Electron Gun Cathode Shield Gap Design
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Solution Overview
Problem
In electron guns with grids, suppressing side electron emission and reducing heater energy consumption is challenging due to thermal coupling and physical contact issues between the cathode and cathode shield.
Innovation Solution
A cathode shield made of electrically conductive material is positioned near the cathode's side surface but not in direct physical contact, with a gap to minimize electron emission and thermal coupling, maintaining the same electric potential as the cathode to control electron flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cathode shield is disposed in direct physical contact with the cathode to suppress side electron emission, then electron beam focus is improved, but thermal energy loss increases and heater power consumption rises
Solution Approach 1:
The patent introduces an intermediary substance (insulating material or vacuum gap) between the cathode shield and cathode, which electrically isolates them while maintaining their spatial proximity. This allows the cathode shield to suppress side electron emission through electrostatic field control without direct thermal contact, thereby reducing heat loss and power consumption while preserving beam focus quality
2Reliability
If a focus electrode is disposed in direct physical contact with the cathode to suppress side electron emission, then electron beam focus is improved, but electrical short circuit occurs between cathode and focus electrode
Solution Approach 1:
The patent employs an insulating material or vacuum gap as an intermediary between the cathode and focus electrode, enabling the focus electrode to be positioned close to the cathode for effective electrostatic focusing without direct electrical contact. This prevents short circuits while maintaining the electrostatic field necessary for suppressing side electron emission and focusing the beam
3Use of energy by moving object
If the cathode shield is electrically isolated from the cathode to reduce thermal coupling, then heater energy consumption decreases, but electron emission control capability deteriorates
Solution Approach 1:
The patent replaces direct mechanical/thermal contact with electrostatic field interaction. The cathode shield, though electrically isolated via insulating material or vacuum gap, maintains electron emission control capability through electrostatic field effects. This substitution allows thermal decoupling while preserving electrical control function
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
Effectively suppresses side electron emission and reduces heater energy consumption by preventing thermal coupling and maintaining precise electric potential control, thus enhancing the electron gun's performance and reliability.
Implementation Method 1
The cathode 206 is heated by the heater 216 and thereby electrons from cathode 206 emit into a vacuum space
Implementation Method 2
Electrons emitted from a side surface of the cathode 206 are shielded by the cathode shield 221
Data Source
AI summary
To suppress both influence of electron emission from a cathode side surface and consumption of energy to be supplied to a heater, while being provided with a grid, an electron gun of the present invention includes: a cathode capable of emitting electrons by heating; a grid capable of controlling the electron emission; and a cathode shield which is an conductor including a material portion located in the vicinity of a side surface of the cathode and facing at least a portion of the side surface via a gap or a heat insulating material, and not being made in direct physical coupling nor in direct physical contact with the cathode.