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Investigation & Analysis of Lens-like Effects in Nano Metallic Meshes

Rohani, Ali | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41625 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Rashidian, Bijan; Mehrany, Khashayar
  7. Abstract:
  8. Charged particle lenses perform two types of operations. One purpose of lenses is to confine a beam, or maintain a constant or slowly varying radius. This is important in high-energy accelerators where particles must travel long distances through a small bore.A second function of lenses is to focus beams or compress them to the smallest possible radius. If the particles are initially parallel to the axis, a linear field lens aims them at a common point. Focusing leads to high particle flux or a highly localized beam spot. Focusing is important for applications such as scanning electron microscopy, ion microprobes, and ion-beam-induced inertial fusion. All modern lenses, have fully metal bodies, however it seems that we can have acceptable field distribution by using metallic meshes instead of metal surfaces to design electron lenses with many benefits, such as flexibility and versatility in design. The first part of this thesis is devoted to investigate the modern charged-particle optic devices. In the rest, we have analyzed one hole`s effect on field and potential distribution in space, with step by step approach. To do so, we commenced with finding the effect in a deflector. This approach continued by augmentation of this single hole, to two opposite holes, which is the prime cell of our mesh. After that we investigate the viability of superposing of two adjacent holes as the final step toward our goal of replacing the fully metal bodies with metallic meshes. We analyzed the required specifications (spacing …) in order to have an acceptable behavior. We designed an electron lens based on our unit cell, and at the end, we scaled our device to nano metric scale, and showed its functionality in the nano realm
  9. Keywords:
  10. Electrostatic Lens ; Electron Optical System ; Metallic Meshes ; Nano Mesh

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