Field Emitter Current Limiting Against Flashover Damage
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Solution Overview
Problem
Field effect electron emitters in X-ray sources are prone to damage and destruction due to high-voltage flashovers, leading to reduced operating life and potential short circuits.
Innovation Solution
A method involving a first current limiting unit and a gate electrode is used to reduce electron emission by determining the properties of the current path and activating the current limiting unit to manage electron emission, thereby extending the operating life of the electron emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If field effect emitter elements are used to generate electrons, then electron emission efficiency is improved, but susceptibility to high-voltage flashover damage increases
Solution Approach 1:
The emitter array is divided into multiple independently controllable groups or pixels, each with its own current limiting unit. This segmentation allows selective operation of damaged segments while maintaining functionality of undamaged segments, thereby improving reliability without sacrificing overall emission efficiency.
Solution Approach 2:
Current limiting units are pre-integrated into each emitter group before operation begins. These units are configured to limit current flow in advance, preventing catastrophic flashover damage before it occurs. The preliminary setup of protection mechanisms ensures that when flashover does occur, the damage is contained and reversible.
2Productivity
If high current is allowed to flow through emitter elements, then electron emission output is improved, but risk of electrical discharge damage increases
Solution Approach 1:
Current limiting units are configured to automatically restrict current flow when threshold values are approached, providing preliminary anti-action against potential electrical discharge damage. This preemptive current limiting prevents the harmful effects of excessive current while maintaining optimal emission output through controlled operation.
Solution Approach 2:
The current limiting unit acts as an intermediary between the power source and the emitter elements, mediating the current flow to prevent direct exposure of the fragile field effect emitter elements to harmful high currents. This intermediary component protects the emitters while still allowing sufficient current for high output emission.
3Device complexity
If no current limiting is implemented, then device complexity is reduced, but operating life of emitter elements decreases
Solution Approach 1:
The current limiting functionality is merged directly into the emitter structure by integrating current limiting units with each emitter group. This combination approach adds protection functionality without significantly increasing overall device complexity, as the limiting units share physical and electrical integration with the emitter elements they protect.
Solution Approach 2:
Each emitter group includes its own current limiting unit, enabling self-protection and self-regulation of current flow. This self-service approach allows the emitter system to automatically protect itself from damage without requiring external monitoring or control systems, thereby extending operating life while maintaining relatively simple device architecture.
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
The method effectively reduces electron emission, allowing continued operation with minimal damage, particularly beneficial for pixelated or segmented emitters, and includes self-healing capabilities to prevent further damage.
Implementation Method 1
Cold electron emitters emit electrons in particular without comparable heating, but rather according to the field effect, for example, via field effect emitter elements set up for this purpose
Implementation Method 2
emission of electrons from the first current path via the at least one first field effect emitter element, subject to an emission voltage between the gate electrode and the emission surface
Implementation Method 3
activation of the first current limiting unit subject to the determined properties of the first current path for reducing the electron emission of the electron emitter
Data Source
AI summary
A method for reducing electron emission of an electron emitter comprises: emitting electrons from a first current path via at least one first field effect emitter element, subject to an emission voltage between a gate electrode and an emission surface; determining a property of the first current path; and activating a first current limiting unit subject to the properties of the first current path to reduce the electron emission of the electron emitter.