Filtered Cathodic Arc Plasma Duct with Offset Deflecting Coils
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Solution Overview
Problem
Vacuum arc coating techniques suffer from the formation of macroparticles that contaminate coatings, leading to irregularities and aesthetic issues, particularly on precision instruments, due to the inability of existing filtering mechanisms to effectively deflect neutral macroparticles away from the substrate.
Innovation Solution
A filtered cathodic arc deposition apparatus with a plasma duct and offset deflecting coils generates a magnetic field to deflect plasma streams towards the substrate, while stream baffles with positive potential intercept and trap macroparticles, enhancing filtration efficiency and reducing plasma losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electromagnetic fields are used to direct plasma stream, then plasma can be directed towards substrate, but macroparticles are not deflected because they are neutral
Solution Approach 1:
The filtering mechanism is segmented into multiple functional zones: an electromagnetic field region for plasma deflection and a mechanical baffle region for macroparticle filtration. This segmentation allows each component to address its specific function - electromagnetic fields direct the plasma stream while mechanical baffles intercept neutral macroparticles that pass through the electromagnetic field.
Solution Approach 2:
A mechanical baffle system is introduced as an intermediary component between the electromagnetic field and the substrate. The baffle acts as a physical mediator that intercepts neutral macroparticles in the plasma stream, preventing them from reaching the substrate while allowing the plasma to be directed by electromagnetic fields toward the substrate.
2Object-affected harmful factors
If simple stationary baffles are used to filter macroparticles, then some macroparticles are trapped, but substantial portion of macroparticles crossing the center area remain untrapped
Solution Approach 1:
The baffle system is made dynamic and adjustable rather than stationary. The baffles can be positioned at different locations and angles within the plasma duct, allowing optimization of their placement to intercept macroparticles effectively while minimizing interference with the plasma stream and maintaining high deposition efficiency.
Solution Approach 2:
The filtering approach is extended from a single-plane baffle to a three-dimensional arrangement of multiple baffles positioned at different locations and orientations within the plasma duct. This multi-dimensional configuration increases the interception capability for macroparticles traveling at different angles while preserving plasma flow paths to the substrate.
3Ease of operation
If plasma duct is configured as quarter section of tore with magnetic system, then plasma stream is directed, but substrate dimension is limited to 200 mm
Solution Approach 1:
The plasma duct is segmented into a modular rectangular configuration with separate sections for plasma generation, electromagnetic deflection, baffle filtration, and substrate deposition. This modular segmentation allows the system to accommodate various substrate sizes and configurations, replacing the fixed geometric constraint of the tore-shaped duct with flexible, reconfigurable components.
Solution Approach 2:
The rectangular plasma duct design with adjustable electromagnetic fields and reconfigurable baffle arrangements creates a universal filtering and deposition system that can handle multiple substrate sizes, shapes, and orientations, rather than being limited to a specific 200 mm dimension as in the tore-shaped configuration.
4Stability of the object's composition
If maximum ionic current at plasma duct exit is limited to one percent of arc current, then turbulence is reduced, but plasma losses on walls increase drastically
Solution Approach 1:
The system replaces reliance on low ionic current (which causes turbulence) with a mechanical filtration approach using baffles. By introducing physical barriers to intercept macroparticles, the system can maintain higher ionic current levels that reduce turbulence and plasma diffusion losses, while the mechanical baffles handle the macroparticle filtration function.
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 solution significantly reduces macroparticle contamination, improving the uniformity and quality of coatings by effectively deflecting plasma streams and trapping macroparticles, thereby increasing deposition efficiency and target utilization rates.
Implementation Method 1
at least one offset deflecting coil, disposed adjacent to a side of the at least one cathode chamber, respectively, and spaced from the plasma duct, that generates a deflecting magnetic field within the at least one cathode chamber
Implementation Method 2
generates a magnetic field to deflect plasma streams towards the substrate
Implementation Method 3
an electric arc is formed between an anode and a cathode plate in a vacuum chamber. The arc generates a cathode spot on a target surface of the cathode, which evaporates the cathode material into the chamber
Implementation Method 4
an electric arc is formed between an anode and a cathode plate in a vacuum chamber
Implementation Method 5
stream baffles with positive potential intercept and trap macroparticles
Implementation Method 6
The cathodic evaporate disperses as a plasma within the chamber
Implementation Method 7
generates a plasma of a vaporized solid material for the application of coatings to surfaces of a substrate by way of condensation of plasma
Data Source
AI summary
An apparatus for generating energetic particles and application of coatings in a vacuum comprising a plasma duct surrounded by a magnetic deflecting and focusing system communicating with a primary cathodic arc plasma source in a cathode chamber and a distal anode in a coating chamber. A coating chamber comprises a substrate holder off of an optical axis of the plasma source. A set of baffles are installed along the walls of cathode chambers and the plasma duct not occupied with plasma sources and in some embodiments across the plasma stream to trap macroparticles and neutrals. A plasma duct has a deflecting portion with attached cathode chamber and a tunnel portion attached to the coating chamber. The deflecting system comprises a deflecting coil surrounding the cathode chamber having an off-set deflecting conductor spaced from the plasma duct. In one embodiment a magnetron source is magnetically coupled with cathodic arc source.