarily switches from ring electrode RF voltage to end cap electrode RF voltage. This preliminary action prepares the ion cloud for ejection by applying voltage to the electrodes that will control the ejection process, enabling rapid switching without disrupting the ring electrode's mass analysis function.
Solution Approach 2:
The patent extracts the ejection function from the ring electrode's continuous RF voltage by applying RF voltage specifically to the end cap electrodes. This separation allows the ejection operation to be performed independently without affecting the mass resolution provided by the ring electrode's ongoing RF field.
3Adaptability or versatility
If RF voltage is used for ion storage, then ion manipulation capability is improved, but the ability to transfer ions to other mass analyzers deteriorates
Solution Approach 1:
The system dynamically switches between different voltage configurations: continuous RF at the ring electrode for ion storage and manipulation, and rapidly switchable RF at the end caps for ejection and transfer. This dynamic adaptability allows the same physical system to efficiently perform both ion manipulation and ion transfer functions.
Solution Approach 2:
The end cap electrodes serve multiple functions: they participate in ion trapping during normal operation, enable rapid ejection when needed, and facilitate transfer to other mass analyzers. This multi-functionality resolves the contradiction between maintaining ion manipulation capability and enabling efficient ion transfer.
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 enables efficient and controlled ejection of ions from the 3D RF ion trap, allowing for their transfer to high-resolution mass analyzers like Kingdon ion traps with minimal disruption to the ion trap's operation, achieving improved mass resolution and ion manipulation capabilities.
Implementation Method 1
They form a quadrupole pseudopotential well inside the ion trap, with a quadratic increase of the pseudopotentials extending uniformly from the center of the ion trap in all three dimensional directions
Implementation Method 2
The ion traps are usually operated with a damping gas at a pressure of 0.1 to 1.0 pascal in order to damp ('cool') the ion oscillations in the pseudopotential well of the ion trap
Implementation Method 3
a DC voltage is applied to at least one of the end cap electrodes to eject the ions through an opening in one of the end caps
Data Source
AI summary
The invention proposes a method for the collective ejection of ions from a 3D RF ion trap with a ring electrode and two end cap electrodes, which comprises the following steps: (a) the RF voltage of a high-quality resonant circuit applied to the ring electrode is replaced with a second RF voltage at the two end cap electrodes which can be changed or switched faster than the high voltage at the ring electrode, keeping the ions stored, (b) the second RF voltage at the end cap electrodes is then switched down or off abruptly, releasing the ions, and (c) the released ions are ejected through an opening in one of the end cap electrodes by switching on a DC voltage on at least one of the end cap electrodes.