Ceramic Accelerator Structure With Graded Resistivity Near the Cathode
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Solution Overview
Problem
Existing charged particle beam apparatuses face challenges in reducing electric field concentration near the cathode, leading to insulation resistance deterioration and discharge, which conventional methods like adjusting surface resistivity fail to adequately address.
Innovation Solution
A ceramic body with varying surface resistivity regions, including a low resistance layer near the cathode and a high resistance layer elsewhere, connected by an electric field relaxation layer, to distribute voltage and reduce electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface resistivity of the insulator is adjusted to prevent charge-up, then insulation resistance is improved, but electric field concentration near the cathode cannot be reduced
Solution Approach 1:
The insulator is divided into multiple regions with different surface resistivity values. The first region (near the cathode) has a first surface resistivity value, while the second region (away from the cathode) has a second surface resistivity value. This local differentiation allows each region to perform its specific function: the first region reduces electric field concentration at the critical triple junction, while the second region maintains overall insulation resistance.
Solution Approach 2:
The insulator surface is segmented into distinct regions with different electrical properties. By dividing the insulator into a first region adjacent to the cathode and a second region farther from the cathode, each segment can be optimized independently for its specific operational requirements, resolving the contradiction between local field control and global insulation.
2Object-affected harmful factors
If the shape of the insulator is changed or the inner wall is separated from structures to reduce electric field concentration, then electric field distribution is improved, but the size of the insulator increases
Solution Approach 1:
Instead of changing the physical shape or dimensions of the insulator, the invention changes the electrical parameter (surface resistivity) of different regions. This allows electric field concentration to be reduced by modifying the electrical characteristics rather than the geometric characteristics, thereby avoiding an increase in insulator size.
3Reliability
If a resistance layer is applied to the inner wall surface to permit current flow and prevent charge-up, then thermal electron accumulation is reduced, but electric field concentration at the triple junction causes discharge
Solution Approach 1:
The resistance layer is applied with spatially varying surface resistivity values. The first region near the triple junction has a lower surface resistivity to allow current flow that prevents charge-up and reduces electric field concentration, while the second region has higher surface resistivity to maintain insulation. This local quality differentiation prevents discharge at the critical triple junction while maintaining overall insulation resistance.
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 minimizes electric field concentration, enhancing insulation resistance and preventing discharge, thus maintaining stable operation of the charged particle beam apparatus.
Implementation Method 1
the surface resistivity of the first region is lower than the surface resistivity of the second region
Data Source
AI summary
Provided are a structure for particle acceleration and a charged particle beam apparatus, which enable the suppression of electric field concentration occurring near a negative electrode part. The structure for particle acceleration includes: a ceramic body 1 having a through hole 10 formed by an inner wall surface; and a negative electrode 2 and a positive electrode 3 which are arranged, respectively, on one end and the other end of the through hole 10 in the ceramic body. The inner wall surface of the ceramic body 1 is configured such that a first region 22, which is electrically connected with the negative electrode 2, and a second region 23, which is electrically connected with the positive electrode 3, are electrically connected to each other. The surface resistivity of the first region 22 is lower than the surface resistivity of the second region 23.