Mass Spectrometer RF Power Supply Response Time
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Solution Overview
Problem
Existing quadrupole power supplies in mass spectrometers have slow response times for ramping up and down, which affects the speed and accuracy of ion ejection and filtering, limiting the speed at which ions reach analysis components and impacting analytical results.
Innovation Solution
The apparatus comprises a first and second resonant LC circuit connected in cascade with a step-up transformer providing voltage gain, reducing the loaded Q of the resonant LC circuits and enhancing the response time by incorporating a DC power source and an RF power source operating within specific frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple resonant LC circuit is used to provide power to the quadrupole, then the device complexity is reduced, but the response time increases to 40-50 µs
Solution Approach 1:
The patent divides the power supply system into multiple resonant LC circuits (first, second, and optional third circuits) with different Q factors. Each circuit serves a specific function: the first circuit provides initial power with moderate Q, the second circuit with higher Q extends the frequency response, and the optional third circuit optimizes performance at specific frequencies. This segmentation allows the system to achieve fast response time without requiring a single overly complex circuit design.
Solution Approach 2:
The patent introduces the dimension of frequency distribution by operating multiple LC circuits at different resonant frequencies. The first circuit operates at a lower frequency with moderate Q factor, while the second circuit operates at a higher frequency with higher Q factor. This frequency distribution enables the system to achieve fast response across a broader operational range without increasing individual circuit complexity.
2Reliability
If the loaded Q of the resonant LC circuit is increased to improve frequency response, then the selectivity is improved, but the response time increases
Solution Approach 1:
The patent segments the frequency response requirement across multiple LC circuits with different Q factors. The first resonant LC circuit operates with a lower Q factor (e.g., Q1 ≈ 50-100) providing fast response, while the second resonant LC circuit operates with a higher Q factor (e.g., Q2 ≈ 100-200) providing superior frequency selectivity. This segmentation allows each circuit to be optimized for its specific Q range, achieving both fast response and high selectivity without the trade-off present in a single-circuit design.
Solution Approach 2:
The patent changes the Q factor parameter across different circuit stages. By designing the first LC circuit with moderate Q and the second LC circuit with higher Q, the system achieves a composite frequency response that maintains fast response time while improving selectivity. The parameter change in Q factor across circuits allows optimization of both response speed and frequency discrimination.
3Productivity
If the ramp speed of RF power is increased to improve ion ejection speed, then the productivity is improved, but the control precision deteriorates at kV operating voltages
Solution Approach 1:
The patent applies preliminary action by using the first resonant LC circuit with moderate Q factor to rapidly establish the initial RF power level and voltage conditions. This preliminary circuit prepares the system state quickly, after which the second high-Q circuit takes over to maintain precise voltage control during steady-state operation. This preliminary action enables fast ramping without sacrificing control precision during the critical ion ejection phase.
Solution Approach 2:
The patent implements dynamic operation by switching between different circuit configurations and Q factor settings during the power ramping process. During the ramp-up phase, the system utilizes the first circuit's faster response characteristics, while during steady-state ion ejection, the system engages the second circuit's superior voltage control. This dynamic approach allows the system to optimize for speed during transitions and for precision during critical operations.
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 configuration significantly reduces the response time from 40-50 µs to approximately 5 µs for both ramping up and down, improving the speed and accuracy of ion ejection and filtering in mass spectrometers.
Implementation Method 1
a first resonant LC circuit... at least one inductor for forming a second resonant LC circuit with the quadrupole
Implementation Method 2
an inductor L1, the quadrupole providing the capacitance C1 for the resonant LC circuit
Implementation Method 3
a step-up transformer connected in parallel to the RF power source on a primary side and the first resonant LC circuit on a secondary side, the step-up transformer providing voltage gain for the RF signal
Data Source
Figure 1
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AI summary
An apparatus for providing power to a multipole in a mass spectrometer is provided. The apparatus comprises a first resonant LC circuit; at least one inductor for forming a second resonant LC circuit with the multipole, the second resonant LC circuit connected in cascade with the first resonant LC circuit, when the at least one inductor is connected to the multipole; an RF power source for providing an RF signal; and a step-up transformer connected in parallel to the RF power source on a primary side and the first resonant LC circuit on a secondary side, the step-up transformer providing voltage gain for the RF signal thereby reducing the loaded Q of the resonant LC circuits.