Movable Emitter Support for Stable Field Emission Positioning
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Solution Overview
Problem
In field emission devices like X-ray apparatuses, tolerances in component dimensions and assembly can lead to unintended gaps between the electron generating portion of the emitter and the guard electrode, preventing desired field emission and potentially causing X-ray dispersion.
Innovation Solution
The use of a movable emitter supporting unit with a bellows and a pressing shaft allows for precise adjustment and contact between the electron generating portion of the emitter and the guard electrode, enabling desired field emission by moving the emitter from a no-discharge region to a dischargeable region and applying voltage for regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed emitter supporting unit is used, then the structure is simple, but the electron generating portion cannot be precisely positioned to contact the guard electrode, causing flashover and unstable electron beam emission
Solution Approach 1:
The emitter supporting unit is designed to be movable rather than fixed, allowing the electron generating portion to be precisely positioned and brought into contact with the guard electrode. This dynamic adjustment capability ensures stable electron beam emission by eliminating flashover caused by improper positioning, while the simplicity of the movable structure (using basic components like springs and positioning mechanisms) keeps the overall device complexity low.
2Manufacturing precision
If the electron generating portion is positioned too far from the guard electrode, then flashover is suppressed, but the electron beam disperses and X-ray resolution deteriorates
Solution Approach 1:
The system incorporates a positioning mechanism that allows precise adjustment of the distance between the electron generating portion and the guard electrode. By enabling fine-tuned positioning, the system can optimize the gap to prevent flashover while maintaining sufficient proximity to ensure focused electron beam emission and high X-ray resolution. The movable supporting unit provides the necessary adjustment range and precision.
3Ease of manufacture
If tolerance in component dimensions and assembly is not controlled, then manufacturing is easier, but unintended gaps form between the electron generating portion and guard electrode, preventing desired field emission
Solution Approach 1:
The movable emitter supporting unit compensates for dimensional tolerances and assembly variations by allowing post-assembly positioning adjustments. This dynamic capability ensures that even with standard manufacturing tolerances, the electron generating portion can be precisely positioned relative to the guard electrode to achieve the desired field emission performance, eliminating the need for extremely tight tolerance control.
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 configuration ensures that the electron generating portion and the guard electrode can be brought closer or into contact, stabilizing the electron beam emission and preventing flashover, thus achieving focused X-ray irradiation with improved resolution.
Implementation Method 1
bellows having a tubular shape having a larger diameter than the emitter supporting unit female screw bore and expanding and contracting in the both end directions
Implementation Method 2
an emitter supporting unit operation hole (a reference sign 32 in FIGS. 1 and 2) penetrating an inner circumferential side of the bellows in the both end directions at the one side in the both end directions of the vacuum enclosure and extending in the both end directions so that an axis of the emitter supporting unit operation hole is arranged coaxially with the screw bore of the emitter supporting unit female screw bore
Implementation Method 3
the pressing shaft has, at a tip thereof, a tip surface having a larger diameter than an opening diameter of the emitter supporting unit female screw bore and extending along a radial direction of the pressing shaft
Implementation Method 4
by applying voltage between these emitter and target, an electron beam is emitted by field emission (by generation of electrons and emission of the electrons) of the emitter
Implementation Method 5
by colliding the emitted electron beam with the target, a desired function (for instance, in the case of the X-ray apparatus, a radioscopy resolution by external emission of X-ray) is obtained
Implementation Method 6
by arranging a guard electrode, which is at the same potential as the emitter, at an outer circumferential side of the emitter
Data Source
AI summary
Opening edge surface (45a) of an emitter supporting unit female screw bore (45) provided at an emitter supporting unit (4) extends along radial direction of the emitter supporting unit female screw bore (45). An emitter supporting unit operation hole (32) provided at a flange portion (30a) of a vacuum enclosure (11) has shape into which one selected from a position adjustment shaft (6) and a pressing shaft (9) can be inserted from their shaft tip sides. The position adjustment shaft is provided, on an outer circumferential surface of its tip (61), with a tip side male screw portion (61a) that can be screwed into the emitter supporting unit female screw bore (45). The pressing shaft has, at its tip (91), a tip surface (91a) having a larger diameter than an opening diameter of the emitter supporting unit female screw bore (45) and extending along radial direction of the pressing shaft.