Filament-Less Electron Source With Joule-Heated Crystal Supports
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Solution Overview
Problem
Electron sources with wire filaments are inefficient at high temperatures due to significant thermal expansion and excess heat loss, requiring improved designs to reduce operational power and thermal conduction.
Innovation Solution
The electron source crystal is coupled in series with electrically conductive supports, where Joule heating occurs primarily within the crystal, reducing reliance on filament heat generation, and using foil supports with higher resistance than the crystal to direct current flow through the crystal legs, thereby minimizing thermal expansion and heat loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a wire filament is used to heat the electron emitter crystal, then the crystal can reach high emission temperatures, but significant thermal expansion and excess heat loss occur
Solution Approach 1:
The patent extracts the heating function from a separate wire filament and relocates it directly to the electron emitter crystal. By forming conductive supports that conduct current through the crystal itself, the heating function is taken out of the traditional filament structure and integrated into the crystal, eliminating thermal conduction losses to support structures.
Solution Approach 2:
The electron emitter crystal serves dual functions: it is both the heating element and the electron emission source. By conducting current directly through the crystal via the conductive supports, the crystal heats itself (self-service) rather than being heated by an external filament, improving thermal efficiency and reducing energy loss.
2Temperature
If a wire filament is used to heat the electron emitter crystal, then the crystal can reach high emission temperatures, but significant thermal expansion occurs
Solution Approach 1:
The patent removes the separate wire filament structure that causes thermal expansion instability. By integrating the heating function directly into the crystal through conductive supports, the system eliminates the mechanical interface between filament and crystal that generates thermal expansion issues.
Solution Approach 2:
The conductive supports are designed with specific electrical resistance properties to concentrate Joule heating locally within the crystal volume. This localized heating approach creates more uniform temperature distribution within the crystal, reducing thermal gradients and associated thermal expansion instability.
3Use of energy by stationary object
If wire filament dimensions and material are changed to reduce power consumption, then operational power can be lowered, but mechanical properties are limited
Solution Approach 1:
The patent replaces the mechanical wire filament system with an electrical conduction system through conductive supports. Instead of relying on mechanical filament properties (dimensions, material strength), the system uses electrical resistance properties of the supports to control heating, substituting mechanical design constraints with electrical design flexibility.
Solution Approach 2:
The conductive supports are designed with specific electrical resistance parameters to optimize Joule heating efficiency. By controlling the electrical resistance of the supports, the system can regulate power consumption and heating efficiency without being constrained by mechanical filament properties, allowing independent optimization of electrical and mechanical parameters.
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 achieves lower operational power consumption, reduced thermal expansion, and improved thermo-mechanical stability, extending emitter lifetime and maintaining a stable vacuum environment.
Implementation Method 1
Joule heating occurs primarily within the crystal, reducing reliance on filament heat generation
Implementation Method 2
During operation of the source, the filament is heated, an electrostatic potential is applied between the emitter crystal and the adjacent anode, and the work function of the emitting surface on the emitter crystal is lowered with the application of ZrO. Due to the temperature increase and the lowered work function, emission of electrons from the crystal tip rapidly increases, thereby generating the electron source beam.
Data Source
AI summary
Electron sources can include an electron source crystal coupled in series between opposing electrically conductive supports to form an electrically conductive path, wherein the electrical resistance of each of the electrically conductive supports is lower than the electrical resistance of the electron source crystal. Electron source crystals can include an emitting end and opposing shank end, wherein the shank end includes opposing leg portions. Electrically conductive supports can include foil supports spaced apart across a gap, wherein each of the opposing leg portions is attached to a respective foil support such that the foil supports are electrically connected to form the electrically conductive path. Particle focusing system are also disclosed. Electron sources can include an electron source crystal having an emitting end and opposing shank end, wherein the shank end is formed of a pair of opposing leg portions. Methods of manufacturing and operating electron sources are also disclosed.