Laminated Electromagnetic Lens for Stable Electron Beam Convergence
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Solution Overview
Problem
Existing electromagnetic lens configurations face challenges in arranging the pole piece close to the electron gun without disturbing the electric field in high potential difference environments, leading to potential electric discharges and aberrations in electron beam convergence.
Innovation Solution
The use of a laminated structure with alternating magnetic material and insulator layers in the pole piece, surrounded by a coil, allows for the pole piece to be positioned closer to the electron gun while minimizing electric field disturbances by voltage-dividing the potential difference and preventing strong electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pole piece is positioned close to the acceleration space in the electron source, then the lens effect on electron beams is improved, but the electric field in the acceleration space is largely disturbed
Solution Approach 1:
The pole piece is divided into multiple segments along its length, with insulating layers positioned between adjacent segments. This segmentation allows the magnetic field to remain continuous while the electric field is blocked at the insulating interfaces, preventing charge accumulation and field distortion in the acceleration space.
Solution Approach 2:
Insulating layers are introduced as intermediary elements between the conductive magnetic material segments of the pole piece. These insulating layers act as mediators that block electric field lines and prevent charge accumulation, allowing the pole piece to be positioned close to the acceleration space without causing electric field disturbance.
2Quantity of substance
If beams with a large divergence angle are used to increase taken current, then the current output is improved, but the aberration becomes large
Solution Approach 1:
The electromagnetic lens provides dynamic and adjustable beam convergence capability. By controlling the coil current, the magnetic field strength can be adjusted to optimize convergence for different beam divergence angles, allowing high current extraction while maintaining beam quality and minimizing aberration.
3Reliability
If an insulator is used to connect the pole piece to the extraction electrode, then electric discharge is prevented, but the electric field in the acceleration space is still disturbed
Solution Approach 1:
The pole piece is segmented into multiple conductive magnetic material sections separated by insulating layers. This segmentation distributes the electric field blocking function throughout the pole piece structure, preventing charge accumulation at any single point and avoiding localized electric field distortion in the acceleration space.
Solution Approach 2:
Multiple insulating layers are positioned at different locations along the pole piece, acting as distributed intermediaries that block electric field lines. This distributed insulation approach prevents electric discharge while minimizing overall electric field disturbance compared to a single insulator connection.
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 effectively suppresses electric field disturbances and prevents electric discharges, enabling the generation of high-brightness electron beams with reduced aberration and improved beam convergence.
Implementation Method 1
an electromagnetic lens includes a coil, and a pole piece configured to include an upper wall, a lower wall, an outer peripheral wall and an inner peripheral wall which are formed using a conductive magnetic material, to surround the coil
Implementation Method 2
the electromagnetic lens is arranged so as to be surrounded by the electromagnetic lens, emit an electron beam, and accelerate the electron beam in a space surrounded by the electromagnetic lens
Data Source
AI summary
An electromagnetic lens includes a coil, and a pole piece configured to include an upper wall, a lower wall, an outer peripheral wall and an inner peripheral wall which are formed using a conductive magnetic material, to surround the coil by the upper wall, the lower wall, the outer peripheral wall and the inner peripheral wall, one of opposite facing surfaces of an upper part and a lower part of the inner peripheral wall and opposite facing surfaces of the upper wall and the inner peripheral wall being insulated electrically, the outer peripheral wall including a laminated structure where a magnetic material and an insulator are alternately laminated in a direction of a central axis of a trajectory of a passing electron beam, and to be covered at least the laminated structure of the outer peripheral wall with an insulator.