Ion Source Electrode Structure to Suppress Magnetic Field Discharge
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Solution Overview
Problem
Existing ion sources and neutron capture therapy apparatuses face issues with discharge between electrodes due to leaked magnetic fields, leading to damage and increased maintenance frequencies.
Innovation Solution
The ion source and neutron capture therapy apparatus incorporate a plasma electrode with a magnetic first electrode member and a second electrode member having higher melting point and thermal conductivity, designed such that the magnetic field escapes to the outer peripheral side, reducing the generation of leaked magnetic fields and protecting the first electrode member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a magnetic field is applied to generate plasma in the plasma chamber, then ion generation efficiency is improved, but magnetic field leakage causes discharge between electrodes leading to damage and increased maintenance
Solution Approach 1:
A magnetic field shielding member is introduced as an intermediary component between the plasma chamber and extraction electrode. This shielding member intercepts and contains the magnetic field within the plasma chamber, preventing it from leaking to the extraction electrode and causing discharge. The shielding member thus mediates between the plasma generation function and the electrode protection requirement.
Solution Approach 2:
The harmful magnetic field leakage is extracted and isolated from the electrode region by the shielding member. The shielding member effectively removes the magnetic field from the path between plasma chamber and extraction electrode, preventing the discharge phenomenon while maintaining plasma generation.
2Productivity
If the plasma electrode is positioned close to the extraction electrode for efficient ion extraction, then ion extraction efficiency is improved, but discharge between electrodes occurs more frequently causing damage
Solution Approach 1:
The magnetic field shielding member serves as a protective intermediary positioned between the plasma electrode and extraction electrode. It allows the electrodes to maintain close spacing for efficient ion extraction while the shielding member absorbs the magnetic field impact, preventing discharge and protecting the electrodes from damage.
3Productivity
If the plasma chamber is operated at high power for continuous neutron ray emission, then productivity is improved, but heat accumulation causes electrode damage and increases maintenance frequency
Solution Approach 1:
The magnetic field shielding member acts as a thermal intermediary that protects the extraction electrode from direct plasma contact and associated heat loading. By positioning the shielding member between the plasma chamber and extraction electrode, it serves as a thermal barrier that reduces heat accumulation in the extraction electrode, enabling continuous high-power operation.
4Object-affected harmful factors
If the first electrode member is made entirely of magnetic body for magnetic field containment, then magnetic field leakage is reduced, but thermal damage occurs due to low melting point and thermal conductivity
Solution Approach 1:
The first electrode member is constructed as a composite structure combining a magnetic body portion for magnetic field containment and a heat-resistant material portion for thermal protection. This composite design allows the magnetic body to perform its magnetic field shielding function while the heat-resistant material protects against thermal damage from plasma contact and high-power operation.
Solution Approach 2:
The first electrode member is segmented into functionally distinct portions: a magnetic body portion for containing the magnetic field and a heat-resistant material portion for withstanding thermal stress. This segmentation allows each portion to be optimized for its specific function without compromise.
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 design effectively suppresses discharge between electrodes, reducing damage and maintenance frequency, ensuring stable operation and continuous neutron ray emission.
Implementation Method 1
The first electrode member is a magnetic body... a distance of an outer peripheral side end portion of the first electrode member from the extraction opening is equal to or greater than a distance of an outer peripheral side end portion of the extraction electrode from the extraction opening
Implementation Method 2
a plasma chamber in which ions are generated by a plasma
Data Source
AI summary
An ion source includes a plasma electrode that is provided in a plasma chamber in which ions are generated by a plasma; and an extraction electrode that faces the plasma electrode and extracts the ions from the plasma chamber. The plasma electrode includes at least a first electrode member and a second electrode member, and is formed with an extraction opening. The first electrode member is a magnetic body. The second electrode member is a member having at least one of a melting point and thermal conductivity higher than those of the magnetic body. In a second direction perpendicular to a first direction, a distance of an outer peripheral side end portion of the first electrode member from the extraction opening is equal to or greater than a distance of an outer peripheral side end portion of the extraction electrode from the extraction opening.