Charged Particle Gun Shielding for Discharge and Voltage Accuracy
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Solution Overview
Problem
Existing charged particle beam devices face challenges in protecting the charged particle source from electrical discharging, which leads to reduced device performance due to parasitic inductance, load current, and AC accuracy deterioration.
Innovation Solution
A charged particle gun configuration where the extraction voltage and acceleration voltage are superposed and supplied to the charged particle beam source, with the wiring covered by first and second enclosures acting as Faraday cages, effectively reducing stray capacitance and electrical discharging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the charged particle source is covered by a conductor enclosure to reduce stray capacitance, then the transient electric field during electrical discharging is restrained, but parasitic inductance of wiring still causes overvoltage between the charged particle source and extraction electrode
Solution Approach 1:
The patent employs a nested enclosure structure where a first enclosure connected to the extraction electrode contains a second enclosure connected to ground. This nested configuration creates multiple shielding layers that progressively reduce parasitic inductance and stray capacitance, thereby improving the protection effect against electrical discharging while maintaining low transient electric fields.
Solution Approach 2:
The patent introduces an intermediate enclosure structure between the charged particle source and the external environment. This intermediate structure acts as a mediator that decouples the direct path for parasitic inductance, providing a controlled impedance path that reduces overvoltage while maintaining the shielding effect against transient electric fields.
2Power
If high DC high voltage is applied to the charged particle source to achieve several tens of kV to several hundreds of kV beam energy, then device performance such as image resolution and focal depth is improved, but electrical discharging generates stronger transient electric field that damages the charged particle source
Solution Approach 1:
The nested enclosure structure provides progressive shielding at multiple voltage levels, allowing high DC high voltage to be applied to the charged particle source while the enclosures create intermediate shielding zones that reduce the transient electric field strength during electrical discharging events.
Solution Approach 2:
The conductor enclosures are pre-configured with specific connectivity (first enclosure to extraction electrode, second enclosure to ground) to create a protective cushioning effect before electrical discharging occurs. This pre-established shielding network reduces the impact of transient electric fields on the charged particle source during high voltage operation.
3Device complexity
If the extraction voltage source and acceleration voltage source are combined to supply superposed voltage to the charged particle beam source, then circuit complexity is reduced, but load current causes deterioration of DC and AC accuracy
Solution Approach 1:
The patent segments the voltage supply system into separate extraction voltage source and acceleration voltage source channels, each with independent enclosures. This segmentation prevents load current from one source from affecting the accuracy of the other source, while the enclosures provide electromagnetic shielding to maintain signal integrity.
Solution Approach 2:
The patent applies different enclosure connectivity configurations to different parts of the circuit: the first enclosure is connected to the extraction electrode while the second enclosure is connected to ground. This local differentiation allows each voltage source to maintain its accuracy independently while reducing overall circuit complexity through shared shielding infrastructure.
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 provides robust protection for the charged particle source against electrical discharging, maintains high DC and AC accuracy, and enhances the overall performance of the charged particle beam device.
Implementation Method 1
the wiring covered by first and second enclosures acting as Faraday cages, effectively reducing stray capacitance and electrical discharging effects
Implementation Method 2
a stray capacitance of the charged particle source to the ground is reduced and a transient electric field during electrical discharging is restrained
Data Source
AI summary
The present disclosure provides a charged particle beam device capable of simultaneously achieving protection of a charged particle source against electrical discharging inside a charged particle gun and highly accurate control of the charged particle gun, for both DC and AC components. A charged particle gun according to the present disclosure is configured such that an extraction voltage and an acceleration voltage are superposed and supplied to a charged particle beam source, a wiring between the charged particle beam source and a voltage circuit is covered with first and second enclosures, the first enclosure is configured to be connected to an extraction electrode, and the second enclosure is configured to be connected to an acceleration electrode and to a reference voltage of the voltage circuit.