X-ray Tube Ion Barrier Electrode Design
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Solution Overview
Problem
X-ray tubes suffer from premature emitter failure due to ion bombardment from residual gas ionization, leading to focal spot instability and reduced useful life, with existing ion barriers increasing complexity and cost.
Innovation Solution
A ring-like ion barrier electrode is positioned between the cathode and anode, energized with a positive voltage bias to repel positively charged ions, maintaining them within the drift region and minimizing damage to the emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a grid electrode is used to control electron flow and shut off the electron beam, then electron beam control is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the grid electrode from the X-ray tube design. Instead of using a grid electrode to control electron flow, the invention relies on the natural electrostatic field between the cathode and anode, combined with ion barrier electrodes positioned away from the electron beam path. This removal simplifies the device structure while maintaining beam control capabilities through alternative means.
2Adaptability or versatility
If the electron beam drifts a longer distance past the anode, then electron beam manipulation is improved, but ion generation increases
Solution Approach 1:
The patent introduces ion barrier electrodes as intermediary elements positioned in the electron drift region. These electrodes create local electric fields that deflect and control ions generated during the extended electron beam drift, preventing them from reaching the cathode. This allows the system to maintain long drift paths for beam manipulation while mitigating the harmful effects of increased ion generation.
3Reliability
If an ion barrier is added to protect the emitter from ion bombardment, then emitter reliability is improved, but device complexity increases
Solution Approach 1:
The patent positions ion barrier electrodes in a spatial configuration that is distinct from the electron beam path. The electrodes are placed in the drift region away from the center where electrons travel, creating a three-dimensional arrangement where ion protection and electron transmission occur simultaneously. This dimensional separation allows ion barrier functionality to be added without significantly increasing device complexity or interfering with electron beam operation.
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 ion barrier effectively extends the useful life of the X-ray tube by reducing emitter damage and stabilizing the focal spot without significantly increasing complexity or cost, by maintaining a positive potential barrier across the ion barrier electrode.
Implementation Method 1
The ion barrier electrode is energized with a positive voltage bias to repel positively charged ions
Implementation Method 2
maintaining a positive potential barrier across the ion barrier electrode
Implementation Method 3
The electron emission originating from the surface of a thermoionic electron emitter
Implementation Method 4
When electrons generated by the emitters and drawn towards the anode strike the residual gas, the gas becomes ionized
Data Source
AI summary
In the present invention, a cathode is formed with one or more emitters energized to emit electrons that are accelerated towards an anode or target spaced from the cathode. Between the cathode and the target is disposed an ion barrier electrode defining an aperture therein disposed in alignment with the emitters to enable the electron beam to pass through the electrode. The barrier electrode is operably connected to a voltage supply to positively bias the barrier electrode, and the barrier electrode is shaped to minimize the required supply voltage. This positive voltage bias creates a positive potential barrier across the electrode sufficient to repel positive ions generated by the electron beam, protecting the cathode from contact with the ions and increasing the stability of the focal spot generated by the tube by maintaining the ions within the drift region between the ion barrier and the target.