Electron Multiplier Bias Voltage Segmentation
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Solution Overview
Problem
Existing electron multipliers face challenges in achieving high linear output currents due to voltage perturbations and noise interference, particularly at high output signal levels, with methods like zener diodes and low resistance voltage dividers leading to performance limitations and increased noise.
Innovation Solution
The use of multiple power supplies to apply bias voltages differentially across electron emissive surfaces, where the terminal surfaces draw a higher electrical current than the remainder surfaces, reducing voltage perturbations and power dissipation, and allowing for more linear signal amplification over a greater operational range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zener diodes are used to stabilise dynode voltages at higher output currents, then voltage stability is improved, but electrical noise increases and temperature dependence deteriorates performance
Solution Approach 1:
The patent removes zener diodes from the voltage divider chain between dynodes, extracting the noise and temperature dependence problems they introduce. Instead, separate power supplies are used to provide stable voltages to each dynode without the harmful characteristics of zener diodes.
Solution Approach 2:
The voltage divider chain is segmented into multiple independent power supply units, each powering a specific dynode. This segmentation eliminates the need for zener diodes in the chain, thereby removing the source of electrical noise and temperature-dependent voltage instability.
2Reliability
If low resistance voltage divider chain is used to increase bleed current, then voltage perturbation is reduced, but power dissipation increases and heat generation causes elevated background noise
Solution Approach 1:
The voltage divider chain is divided into multiple segments, each powered by its own power supply. This allows each segment to operate with optimal resistance values without requiring the entire chain to have low resistance, thereby reducing overall power dissipation while maintaining voltage stability at each dynode.
Solution Approach 2:
The patent changes the operating parameters of the voltage divider by using multiple power supplies with different voltage levels and currents for different dynodes. This allows optimization of power dissipation and heat generation for each segment independently, avoiding the need for high bleed current through the entire chain.
3Reliability
If low resistance voltage divider is used, then high output current linearity is improved, but expensive and high power high voltage power supply is required
Solution Approach 1:
The single high voltage power supply is segmented into multiple lower-power power supplies, each responsible for a portion of the dynodes. This segmentation allows the system to achieve high output current linearity without requiring one expensive, high-power power supply, instead using multiple simpler, lower-power units.
Solution Approach 2:
The patent changes the voltage and current parameters distributed to each dynode by using multiple power supplies with optimized parameters for their respective positions in the chain. This allows high linearity at high output currents to be achieved without requiring excessive power from a single supply, reducing overall system complexity and cost.
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 approach enhances the linearity and reduces power requirements, minimizing voltage perturbations and noise, while maintaining low power dissipation and avoiding the need for high-specification high voltage power supplies.
Implementation Method 1
Electron multipliers generally operate by way of secondary electron emission whereby the impact of a single or multiple particles on the multiplier impact surface causes single or (preferably) multiple electrons associated with atoms of the impact surface to be released
Implementation Method 2
one or more power supplies configured to apply bias voltage(s) to one or more of the emissive surfaces, the bias voltage(s) being sufficient to form the amplified electron signal
Data Source
AI summary
An apparatus for amplifying an electron signal caused by the impact of a particle with an electron emissive surface. The apparatus includes: a first electron emissive surface configured to receive an input particle and thereby emit one or more secondary electrons, a series of second and subsequent electron emissive surfaces configured to form an amplified electron signal from the one or more secondary electrons emitted by the first electron emissive surface, and one or more power supplies configured to apply bias voltage(s) to one or more of the emissive surfaces. The bias voltage(s) is sufficient to form the amplified electron signal. The apparatus is configured such that the terminal electron emissive surface(s) of the series of second and subsequent electron emissive surfaces draw a higher electrical current than that of the remainder electron emissive surface(s). The apparatus may be used as part of detector in a mass spectrometer, for example.