Fast Faraday Cup Electrode Design for Charge Density Measurement
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Solution Overview
Problem
Existing Faraday cups for measuring charged particle beams lack the capability to measure the longitudinal distribution of particle charge density with high temporal resolution and are prone to degradation due to the need for biasing voltage circuits.
Innovation Solution
A Fast Faraday Cup design featuring a plurality of electrodes, including a ground electrode with a through hole and a collector electrode with a blind hole, configured in a coaxial cylindrical topology to capture and measure the longitudinal distribution of particle charge density without requiring a biasing voltage, enabling fast response times and wide bandwidth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional Faraday cup design is used, then the device structure is simple, but it cannot measure the longitudinal distribution of particle charge density with high temporal resolution
Solution Approach 1:
The Faraday cup is segmented into multiple electrodes (ground electrode with through hole, collector electrode with blind hole) arranged in a specific configuration. This segmentation allows different regions of the beam to be detected at different positions, enabling measurement of the longitudinal distribution of charge density while maintaining a relatively simple overall structure.
2Reliability
If biasing voltage circuits are used in traditional Faraday cups, then the measurement capability is enhanced, but the device becomes prone to degradation over time
Solution Approach 1:
The biasing voltage circuit is completely removed from the device. Instead of using external biasing to enhance measurement capability, the invention relies on the inherent electrostatic focusing properties of the through-hole and blind-hole electrode configuration, which naturally guides and focuses the charged particle beam without requiring additional voltage circuits, thereby eliminating the degradation issue.
3Loss of time
If the Faraday cup is designed for fast response time, then the time resolution is improved, but the device complexity increases
Solution Approach 1:
The electrodes are designed with specific local geometries (through hole in ground electrode, blind hole in collector electrode) that create localized electric field configurations. These local field structures provide electrostatic focusing and acceleration that inherently enable fast response times with nanosecond time resolution, avoiding the need for complex fast-switching circuits or additional components.
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 Fast Faraday Cup achieves precise measurement of the longitudinal distribution of particle charge density with nanosecond time resolution and captures secondary particles, eliminating the need for biasing circuits while maintaining stable performance.
Implementation Method 1
A Fast Faraday Cup (FFC) that measures the longitudinal distribution of particle charge density in non-relativistic beams... a plurality of electrodes including a ground electrode having a through hole and a collector electrode configured with a blind hole
Data Source
AI summary
A Fast Faraday cup includes a group of electrodes including a ground electrode having a through hole and a collector electrode configured with a blind hole that functions a collector hole. The electrodes are configured to allow a beam (e.g., a non-relativistic beam) to fall onto the ground electrode so that the through hole cuts a beamlet that flies into the collector hole and facilitates measurement of the longitudinal distribution of particle charge density in the beam. The diameters, depths, spacing and alignment of the collector hole and the through hole are controllable to enable the Fast Faraday day cup to operate with a fast response time (e.g., fine time resolution) and capture secondary particles.