Ion Trap Gas Beam Cooling and Separation
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Solution Overview
Problem
Existing ion trap technologies face limitations in cooling ions to low emittance due to gas-related issues, such as fragmentation and high operational complexity, especially when integrating with mass spectrometers, as they require high vacuum conditions and struggle with gas carry-over and pressure management.
Innovation Solution
A method involving a directed beam of gas through the ion trap's trapping region to change the kinetic energy of ions, allowing for efficient cooling and storage at reduced pressure, minimizing ion fragmentation and gas load, while enabling flexible operation with various mass analyzers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a gas is introduced into the ion trap for cooling ions, then the ions can be cooled to lower temperatures, but the gas causes fragmentation of ions and increases gas load on the mass spectrometer
Solution Approach 1:
The gas flow is segmented into discrete pulsed injections rather than continuous flow. Gas is introduced in controlled pulses during ion storage, allowing cooling to occur in intervals while minimizing fragmentation during ion ejection and reducing gas load on the mass spectrometer.
Solution Approach 2:
Ions are pre-cooled in the ion trap using gas pulses before being ejected to the mass spectrometer. This preliminary cooling action occurs in a controlled environment where gas pressure can be managed, preventing fragmentation during the critical ejection and analysis phases.
2Temperature
If gas is continuously present in the ion trap for cooling, then ions can be effectively cooled, but the operational speed is significantly limited and gas carry-over occurs
Solution Approach 1:
Gas is introduced periodically in pulses rather than continuously. During pulse intervals, ions are cooled; during non-pulse intervals, the trap is evacuated to reduce gas pressure, enabling faster ion ejection and preventing gas carry-over to the mass spectrometer.
Solution Approach 2:
The system maintains continuous operational capability by alternating between gas injection phases (for cooling) and evacuation phases (for rapid ion ejection). This continuous cycling ensures both effective cooling and high operational speed without compromising either function.
3Temperature
If the ion trap operates at high pressure with gas for cooling, then ion cooling is effective, but the path length must be minimized to prevent external mass separation
Solution Approach 1:
The trapping and ejection paths are segmented into distinct spatial and temporal zones. Gas is confined to the trapping region during cooling phases, while ejection occurs through evacuated regions, eliminating the need to minimize the overall path length and allowing more flexible trap design.
Solution Approach 2:
A differential pumping system acts as an intermediary between the high-pressure trapping region and the low-pressure ejection region. This mediator allows ions to transition from a gas-filled cooling environment to a vacuum ejection environment without requiring the entire path to be minimized.
4Loss of substance
If small apertures are used to prevent gas carry-over, then gas load is reduced, but cost and complexity increase and performance decreases
Solution Approach 1:
The trap undergoes periodic cycles of gas injection and evacuation. During evacuation phases, gas pressure is reduced before ion ejection, preventing gas carry-over without requiring small apertures. This temporal control eliminates the need for restrictive spatial constraints.
Solution Approach 2:
The mechanical constraint of small apertures is replaced by temporal control through pulsed gas injection and active evacuation. Instead of physically restricting gas flow through small openings, the system uses timed gas introduction and removal to prevent carry-over, reducing complexity and improving performance.
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 effectively cools ions to low temperatures without significant dissociation, reduces gas load on the mass spectrometer system, and allows for optimized ion injection into mass analyzers, enhancing resolving power and sensitivity by maintaining low pressure within the ion trap.
Implementation Method 1
directing a beam of gas through the trapping region, so as to change the kinetic energy of the trapped ions thereby
Implementation Method 2
a light gas, such as hydrogen or helium, which is adiabatically cooled during formation and directed as a jet
Data Source
AI summary
A method of changing the kinetic energy of ions is provided, comprising: trapping ions in a trapping region of an ion trap; and directing a beam of gas through the trapping region, so as to change the kinetic energy of the trapped ions thereby. Also provided is a method of separating ions, the method comprising: causing ions to enter a trapping region of an ion trap along a first axis of the trapping region; directing a beam of gas along the first axis and applying an electric potential in the direction of the first axis so as to cause separation of the ions based on their ion mobility. An ion trap and a mass spectrometer for performing the methods are also provided.