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Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization
Published on: July 12, 2016
Nature of the decrease of the secondary-electron yield by electron bombardment and its energy dependence.
R Cimino1, M Commisso, D R Grosso
1LNF-INFN, Frascati (Roma), Italy.
Physical Review Letters
|September 26, 2012
Summary
Electron bombardment of copper surfaces in particle accelerators causes chemical changes, reducing secondary electron yield (SEY). Lower energy electrons cause slower SEY reduction, impacting accelerator operations.
Area of Science:
- Materials Science
- Surface Science
- Accelerator Physics
Background:
- Technical surfaces in particle accelerators like the Large Hadron Collider (LHC) are subject to electron bombardment.
- Secondary electron yield (SEY) is a critical parameter affecting accelerator performance and stability.
- Understanding surface modifications under electron irradiation is essential for optimizing accelerator operations.
Purpose of the Study:
- To investigate the chemical modifications of a representative LHC technical surface under electron bombardment.
- To study the relationship between electron dose, energy, and the resulting secondary electron yield (SEY).
- To analyze the impact of primary electron energy on surface graphitization and SEY reduction.
Main Methods:
- Combined secondary electron yield (SEY) measurements and X-ray photoelectron spectroscopy (XPS).
- Controlled electron bombardment of a copper (Cu) technical surface.
- Systematic variation of electron dose and primary electron kinetic energy (E).
Main Results:
- Electron bombardment leads to significant chemical modification of the Cu surface, characterized by increased graphitization.
- A decrease in SEY was observed, correlating with the extent of graphitization.
- The rate and magnitude of SEY reduction were dependent on primary electron energy; lower energies (E≤20 eV) resulted in slower and smaller reductions compared to higher energies.
Conclusions:
- Electron-induced graphitization alters the surface properties and reduces the secondary electron yield (SEY) of LHC-like surfaces.
- The energy of primary electrons plays a crucial role in the kinetics of surface modification and SEY reduction.
- Findings have direct implications for the commissioning and operational scenarios of the LHC and other particle accelerators.
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