Microwave Tube Ion Extraction Device for Cathode Protection
Solution Overview
Problem
Microwave tubes with linear electron beams face issues of ionic relaxation and cathode erosion due to accumulated positive ions, which disrupt RF telecommunications and deteriorate the cathode's emissive surface, and existing solutions like ionic barriers worsen these problems.
Innovation Solution
A device comprising a pair of electrodes, where one electrode is at a negative potential relative to the reference potential, creates an electric field to extract positive ions from the electron beam, redirecting them away from the cathode and into a predetermined surface, thereby preventing erosion and reducing ionic relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an ionic barrier is used to repel positive ions from the cathode, then cathode protection is improved, but ionic relaxation is worsened
Solution Approach 1:
The patent extracts positive ions from the beam before they can accumulate and cause ionic relaxation, while also preventing them from reaching the cathode. The extraction device removes ions from the beam path, directing them away from both the cathode and the main beam volume, thus simultaneously addressing cathode protection and ionic relaxation problems.
Solution Approach 2:
The patent introduces an intermediary extraction device with electrodes that creates an electric field to intercept and redirect positive ions. This intermediary structure prevents ions from directly interacting with both the cathode and the beam, mediating between the ion source and the problematic zones to eliminate both cathode erosion and ionic relaxation effects.
2Object-affected harmful factors
If positive ions are allowed to drift slowly in the beam, then cathode protection is improved, but ionic relaxation is worsened
Solution Approach 1:
Instead of allowing ions to drift slowly in the beam, the patent actively extracts them using an electric field created by the extraction device. The electrodes in the extraction device create a potential that pulls ions out of the beam and redirects them to a safe location, preventing both cathode impact and beam accumulation.
Solution Approach 2:
Rather than relying on the natural slow drift of ions toward the cathode, the patent inverts the approach by using an electric field to pull ions in the opposite direction - away from the cathode and out of the beam. This inversion of the ion transport mechanism simultaneously protects the cathode and prevents ionic relaxation.
3Productivity
If positive ions are extracted using a negative potential electrode, then ion removal efficiency is improved, but device complexity is worsened
Solution Approach 1:
The extraction device is segmented into multiple electrodes with different potentials - a first electrode at reference potential and a second electrode at negative potential. This segmentation creates a controlled electric field region that efficiently extracts ions while confining the complex structure to a localized area, minimizing overall device complexity.
Solution Approach 2:
The patent applies local quality by creating a specialized extraction region with specific electric field characteristics only where needed - between the two electrodes near the beam path. The rest of the device maintains simpler structures, concentrating the complexity only in the local zone where ion extraction is required, thus balancing extraction efficiency with overall device simplicity.
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
Effectively removes positive ions from the electron beam, reducing ionic relaxation and protecting the cathode from ion impacts, allowing for stable RF signal transmission and extended cathode lifespan.
Implementation Method 1
gas molecules present in the vacuum envelope of the tube pass into the beam and lose electrons (ionization phenomenon) under the impact of the electrons of the beam which are very energetic
Implementation Method 2
a device for extracting positive ions comprising at least one electrode e2 brought to a negative potential with respect to the reference potential in order to extract positive ions from the vacuum envelope
Implementation Method 3
The electrons leaving the cathode are focused in the form of a linear beam in the cylindrical vacuum envelope by means of a magnetic field
Data Source
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AI summary
The invention relates to an electronic tube that comprises: a microwave structure (10, 30) having a housing (12, 32) under vacuum and having two ends, the microwave structure being subjected to a reference potential (M); an electron canon (34) including a cathode (36) for providing an electron beam (16, 38) along an axis ZZ' at one end of the housing under vacuum; an electron collector (40) for collecting the beam electrons at the other end of the housing under vacuum; at least one high-voltage power supply for applying a high-voltage potential (HT) to the cathode (36) that is negative relative to the reference potential (M). The tube includes, between the cathode (36) and the microwave structure, a positive-ion extraction device (Pe) that comprises at least one electrode (e2) subjected to a potential (Vp) that is negative relative to the reference potential (M) in order to extract the positive ions (In) from the housing under vacuum, the positive ions being generated by the shock between the electrons of the electron beam and the residual gas molecules in the housing under vacuum. The invention can be used in microwave electronic tubes, TOP klystrons, etc., using a cylindrical electron beam.