Electron Gun Astigmatism Correction Using Split Rogowski Coil Feedback
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Solution Overview
Problem
The existing anastigmatic devices in electron beam machining equipment have high randomness and difficulty in reaching the optimum state for correcting electron beam spot morphology, especially in high-power equipment, due to disalignment of electron beams and heterogeneous pole piece materials, leading to astigmatism and inconsistent focusing.
Innovation Solution
An automatic anastigmatic electron gun system with a central controller, electronic source power supply, drive power supply, electron beam generator, anastigmatic device, and a detection device with non-magnetic conductive insulation material framework, which uses a signal processing circuit to automatically adjust the exciting current of the anastigmatic windings based on real-time detection of electron beam spot morphology, ensuring optimal correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional anastigmatic operation based on empirical method is used, then the operation is simple, but the correction effect has high randomness and is difficult to reach the optimum state
Solution Approach 1:
The patent implements automatic anastigmatic control by introducing a feedback mechanism where the detection device monitors electron beam spot morphology and the central controller adjusts the anastigmatic device based on detected information, replacing empirical methods with closed-loop control to eliminate randomness and achieve optimal correction consistently
Solution Approach 2:
The patent replaces the manual empirical adjustment method with an automated control system that uses detection devices and central controllers to automatically adjust the anastigmatic device, substituting human experience-based operation with instrumented measurement and automatic control
2Manufacturing precision
If micro electron beams are used for correction, then the correction can be performed, but the electron beam power is much smaller than machining beam and correction effect is limited
Solution Approach 1:
The patent uses the actual machining electron beam parameters (voltage, current, focus) to generate a copy of the machining beam conditions for the correction process, allowing the correction to be performed under identical beam conditions as the actual machining, thereby eliminating the limitation of using reduced-power micro beams
3Productivity
If non-contact detection device is used, then the detecting element can be reused and meet production requirements, but the detection system becomes more complex
Solution Approach 1:
The patent introduces a non-contact detection device as an intermediary between the electron beam and the measurement system, using magnetic field detection through detection windings that sense the electron beam's magnetic field without physical contact, thereby enabling reusable detection that meets production requirements while maintaining system integrity
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 system achieves precise and consistent correction of electron beam spot morphology by using actual machining electron beam values for correction, automatically determining the optimal exciting current for the anastigmatic device, thereby improving the effectiveness and reliability of electron beam machining processes.
Implementation Method 1
the anastigmatic device comprises anastigmatic windings with two phases, which form a structure with a plurality of pairs of axisymmetrical magnetic poles
Implementation Method 2
the detection device comprises a framework and four detection windings; the four windings have the same number of turns and the same wire diameter, and are wound around the framework
Data Source
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AI summary
The present invention discloses an automatic anastigmatic electron gun and an automatic anastigmatic method for an electron gun, which use a split Rogowski coil as the detecting element to realize non-contact detection of electron beam spot morphology in combination with the pulse electron beam technology. The split Rogowski coil uses differential-mode signals as the output and the minimum value of detection signals as the correction target of the anastigmatic device, which simplifies the processing method of detection signals, eliminates the influence of common-mode interference signals, and improves detection sensitivity and precision. The "optimum" exciting current of the anastigmatic device is searched by axes to realize quick search. The weighted values of the amplitude and the average value of the detection signals can reflect the difference of electron beam spot morphology more fully. With the integrated data of the weighted values as the judgment basis, two rounds of search and confirmation of the "optimum" value further improve the reliability and reduce the randomness.