Incident Dynode Angle and Material Segmentation for Mass Spectrometry
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Solution Overview
Problem
High energy dynodes in mass spectrometers generate noise and spurious signals, particularly in the presence of helium, and have limited sensitivity for both positive and negative ion detection modes.
Innovation Solution
The dynode is arranged to receive incoming ions at an angle greater than 30° from the surface normal, with an offset geometry and electrostatic fields to deflect neutral particles, and different surface materials are used for positive and negative ion detection modes, allowing selective steering of ion beams for optimal secondary particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high energy dynode is used to increase ion detection sensitivity, then secondary particle yield increases, but noise and spurious signals are generated
Solution Approach 1:
The dynode surface is divided into multiple discrete impact zones or segments, each optimized for specific ion types or energy ranges. This segmentation allows selective enhancement of signal generation for target ions while reducing noise generation from other particle types, particularly helium ions.
Solution Approach 2:
Different regions of the dynode surface are given different local properties through varied surface materials, coatings, or geometries. This enables certain areas to be highly sensitive to specific ions while being less responsive to noise-generating particles, creating spatially differentiated detection zones.
2Measurement precision
If high energy dynode is used for positive ion detection, then sensitivity improves, but negative ion detection capability is limited
Solution Approach 1:
The dynode is designed with multi-functional capabilities by incorporating multiple surface materials or configurable regions that can be selectively activated. This allows the same dynode structure to optimize detection for both positive and negative ions, as well as different ion masses and energies, without requiring separate detection systems.
Solution Approach 2:
The dynode system incorporates dynamic control mechanisms such as variable voltage application to different surface regions or switchable surface configurations. This enables real-time adaptation of the dynode's detection characteristics to match the specific ion type being detected, whether positive or negative ions.
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 enhances sensitivity and minimizes noise by increasing secondary particle yield and allowing for practical differentiation in surface materials for different detection modes, effectively addressing the limitations of current high energy dynode designs.
Implementation Method 1
an incident dynode, adapted to be charged to a pre-determined electrical potential, having a surface positioned in said chamber to be impacted by said primary charged particles at an angle of incidence greater than 30° from the surface normal and in response to said impact to generate a stream of secondary charged particles
Implementation Method 2
an electrode configuration is provided to generate an electrostatic field for deflecting said primary charged particles to said dynode surface while neutral particles remain on said trajectory
Implementation Method 3
An HED, is an ion impact plate that is maintained at a high electrical potential (typically between 5 kV and 15 kV). Because of the high potential maintained on the HED, ions acquire considerable energy when approaching its surface
Data Source
AI summary
Apparatus for amplifying a stream of primary charged particles comprises a body defining a chamber and an entrance aperture for receiving the stream of primary charged particles into the chamber, and an incident dynode, adapted to be charged to a pre-determined electrical potential, having a surface positioned in the chamber to be impacted by said primary charged particles at an angle of incidence greater than 30° from the surface normal and in response to the impact to generate a stream of secondary charged particles.