Self-Aligning Filament Clamp Assembly for Ion Source
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Solution Overview
Problem
Existing filament clamp assemblies in ion sources experience compromised electrical connections due to thermal relaxation, requiring frequent repairs and downtime, and are complex to assemble, leading to potential shorts and reduced ion source efficiency.
Innovation Solution
A self-aligning filament clamp assembly with bifurcated clamps and socket head set screws and nuts that securely hold the filament in place, ensuring a consistent gap with the cathode, reducing thermal loss, and simplifying assembly through tapered surfaces for alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional filament clamps with cam operation or setscrew are used, then the filament can be held in place, but the clamping jaws relax over time due to extreme temperatures causing compromised electrical connections
Solution Approach 1:
The clamp assembly is divided into multiple independent clamps (first clamp, second clamp, third clamp, fourth clamp) that can be individually adjusted and replaced. Each clamp has its own setscrew for independent adjustment, allowing one clamp to be serviced without affecting others, thereby maintaining reliable electrical connections over extended periods.
Solution Approach 2:
The clamp assembly incorporates adjustable setscrews (first setscrew, second setscrew, third setscrew, fourth setscrew) that allow dynamic adjustment of clamping force. This enables the operator to compensate for thermal relaxation by tightening the setscrews, maintaining adequate clamping pressure and electrical connection stability despite temperature-induced jaw relaxation.
2Ease of operation
If pan head machine screws are used to attach the filament clamp assembly to the insulator block, then the assembly can be held in place, but improper assembly may result in electric shorts between the filament and cathode
Solution Approach 1:
The traditional mechanical assembly method using pan head machine screws is replaced with a self-aligning clamp design that uses tapered surfaces and set screws to automatically position the filament at the correct height and angle. This eliminates the need for operator skill in positioning while maintaining assembly simplicity through straightforward screw-fastening operations.
Solution Approach 2:
The clamp assembly incorporates self-aligning features including tapered surfaces on the clamps and corresponding tapered bores in the insulator block. When the setscrews are tightened, these tapered surfaces automatically guide the clamps into the correct position, ensuring proper filament alignment and spacing without requiring operator expertise or specialized assembly fixtures.
3Reliability
If the filament is centrally located within the cathode cavity, then ion source performance is optimized, but achieving proper positioning requires operator skill and assembly fixtures
Solution Approach 1:
The clamp assembly is designed with self-aligning tapered surfaces that automatically position the filament at the correct central location within the cathode cavity. When the set screws are tightened, the tapered geometry guides the clamps into the proper position, eliminating the need for operator skill or external assembly fixtures while ensuring optimal ion source performance.
Solution Approach 2:
The tapered surfaces act as intermediary elements between the clamps and the insulator block, providing automatic alignment and positioning functionality. These tapered interfaces translate the simple action of tightening set screws into precise filament positioning, serving as a mechanical intermediary that eliminates the need for complex alignment procedures or specialized fixtures.
4Duration of action of stationary object
If a minimum gap between the filament and cathode is maintained, then ion source life expectancy is maximized, but achieving consistent spacing requires skilled assembly
Solution Approach 1:
The manual positioning method is replaced with a mechanical self-aligning system using tapered surfaces and set screws. This mechanical system automatically maintains the minimum required gap between the filament and cathode by the geometry of the tapered interfaces, ensuring consistent spacing without requiring operator skill or precision measurement during assembly.
Solution Approach 2:
The tapered clamp design provides self-positioning functionality that automatically maintains consistent gap spacing between the filament and cathode. As the set screws are tightened, the tapered surfaces guide the clamps to the correct position, self-regulating the gap distance to ensure optimal ion source life expectancy without requiring external measurement or adjustment.
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 solution provides a secure, repeatable, and self-aligning clamp assembly that reduces downtime, enhances ion source efficiency, and extends filament life by maintaining a precise gap and minimizing heat loss, while being retrofitable to existing ion implanters.
Implementation Method 1
The cathode is heated by an electron bombardment from the filament
Implementation Method 2
the cathode in turn emits electrons thermionically within the arc/plasma chamber
Implementation Method 3
The clamp assembly also has a pair of socket head set screws, each of which is threaded into the threaded bore of a respective clamp and which extends outwardly of the through bore of the respective clamp. The clamp assembly also has a pair of socket head nuts each of which is threaded onto a respective set screw and into abutment with a respective clamp.
Data Source
AI summary
The filament clamp assembly has a pair of bifurcated clamps to hold the connecting leads of a filament within a cavity of a cathode of a separate cathode assembly. The filament clamp assembly is mounted on the insulator block in self-aligning relation. The cathode assembly has a tungsten cathode with an internal cavity to receive the filament that is secured within a retainer shield made of one of tungsten, molybdenum and graphite by a threaded graphite cylindrical collar.