Electron Gun Cathode Assembly With Thermal Barrier Geometry
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Solution Overview
Problem
Existing electron gun cathodes are expensive and prone to thermal energy loss, resulting in poor beam quality and contamination issues due to the difficulty in achieving a reliable thermal barrier between the emitting member and the carrier, which are often made of different materials.
Innovation Solution
A cathode assembly with a thermal barrier between the carrier and holder, featuring a smaller contact area and specific geometries such as ridges and grooves, reduces heat transfer and allows for external heating of the emitting member or carrier to maintain the emitting member at a high temperature with reduced energy input, using materials with lower work functions to enhance electron emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the carrier and holder are made of different materials to achieve reliable thermal barrier, then thermal energy transfer is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies homogeneity by making both the carrier and holder from the same material (tungsten), eliminating material incompatibility issues. The thermal barrier is achieved not through material differentiation but through geometric design - specifically a reduced contact area between carrier and holder, which maintains thermal isolation while simplifying manufacturing processes and material selection.
2Loss of energy
If the contact area between carrier and holder is reduced to minimize heat transfer, then thermal energy loss is reduced, but mechanical stability and reliability decrease
Solution Approach 1:
The patent applies local quality by creating a non-uniform contact area between carrier and holder. The contact interface is designed with specific local characteristics - a reduced contact area at the carrier-holder interface compared to other interfaces. This localized geometric modification achieves thermal isolation while maintaining adequate mechanical stability through carefully designed contact geometry rather than reducing contact throughout the entire structure.
3Use of energy by moving object
If external heating is used to heat the emitting member, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The patent applies the intermediary principle by using the carrier as a thermal mediator. The carrier serves dual functions: it provides mechanical support for the emitting member and acts as a thermal pathway from the external heat source to the emitting member. This intermediary approach allows external heating to efficiently transfer thermal energy to the emitting member without requiring direct heating mechanisms, reducing overall system complexity while maintaining low energy consumption.
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 design reduces energy consumption and cooling requirements, allows for the use of cheaper materials, and improves beam quality by minimizing heat loss and contamination, resulting in a more efficient and cost-effective cathode assembly for applications like 3D printing and electron microscopes.
Implementation Method 1
the emitting member emits charged particles from an emitting surface at an emitting temperature
Implementation Method 2
the cathode is heated by irradiation from an external source
Implementation Method 3
the connection between said carrier and said holder provides a thermal barrier for reducing the amount of thermal energy transferred from the cathode to the holder
Data Source
AI summary
A cathode assembly for emitting charged particles, used in for example an electron gun as source for generating an electron beam is provided. The cathode assembly has a cathode including an emitting member and a carrier. The emitting member is mounted in the carrier, and the carrier is electrically connected to a holder. The cathode is heated by irradiation from an external source, whereby the emitting member emits charged particles from an emitting surface at an emitting temperature. The connection between the carrier and the holder provides a thermal barrier for reducing the amount of thermal energy transferred from the cathode to the holder.