Triode Electron Gun Hollow Cathode Back-Streaming Protection
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Solution Overview
Problem
Triode electron guns used in linear particle accelerators face issues with back-streaming electrons impacting the cathode and control grid, causing damage and dark currents due to temperature increases.
Innovation Solution
A hollow cathode electron gun design with a control grid and a coaxial cylinder is employed, which maintains the shape and trajectory of the electron beam, preventing back-streaming electrons from damaging the cathode and control grid by using a hollow cathode and control grid with a center hole, and a cylinder positioned at the center of the cathode to repel unwanted electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control grid is used to control electron beam current, then the ability to change electron beam current quickly and in a controlled fashion is improved, but back-streaming electrons impact the control grid and cathode, raising their temperature and potentially damaging them
Solution Approach 1:
The patent extracts the harmful back-streaming electrons from the system by introducing a repeller electrode that actively removes them before they can impact the cathode and control grid. This separates the useful function (electron beam generation and control) from the harmful effect (electron bombardment damage), allowing the control grid to perform its current modulation function without being damaged by back-streaming electrons.
Solution Approach 2:
The repeller electrode serves as an intermediary component between the control grid and the vacuum environment. It mediates the interaction by creating a potential barrier that prevents back-streaming electrons from reaching the sensitive cathode and control grid surfaces, thus protecting them while allowing the control grid to maintain its function.
2Reliability
If a hollow cathode with center hole and coaxial cylinder is used, then back-streaming electrons are repelled and cathode damage is prevented, but the device complexity increases
Solution Approach 1:
The patent employs a nested structure where the coaxial cylinder is positioned inside the hollow cathode, which itself has a center hole. This nested arrangement allows multiple protective and functional elements to be compactly integrated, reducing the overall space required while maintaining the protective function against back-streaming electrons.
Solution Approach 2:
The introduction of the coaxial cylinder adds a dimensional element to the cathode structure, creating a three-dimensional protective configuration. This dimensional enhancement provides additional protection against back-streaming electrons from multiple angles while maintaining a compact overall structure.
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 effectively reduces the impact of back-streaming electrons, preventing damage and maintaining a stable electron beam trajectory, enhancing the operational efficiency and longevity of the electron gun.
Implementation Method 1
a hollow cathode configured to emit a beam of electrons
Implementation Method 2
An anode is configured to attach and focus the beam of electrons
Implementation Method 3
A control grid is configured to control the beam of electrons emitted from the hollow cathode
Implementation Method 4
A cylinder is positioned substantially coaxial with the hollow cathode and is configured to maintain a shape and trajectory of the emitted beam of electrons
Data Source
AI summary
Vacuum electron devices and linear accelerators include a hollow cathode configured to emit a beam of electrons. An anode is configured to attach and focus the beam of electrons. A control grid is configured to control the beam of electrons emitted from the hollow cathode. A cylinder is positioned substantially coaxial with the hollow cathode and is configured to maintain a shape and trajectory of the emitted beam of electrons.