X-ray detector magnetic trap with segmented permanent magnets
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Solution Overview
Problem
Conventional X-ray detectors for electron beam microanalysis face limitations due to the increased distance between the detector and the sample caused by magnetic traps, which also generate a stray magnetic field interfering with the electron beam optics, limiting the solid angle of detection and increasing measurement times.
Innovation Solution
An X-ray detector with a magnetic trap comprising a ring element made of soft magnetic material and multiple permanent magnetic elements arranged in a mosaic fashion along the inner circumference to create a stronger, more homogeneous magnetic field, reducing the overall depth and stray field, allowing closer placement to the sample and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional magnetic trap with two opposing permanent magnets is used, then electrons are deflected laterally and do not reach the detector element, but the distance between the detector and the sample increases and a stray magnetic field interferes with the electron beam optics
Solution Approach 1:
The magnetic trap is segmented into multiple permanent magnets (at least three, preferably four or more) arranged around the inner circumference of the ring element, replacing the conventional two-magnet configuration. This segmentation creates a more distributed magnetic field that achieves effective electron shielding while reducing the overall depth of the trap
Solution Approach 2:
The magnetic field generation transitions from a linear two-magnet arrangement to a circumferential multi-magnet arrangement around the ring element. This dimensional change from a simple opposing-pair configuration to a distributed circular array creates a more homogeneous magnetic field with reduced stray field and decreased trap depth
2Reliability
If a conventional magnetic trap with two opposing permanent magnets is used, then electrons are deflected laterally and do not reach the detector element, but a stray magnetic field emerges beyond the outer circumference and interferes with the electron beam
Solution Approach 1:
The magnetic trap is segmented into multiple permanent magnets (at least three, preferably four or more) arranged around the inner circumference of the ring element, replacing the conventional two-magnet configuration. This segmentation creates a more distributed magnetic field that achieves effective electron shielding while reducing the overall depth of the trap
Solution Approach 2:
The magnetic field distribution is optimized locally by positioning multiple magnets at specific locations around the ring element's inner circumference. This creates a homogeneous magnetic field in the center region where electron shielding is needed, while the field naturally decays and becomes more contained, reducing stray field beyond the outer circumference
3Productivity
If the distance between the detector and the sample is reduced to increase the solid angle of detection, then the detected solid angle increases and measurement time decreases, but the detector structure and electron microscope conditions limit how close the detector can be placed
Solution Approach 1:
The magnetic trap is segmented into multiple permanent magnets (at least three, preferably four or more) arranged around the inner circumference of the ring element, replacing the conventional two-magnet configuration. This segmentation creates a more distributed magnetic field that achieves effective electron shielding while reducing the overall depth of the trap
Solution Approach 2:
The magnetic trap design parameters are changed by increasing the number of permanent magnets from two to at least three, which fundamentally alters the magnetic field distribution. This parameter change results in a shorter required trap depth while maintaining effective electron shielding, enabling the detector to be positioned closer to the sample
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 enhances electron shielding, reduces measurement time, and increases the detected solid angle without increasing the detector's overall depth, while effectively diverting stray magnetic fields, thus improving the electron beam's interference and detection efficiency.
Implementation Method 1
a number N of magnetic elements comprising a permanent magnetic material which are arranged adjacent to one another on the inner circumference of the ring element in such a way that they form a closed ring in a mosaic manner, and whose magnetic orientation direction is selected such that a directed magnetic field is present in the center of the magnetic trap
Implementation Method 2
a ring element made of a soft magnetic material with an inner and an outer circumference
Data Source
Figure 1~2B
Figure 3A~4
AI summary
The invention relates to a low stray field magnetic trap (30) for capturing electrons for an X-ray detector (24), and an X-ray detector (24) comprising the magnetic trap (30), in particular of the EDX type. The magnetic trap (30) according to the invention comprises: (a) a ring element (32) made of a soft-magnetic material with an inner and an outer periphery and (b) a plurality N of magnetic elements (34) comprising a permanent magnetic material, said magnetic elements disposed at the inner periphery of the ring element (32), the magnetic direction of orientation of said magnetic elements being selected such that a magnetic field exists in the center of the magnetic trap (30), wherein the plurality N of magnetic elements (34) numbers at least three and is preferred to be selected according to 2n + 2 with n being a natural number. The magnetic trap (30) according to the invention is characterized by an especially low magnetic stray field and has a very homogeneous and especially strong magnetic field.