Ion Guide Chamber with External RF Electrodes
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Solution Overview
Problem
Existing ion guide chambers for mass spectrometry face challenges in efficiently transferring ions from high pressure to high vacuum environments while avoiding ion loss and electrode contamination, and are prone to discharges due to complex geometries and low breakdown voltages.
Innovation Solution
A mechanically simple ion guide chamber design with a resistive structure along its axis for ion transport and external RF electrodes for focusing, which minimizes contamination and discharge risks, allowing for efficient ion transfer and high sensitivity analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF electrodes are arranged within the vacuum chamber to focus ions, then ion transmission efficiency is improved, but electrode contamination and discharge risks increase
Solution Approach 1:
The RF electrodes are extracted from the vacuum chamber and positioned externally. The patent describes RF electrodes arranged outside the vacuum chamber that generate RF fields penetrating through the chamber walls to focus ions within the chamber, thereby eliminating direct contact between electrodes and vacuum environment, preventing contamination and discharge while maintaining ion focusing capability
Solution Approach 2:
The vacuum chamber walls serve as an intermediary medium that transmits the RF field from external electrodes to the ion path inside the chamber. The chamber material allows RF field penetration while maintaining vacuum isolation, enabling indirect electrode-chamber interaction that avoids contamination
2Manufacturing precision
If complex geometries are used in ion guide chambers to control ion paths, then ion focusing is improved, but breakdown voltages decrease leading to discharges
Solution Approach 1:
The patent replaces complex mechanical electrode geometries within the chamber with external RF electrodes that utilize electromagnetic field penetration. Instead of shaping electrodes inside the chamber to control ion paths, the system uses externally positioned RF electrodes whose fields penetrate the chamber walls, simplifying the mechanical structure while maintaining ion path control through field configuration
Solution Approach 2:
The invention changes the operational parameters by using RF fields at specific frequencies and amplitudes that can penetrate chamber walls effectively. By adjusting RF frequency and amplitude parameters, the system achieves ion focusing without requiring complex internal geometries that would lower breakdown voltages
3Stress or pressure
If ions are transferred through multiple differential pumping stages with orifices, then pressure gradient is improved, but ion loss increases
Solution Approach 1:
The patent implements continuous ion focusing through external RF electrodes that maintain ion confinement along the entire ion path through the differential pumping stages. This continuous focusing action prevents ion loss at orifices by keeping ions confined to the central region, ensuring uninterrupted ion transmission through multiple pressure stages without significant loss
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
The solution enables efficient ion transfer with reduced losses and contamination, ensuring high sensitivity and detection limits in mass analysis by controlling ion energies and residence times, while avoiding electrode contamination and discharges.
Implementation Method 1
at least one first electrode for generating a field for transporting ions along said elongate chamber
Implementation Method 2
A second electric field is applied for confining the ions close to the axis. This is often done with an RF field with low amplitudes on the chamber axis and larger amplitudes away from the axis. Such an RF field creates an effective potential confining the ions to the axis.
Implementation Method 3
The fields are generated by elongated rods that are arranged within the vacuum chambers. It uses radio frequency (RF) fields, which can focus the ions along an axis and additionally can cool the ions through collisions to further increase transmission efficiencies into the mass spectrometer.
Data Source
AI summary
An ion guide chamber comprising a gas-tight elongate chamber, at least one first electrode for generating a field for transporting ions along the elongate chamber and at least one second electrode for generating a field for focusing ions within the elongate chamber. The elongate chamber, e. g. constituted by a glass tube, comprises a resistive structure extending substantially along a main axis of the chamber, whereas the first electrode is constituted by the resistive structure. Furthermore, the second electrode is arranged outside the elongate chamber. Having the RF electrodes arranged outside the vacuum chamber, provides a mechanically simple solution as well as insuring that contamination of the RF electrodes to the analyte gas cannot occur. This allows for a cost-saving design of the RF electrodes and with the corresponding voltages outside the chamber, preferably at atmospheric pressure or high vacuum, avoids discharges within the tube.