Composite Slit Member for High-Purity Multiply Charged Ion Generation
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Solution Overview
Problem
Existing ion generators face challenges in generating high-purity multiply charged ions while suppressing contamination and damage due to electric discharges, especially when operating under conditions that require increased arc voltage or current.
Innovation Solution
The ion generator incorporates a refractory metal material for the inner surface of the arc chamber and graphite for the inner surface of the slit member, combined with a configuration that minimizes the exposure of refractory metal components to the plasma, thereby reducing contamination and electric discharge-related damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arc voltage or arc current is increased to generate sufficient multiply charged ions, then ion generation efficiency is improved, but wear of arc chamber and electric discharge damage increase
Solution Approach 1:
The invention applies different material properties to different parts of the arc chamber: graphite is used for the arc chamber wall that directly contacts plasma (high erosion resistance), while refractory metal is used for the extraction electrode (high melting point and electrical conductivity). This local differentiation allows each component to withstand specific stresses, enabling higher arc power operation without excessive wear or damage.
Solution Approach 2:
The invention employs a composite material strategy by combining graphite and refractory metal in the arc chamber structure. Graphite provides erosion resistance in the plasma environment, while refractory metal provides structural integrity and electrical conductivity for electrode functions. This composite approach resolves the contradiction between generating sufficient multiply charged ions and preventing component wear and damage.
2Productivity
If refractory metal components are exposed to plasma to generate ions, then ion generation capability is improved, but contamination of ion beam increases
Solution Approach 1:
The invention extracts the plasma generation function from the ion extraction function by separating them into different material components. Graphite is dedicated to plasma generation (sacrificial to erosion), while the refractory metal extraction electrode is protected from direct plasma contact. This separation allows ion generation without contamination, as the extraction electrode does not erode into the ion beam.
Solution Approach 2:
Different regions of the arc chamber are assigned different material qualities: graphite in the plasma generation zone (tolerant of erosion) and refractory metal in the extraction zone (requires purity). This local quality differentiation enables the system to generate ions efficiently while preventing contamination of the extracted ion beam.
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 enables the stable generation of high-purity multiply charged ions by minimizing contamination and reducing the risk of electric discharge damage, thus enhancing the operational efficiency and longevity of the ion generator.
Implementation Method 1
a cathode which emits thermoelectrons toward the plasma generation space
Implementation Method 2
an arc chamber which defines a plasma generation space
Data Source
AI summary
An ion generator includes an arc chamber defining a plasma generation space, and a cathode which emits thermoelectrons toward the plasma generation space. The arc chamber includes a box-shaped main body having an opening, and a slit member mounted to cover the opening and provided with a front slit. An inner surface of the main body is exposed to the plasma generation space made of a refractory metal material. The slit member includes an inner member made of graphite and an outer member made of another refractory metal material. The outer member includes an outer surface exposed to an outside of the arc chamber. The inner member includes an inner surface exposed to the plasma generation space, and an opening portion which forms the front slit extending from the inner surface of the inner member to the outer surface of the outer member.