Cascaded Phosphor Ion Imaging Detector for Mass Spectrometers
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Solution Overview
Problem
Conventional mass spectrometer detectors face a trade-off between instrument resolution and sensitivity, with high resolution requiring narrow pass bands that result in few ions passing through, while high sensitivity degrades mass-to-charge ratio resolution.
Innovation Solution
A detector system employing a cascaded phosphor imaging system and alternative ion-to-electron conversion technologies, such as metal channel dynodes or silicon photomultiplier arrays, to enhance dynamic range and sensitivity without the need for high-gain microchannel plates, allowing for improved ion imaging and reduced system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-gain microchannel plates are used to enhance sensitivity, then sensitivity and dynamic range are improved, but device complexity and long-term costs increase
Solution Approach 1:
The patent segments the ion detection function into two distinct stages: (1) ion-to-electron conversion using low-gain converters (metal channel dynodes or silicon photomultiplier arrays), and (2) photonic signal amplification using cascaded phosphor imaging systems. This segmentation allows each component to be optimized independently, replacing the need for a single high-gain microchannel plate with a coordinated system of lower-gain components that achieves equivalent or superior sensitivity while reducing complexity and cost.
Solution Approach 2:
The patent substitutes the mechanical/electronic amplification mechanism of high-gain microchannel plates with an optical amplification mechanism using phosphor imaging systems. The cascaded phosphor stages convert electrons to photons and back to electrons, providing signal amplification through optical processes rather than direct electronic multiplication, thereby achieving high sensitivity without the complexity of high-gain electron multipliers.
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 provides enhanced sensitivity and dynamic range, reducing long-term system costs and maintaining high mass resolving power, especially for weak ion fluxes, by using lower gain ion-to-electron converters and high-gain photonic signal amplification.
Implementation Method 1
a first microchannel plate positioned to receive the ions and output electrons
Implementation Method 2
a phosphor coating disposed on a substrate plate of the first gain stage. In operation, electrons generated at the first dynode are accelerated in the direction of the phosphor coating by application of an electrical potential difference
Implementation Method 3
a photocathode disposed on a substrate plate of the second gain stage. Some of the photons emitted by the phosphor propagate through the substrate plate of the first gain stage and impinge upon the photocathode, thereby generating a second set of electrons
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A detector system for a mass spectrometer comprises: a metal channel dynode (MCD) comprising at least one perforated metal plate configured to receive the exiting ions and eject electrons in response; a plurality of electron-to-photon converters arranged in a parallel stacked configuration, each such converter comprising a substrate plate having a phosphor coating on a first face; and an electrode film disposed on the phosphor coating; at least one photocathode, each of the at least one photocathode disposed between a respective pair of the plurality of electron-to-photon converters; an optical detector optically coupled a last one of the electron-to-photon converters; and at least one direct current power supply configured to apply, in operation, a respective bias electrical potential to the MCD and each of the electrode films and photocathodes.