Ion Beam Modulation for Stable Charge Accumulation
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Solution Overview
Problem
Existing ion accumulation devices face challenges in managing space charge, leading to shifts in ion frequencies and resonance issues due to varying charge flux, which affects the accuracy of mass spectrometry and other ion processing techniques.
Innovation Solution
The method involves controlling the ionic charge flux by determining a fixed accumulation time and modulating the ion beam using techniques like pulse frequency modulation or proportional modulation to maintain a constant space charge density, ensuring optimal ion accumulation and resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion accumulation time is increased to accumulate more charges, then charge quantity increases, but space charge density increases causing ion frequency shifts and resonance issues
Solution Approach 1:
The patent applies periodic action by using pulsed ion beam delivery instead of continuous accumulation. The ion beam is delivered in controlled pulses with specific duty cycles, allowing the accumulation of charges over time while providing rest periods that prevent excessive space charge density buildup. This periodic delivery method resolves the contradiction by enabling sufficient charge quantity accumulation without maintaining continuously high space charge levels that cause frequency shifts.
Solution Approach 2:
The patent implements dynamics by making the ion beam modulation parameters adjustable and time-dependent. The system dynamically adjusts the duty cycle and pulse characteristics of the ion beam based on real-time space charge density monitoring. This dynamic control allows the system to optimize charge accumulation while preventing harmful space charge effects, resolving the contradiction between accumulating sufficient charges and avoiding excessive space charge density.
2Productivity
If ion beam flux is increased to improve productivity, then charge accumulation speed increases, but space charge density increases causing frequency shifts
Solution Approach 1:
The patent uses periodic pulsed ion beam delivery where the beam is turned on and off in controlled cycles. During the 'on' portion of the cycle, ion flux is high for rapid accumulation; during the 'off' portion, flux is reduced allowing space charge density to decrease. This periodic modulation maintains high average productivity while preventing continuous high flux from causing frequency shifts, thus resolving the contradiction between accumulation speed and frequency stability.
Solution Approach 2:
The patent implements feedback control by monitoring ion frequency or space charge density and adjusting the ion beam flux accordingly. When frequency shifts indicate excessive space charge density, the system automatically reduces the ion beam flux or duty cycle. This feedback mechanism ensures that productivity is maximized only when frequency stability is maintained, resolving the contradiction between accumulation speed and measurement precision.
3Loss of time
If fixed accumulation time is used to ensure consistent scan-to-scan times, then timing precision improves, but charge quantity varies with flux changes
Solution Approach 1:
The patent applies dynamics by making the ion beam flux variable while maintaining fixed accumulation time. The system dynamically adjusts the ion beam duty cycle or intensity during the fixed accumulation period to compensate for flux variations. This ensures that the accumulation time remains constant for consistent scan-to-scan timing, while the dynamic flux adjustment maintains relatively stable charge quantity despite source variations.
Solution Approach 2:
The patent changes the ion beam parameters (flux, duty cycle, pulse width) during the fixed accumulation time to compensate for source variations. By adjusting these parameters dynamically, the system maintains consistent accumulation duration for timing precision while compensating for flux changes to maintain stable charge quantity, resolving the contradiction between time consistency and charge quantity stability.
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 maintains a stable ion accumulation process, reducing unwanted space charge effects and ensuring consistent scan-to-scan times, even with varying ion flux, thereby enhancing the precision and reliability of ion processing and mass analysis.
Implementation Method 1
an ion beam modulator that deflects an ion beam by a desired degree off an ion beam axis
Implementation Method 2
An alternating voltage may be applied to the center electrode 106 to form a three-dimensional quadrupolar restoring force directed towards the center of the electrode assembly. Ions are confined within an electrodynamic quadrupole field when their trajectories are bounded in the (r) and (z) directions.
Implementation Method 3
Ions with a mass-to-charge ratio having a natural (or secular) frequency of oscillation matching the frequency of the supplemental voltage will be ejected from the trap in the direction of the applied supplemental field.
Data Source
AI summary
A method for controlling charge flux into a charge accumulation device includes determining a charge accumulation time during which charges are to be accumulated in the charge accumulation device, measuring a charge flux of a first ion beam produced from an ion source, determining a target number of charges to be accumulated in the charge accumulation device during the charge accumulation time based on the measured charge flux and, based on the determined target number of charges, modulating a second ion beam produced from the ion source to cause the target number of charges from the second ion beam to be accumulated in the charge accumulation device during the charge accumulation time. An ion processing device is configured for controlling the charge flux. An ion beam modulator modulates the ion beam.