Conjoined Ion Trap Layout for Cross-Pressure Ion Transfer
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Solution Overview
Problem
Existing extraction traps face challenges in efficiently capturing and rapidly thermalizing ions from several eV energy while maintaining low pressures required by time-of-flight and orbital trapping mass analyzers, leading to ion transfer inefficiencies and limited analyser repetition rates.
Innovation Solution
A conjoined ion trap design with independent RF power supplies for high and low-pressure regions, using a gas conductance restriction with minimal barrier to allow low-energy ion transfer between regions, enabling parallelized accumulation and extraction of ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-pressure ion trap is used to both accumulate and extract ions, then the device structure is simple, but ion transfer efficiency is low and analyser repetition rate is limited
Solution Approach 1:
The ion trap is divided into two separate pressure regions: a high-pressure accumulation region and a low-pressure extraction region. Each region operates independently with its own RF power supply, allowing simultaneous ion accumulation at high pressure while maintaining low pressure conditions for efficient extraction to the mass analyser, thereby increasing repetition rate without excessive structural complexity
Solution Approach 2:
The system adds the pressure dimension as a differentiating factor between accumulation and extraction functions. By operating at different pressure levels simultaneously in different spatial zones, the system can perform both functions concurrently rather than sequentially, improving productivity
2Temperature
If high gas pressure is used for ion accumulation and cooling, then ion thermalization is efficient, but mass analyser performance deteriorates due to excessive gas pressure
Solution Approach 1:
The system segments the ion processing function into two pressure zones: high-pressure region for efficient ion cooling and thermalization, and low-pressure region for mass analysis. The gas conductance restriction creates a pressure barrier that allows ions to be cooled at high pressure then transferred to the low-pressure analyser region, resolving the conflict between cooling efficiency and analyser performance
Solution Approach 2:
The gas conductance restriction acts as an intermediary element between the high-pressure accumulation region and low-pressure analyser region. It restricts gas flow to maintain the pressure differential while allowing ion passage, enabling efficient ion cooling without compromising mass analyser performance
3Reliability
If gas conductance restriction is increased to maintain pressure differential, then pressure separation is effective, but ion transfer efficiency decreases
Solution Approach 1:
The system optimizes the gas conductance restriction parameters (aperture size, shape, position) to achieve the minimum necessary barrier that maintains pressure differential while allowing efficient ion transfer. By carefully tuning these parameters, the system balances pressure separation effectiveness with ion transfer 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 design achieves high repetition rates and efficient ion processing by minimizing cooling times and ion losses, allowing simultaneous handling of multiple ion packets in different pressure regions.
Implementation Method 1
a gas conductance restriction, configured to restrict gas flow from the relatively high gas pressure region to the relatively low gas pressure region
Implementation Method 2
configured to receive RF voltages from a first RF power supply for generating a first RF field that confines ions in a trapping region
Implementation Method 3
Upon entering the trap, ions are cooled by collisions with buffer gas, usually nitrogen or helium, forming a compressed packet
Data Source
AI summary
A mass spectrometer comprises: a first ion optical device in a relatively low gas pressure region; a second ion optical device in a relatively high gas pressure region, the first and second ion optical devices receiving respective RF voltages from respective RF power supplies for generating respective RF fields that confine ions in respective trapping regions of the ion optical devices; and a gas conductance restriction, restricting gas flow from the relatively high gas pressure region to the relatively low gas pressure region, the gas conductance restriction having an aperture to allow ions to pass from the second to the first ion optical device. The first and second RF power supplies are independent to allow the RF voltages for generating the first RF field to have a different amplitude from the RF voltages for generating the second RF field.