Segmented Ion Pump Anode for Cathode Wear Distribution
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Solution Overview
Problem
Ion pumps in mass spectrometers have a limited lifespan due to cathode surface degradation from ion bombardment, particularly in remote sensing applications where maintenance is challenging.
Innovation Solution
The ion pump system incorporates a cylindrical anode tube with deflection plates and a cathode plate design that alters the trajectory of accelerated ions, dispersing their impact across a wider area of the cathode surface, thereby reducing focal point wear and extending the ion pump's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ions are accelerated along the mechanical center axis of the anode tube, then the ion pump achieves effective vacuum pumping, but the cathode surface degrades rapidly due to concentrated ion bombardment at the focal point
Solution Approach 1:
The patent applies asymmetry by offsetting the electrical center axis of the anode tube from its mechanical center axis. This is achieved by applying different voltages to different segments of the anode tube, creating an asymmetric electric field distribution that deflects ions away from the mechanical center axis and distributes their impact across a wider area of the cathode surface, thereby reducing localized degradation
Solution Approach 2:
The patent employs dynamic voltage control of the anode tube segments to continuously vary the electric field configuration. By dynamically adjusting the voltages applied to different segments, the ion trajectory can be modulated over time, preventing permanent focal point formation and distributing wear across the cathode surface throughout the operational cycle
2Productivity
If the ion beam is focused to a narrow trajectory, then pumping efficiency is maximized, but the cathode surface area subjected to intense ion bombardment is minimized leading to rapid wear
Solution Approach 1:
The anode tube is segmented into multiple independent sections that can be controlled separately. This segmentation allows the electric field to be divided and redirected to different spatial regions, distributing the ion beam impact across multiple areas of the cathode surface while maintaining overall pumping efficiency through coordinated segment control
Solution Approach 2:
The patent transitions the ion impact from a one-dimensional focal point along the axis to a two-dimensional distributed pattern across the cathode surface. By using asymmetric voltage control of anode segments, ions are deflected to strike different radial positions on the cathode, effectively adding a spatial distribution dimension to the impact pattern and reducing localized wear
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 design triples the life of the cathode surface and the ion pump system by distributing the ion impact, preventing premature failure and maintaining vacuum integrity.
Implementation Method 1
The plurality of deflection plates may be configured to steer a trajectory of an accelerated ion off the mechanical center axis of the anode tube
Implementation Method 2
The ion pump achieves vacuum by ionizing molecules that drift into a cylindrical anode, and then driving them into a cathode surface with an electric field
Implementation Method 3
The ion pump achieves vacuum by ionizing molecules that drift into a cylindrical anode, and then driving them into a cathode surface with an electric field
Implementation Method 4
The position of the axial center axis is configured to change a local electric field and the trajectory of accelerated ions over time
Data Source
AI summary
Within an ion pump, accelerated ions leave the center portion of an anode tube due to the anode tube symmetry and the generally symmetrical electric fields present. The apparent symmetry within the anode tube may be altered by making the anode tube longitudinally segmented and applying independent voltages to each segment. The voltages on two adjacent segments may be time varying at different rates to achieve a rasterizing process.