MCP Detector Acceleration Electrode for Time Response
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Solution Overview
Problem
Existing time-of-flight mass spectrometry (TOF-MS) systems face limitations in mass resolution due to constraints on the channel diameter of microchannel plate (MCP) detectors, which affect the time response characteristic of detected peaks, making it difficult to extend the time of flight or reduce the full width at half maximum (FWHM) of detected peaks.
Innovation Solution
An MCP unit with a specific structure that includes an MCP assembly, an anode, and an acceleration electrode, where the acceleration electrode is positioned between the MCP and the anode to control the rise and fall times of detected peaks, allowing for arbitrary adjustment of the distances between these components to improve the time response characteristic without relying on the channel diameter of the MCP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the channel diameter of MCP is reduced to improve time response characteristic, then the rise time and fall time of detected peaks are shortened, but the manufacturing precision and reliability of MCP deteriorate due to difficulty in maintaining structural integrity
Solution Approach 1:
An acceleration electrode is introduced as an intermediary component between the MCP and anode. This electrode mediates the electron acceleration process, allowing the MCP channel diameter to be optimized for manufacturing reliability while the acceleration electrode controls the time response characteristic through adjustable voltage and positioning.
Solution Approach 2:
The invention changes the control parameter for time response from MCP channel diameter to acceleration electrode voltage and position. By adjusting the acceleration voltage and distance between the acceleration electrode and anode, the rise time and fall time can be controlled without modifying the MCP structure, thus avoiding manufacturing precision issues.
2Measurement precision
If the distance between MCP and anode is reduced to improve detection sensitivity, then the signal strength increases, but the waveform distortion and ringing increase due to capacitive effects
Solution Approach 1:
The acceleration electrode serves as a mediator that separates the MCP-anode capacitive coupling from the electron acceleration function. By positioning the acceleration electrode between the MCP and anode with appropriate spacing and voltage, it reduces the direct capacitive effect while maintaining electron acceleration, thereby reducing waveform distortion and ringing.
3Productivity
If the MCP channel diameter is increased to improve detection efficiency, then more electrons are detected, but the time response characteristic deteriorates with longer rise time and fall time
Solution Approach 1:
The acceleration electrode acts as a mediator that decouples the relationship between MCP channel diameter and time response. This allows the MCP to be designed with larger channel diameter for higher detection efficiency, while the acceleration electrode parameters (voltage, position) are adjusted to achieve the desired time response characteristic.
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 FWHM of detected peaks, thereby enhancing the mass resolution and time response characteristic of the TOF-MS system, allowing for improved waveform shaping and detection sensitivity.
Implementation Method 1
an acceleration electrode, arranged between the MCP and the anode
Implementation Method 2
a great number of electrons (secondary electrons multiplied by the respective MCPs) are released from the MCP cluster 2 in response thereto
Data Source
AI summary
The present invention relates to an MCP unit or the like having a structure intended to achieve a desired time response characteristic, without depending on a limitation imposed by a channel diameter of MCP. The MCP unit comprises the MCP for releasing secondary electrons internally multiplied in response to incidence of charged particles, an anode arranged in a position where the secondary electrons reach, and an acceleration electrode arranged between the MCP and the anode. In particular, the acceleration electrode includes a plurality of openings which permit passing of the secondary electrons migrating from the MCP toward the anode. Further, the acceleration electrode is arranged such that the shortest distance B between the acceleration electrode and the anode is longer than the shortest distance A between the MCP and the acceleration electrode. Thus, an FWHM of a detected peak appearing in response to the incidence of the charged particles is remarkably shortened.