Nano-projection Cathode Ion Source for Stable Field Emission
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Solution Overview
Problem
Ion sources used in neutron generators for well logging instruments suffer from power consumption issues due to ohmic heating and emit electrically conductive particles that can degrade performance by altering the electric field and causing arcing, leading to reduced ion beam accuracy and instrument lifespan.
Innovation Solution
An ion source design featuring a cathode with an electrically conductive substrate and insulating layer with nano-sized projections and gates, creating a voltage difference for field emission and ionization without ohmic heating, reducing power consumption and minimizing the emission of conductive particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ohmic heating is used in the cathode, then stable and copious electron generation is achieved, but power consumption becomes undesirably large
Solution Approach 1:
The patent replaces the thermal field (ohmic heating) with an electric field (field emission) to generate electrons. The cathode structure uses nano-sized projections with high electric field concentration at their tips, enabling electron emission through quantum tunneling without requiring thermal heating, thus eliminating the power consumption issue while maintaining stable electron generation.
Solution Approach 2:
The patent changes the emission mechanism parameter from thermal emission to field emission. By designing the cathode with nano-sized projections having specific geometric parameters (sharp tips, small radius of curvature), the electric field strength at the tip is sufficiently high to induce field emission, fundamentally changing how electrons are generated and eliminating the need for ohmic heating.
2Productivity
If conventional cathodes are used, then electron emission is achieved, but electrically conductive particles are emitted and build up on insulating surfaces
Solution Approach 1:
The patent extracts and eliminates the harmful byproduct (conductive particle emission) from the electron generation process. By using field emission from nano-projections, the electron source becomes a controlled quantum mechanical process that does not involve material sputtering or evaporation, thereby removing the source of conductive particles while maintaining electron emission capability.
Solution Approach 2:
The patent replaces the thermal-mechanical emission process with a pure electric field process. Field emission is a quantum mechanical phenomenon that occurs without physical contact or thermal stress, eliminating the mechanical processes that would otherwise cause material degradation and particle emission.
3Reliability
If conductive particles build up on insulating surfaces, then the electric field characteristics are altered, but ion beam focal point accuracy is reduced
Solution Approach 1:
The patent takes preliminary action to prevent the formation of conductive particle deposits on insulating surfaces. By eliminating the source of conductive particles through field emission, the problem of particle accumulation and subsequent electric field distortion is prevented before it can occur, maintaining both electric field stability and ion beam accuracy.
4Productivity
If conventional cathodes are used, then ion source operation is maintained, but electrical arcing occurs between electrodes due to insulator failure
Solution Approach 1:
The patent converts the potential harm of high electric fields (which could cause breakdown) into a beneficial field emission process at the cathode. The high electric field is localized and controlled at the nano-projection tips for electron emission, while the overall field distribution is designed to prevent breakdown at insulator locations, thus preventing arcing while maintaining operation.
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 design reduces power consumption, minimizes the emission of electrically conductive particles, and enhances the accuracy and longevity of neutron generators by maintaining a stable electric field and preventing arcing, thus improving the performance and lifespan of well logging instruments.
Implementation Method 1
The array of nano-sized projections and the array of gates may have a first voltage difference such that a resultant electric field between respective projections and gates causes electrons to be emitted from the array of nano-sized projections and accelerated away from the at least one cathode
Implementation Method 2
some of the electrons as they travel within the ion source electrode striking an ionizable gas to create ions
Data Source
AI summary
An ion source for use in a particle accelerator includes at least one cathode. The at least one cathode has an array of nano-sized projections and an array of gates adjacent the array of nano-sized projections. The array of nano-sized projections and the array of gates have a first voltage difference such that an electric field in the cathode causes electrons to be emitted from the array of nano-sized projections and accelerated downstream. There is a ion source electrode downstream of the at least one cathode, and the at least one cathode and the ion source electrode have the same voltage applied such that the electrons enter the space encompassed by the ion source electrode, some of the electrons as they travel within the ion source electrode striking an ionizable gas to create ions.