Electrostatic Lens Insulating Structure for High Voltage Reliability
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Solution Overview
Problem
Electrostatic lenses in charged particle beam columns face challenges with electrical breakdown due to flashovers, particularly at triple points where voids occur, leading to a reduction in dielectric strength and lens performance, especially when high electric fields are applied between closely positioned conductive plates.
Innovation Solution
The design incorporates an insulating structure with an overhanging portion and an indented portion to create a gap between the insulating material and the conductive plates, reducing electric field enhancement at voids, especially at the negative electrode, and includes a conductive coating on the insulating structure to equalize the surface potential, thereby preventing field enhancement in voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between conductive plates is reduced to maintain compact lens structure, then the lens size is reduced, but the electric field strength increases leading to higher risk of electrical breakdown and flashover
Solution Approach 1:
A conductive coating layer is applied to the insulating structure surface to act as an intermediary that equalizes surface potential and prevents field enhancement at void locations. This coating serves as a mediator between the insulating structure and the electric field, eliminating the harmful field concentration effect while allowing the compact lens structure to maintain high reliability.
2Device complexity
If conventional insulating structures are used without surface coating, then the structure is simple, but voids at triple points cause electric field enhancement leading to flashover
Solution Approach 1:
The insulating structure is combined with a conductive coating layer to form a composite structure. This composite material approach allows the system to benefit from both the insulating properties of the base structure and the field-equalizing properties of the conductive coating, effectively preventing flashover while maintaining structural simplicity.
3Power
If high electric fields (10-50 V/μm) are applied between closely positioned plates to achieve desired lens performance, then the lens performance is improved, but the risk of electrical discharge along insulator surfaces increases
Solution Approach 1:
The conductive coating is applied in advance to the insulating structure surface to preemptively counteract the harmful effect of field enhancement. By establishing a uniform potential distribution before the high electric field is applied, the coating prevents the initiation of electrical discharges even when high power fields (10-50 V/μm) are applied between closely positioned plates.
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 allows the electrostatic lens to withstand high electric fields without flashover, maintaining performance and reducing the risk of electrical discharges, enabling operation up to 25-50 V/μm without degradation.
Implementation Method 1
includes a conductive coating on the insulating structure to equalize the surface potential, thereby preventing field enhancement in voids
Implementation Method 2
The design incorporates an insulating structure with an overhanging portion and an indented portion to create a gap between the insulating material and the conductive plates, reducing electric field enhancement at voids
Implementation Method 3
This configuration allows the electrostatic lens to withstand high electric fields without flashover, maintaining performance and reducing the risk of electrical discharges, enabling operation up to 25-50 V/μm without degradation
Data Source
AI summary
An electrostatic lens comprising a first conductive plate with a first aperture, a second conductive plate with a second aperture, the second aperture being substantially aligned with the first aperture, a voltage supply for supplying a first voltage to the first conductive plate and a second voltage to the second conductive plate, the first voltage being lower than the second voltage, and an insulating structure for separating the first conductive plate from the second conductive plate. The insulating structure comprises a first portion in contact with the first conductive plate and a second portion in contact with the second conductive plate, the first portion having an overhanging portion and the second portion having an indented portion at an edge of the insulating structure, so that a gap is formed between the overhanging portion and the second conductive plate.