Partially Ferromagnetic Duoplasmatron Anode for Negative Ion Extraction
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Solution Overview
Problem
Traditional duoplasmatron ion sources face challenges in producing negative ions due to high electron density exceeding the current capacity of high-voltage power supplies, leading to operational issues and reduced ion beam intensity, as the electron current overloads the power supply and deflects electrons away from the ion extraction aperture.
Innovation Solution
A partially ferromagnetic anode with a ferromagnetic and non-ferromagnetic portion joined at a laterally offset juncture is used to create an asymmetric magnetic field, deflecting electrons and allowing for coaxial alignment of the ion extraction aperture with the Z-electrode aperture, thereby reducing electron transit and enhancing negative ion extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional ferromagnetic anode with a non-ferromagnetic insert is used, then the magnetic field is concentrated at the Z-electrode aperture, but a magnetic hole is created that expands the field and distorts the concentration function
Solution Approach 1:
The anode is designed with non-uniform magnetic properties: a ferromagnetic outer region for field concentration and a non-ferromagnetic central region (ion extraction aperture) to prevent field distortion. This local differentiation resolves the contradiction by assigning different magnetic characteristics to different spatial zones of the same component.
Solution Approach 2:
The anode combines ferromagnetic and non-ferromagnetic materials in a composite structure. The ferromagnetic material provides magnetic field concentration at the Z-electrode aperture, while the non-ferromagnetic central insert prevents magnetic hole formation, achieving both field concentration and uniformity simultaneously.
2Object-generated harmful factors
If the Z-electrode is translated laterally to deflect electrons, then electron extraction is reduced, but the ion extraction aperture cannot be collinearly arranged with the Z-electrode aperture, sacrificing beam intensity
Solution Approach 1:
The anode is segmented into distinct functional regions: a ferromagnetic outer annulus for magnetic field generation and electron deflection, and a non-ferromagnetic central region for ion extraction. This segmentation allows the Z-electrode and ion extraction aperture to be collinearly arranged while still deflecting electrons through the asymmetric ferromagnetic structure.
Solution Approach 2:
The asymmetric ferromagnetic anode structure acts as an intermediary that deflects electrons through magnetic field asymmetry while maintaining coaxial alignment of the Z-electrode and ion extraction aperture. The ferromagnetic material mediates between the need for electron deflection and the need for centralized ion extraction.
3Ease of manufacture
If a non-ferromagnetic anode insert is used, then the ion extraction aperture is defined, but a magnetic hole is created that acts to expand the magnetic field
Solution Approach 1:
The anode employs local quality differentiation by making only the central region where the ion extraction aperture is located non-ferromagnetic, while the surrounding annular region remains ferromagnetic. This localized non-ferromagnetic property defines the aperture without creating a large magnetic hole, maintaining magnetic field concentration.
Solution Approach 2:
The magnetic permeability parameter of the anode is changed spatially: high permeability (ferromagnetic) in the outer region for field concentration, and low permeability (non-ferromagnetic) in the central aperture region. This parameter variation allows aperture definition while controlling magnetic field expansion.
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 increases the extraction of negative ions by up to a factor of 6 and improves beam current density, allowing for more intense and focused ion beams in secondary ion mass spectrometers and particle accelerators.
Implementation Method 1
The partially ferromagnetic anode region has an asymmetric ferromagnetic/non-ferromagnetic construction and is configured to produce an asymmetric magnetic field
Implementation Method 2
a ferromagnetic portion joined with a non-ferromagnetic portion at a juncture that is laterally offset from an ion extraction aperture
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A duoplasmatron ion source with a partially ferromagnetic anode can be used in multiple applications, including the production of negative ions for secondary ion mass spectrometers and particle accelerators. A partially ferromagnetic anode, which may be embodied in a partially ferromagnetic anode insert, includes a ferromagnetic and non-ferromagnetic portions joined together at a juncture, with an ion extraction aperture defined in the ferromagnetic portion and the juncture being laterally offset from the aperture. An asymmetric magnetic field produced by the partially ferromagnetic region facilitates extraction of charged ions from the central, most intense region of a source plasma in the duoplasmatron ion source. A ferromagnetic conical portion of the anode defines the ion extraction aperture in order to maximize the magnetic field in the vicinity of this aperture.