Beam density distribution measurement method based on Faraday cup with a micro aperture for high power density electron beams

Li Chen; Qin Zhen; Xiang Jun; Li Tiantao; He Xiaozhong; Xia Liansheng

doi:10.11884/HPLPB202537.240276

Volume 37 Issue 4

Mar. 2025

Turn off MathJax

Article Contents

Article Navigation > High Power Laser and Particle Beams > 2025 > 37(4): 044002

Li Chen, Qin Zhen, Xiang Jun, et al. Beam density distribution measurement method based on Faraday cup with a micro aperture for high power density electron beams[J]. High Power Laser and Particle Beams, 2025, 37: 044002. doi: 10.11884/HPLPB202537.240276

Citation:

Li Chen, Qin Zhen, Xiang Jun, et al. Beam density distribution measurement method based on Faraday cup with a micro aperture for high power density electron beams[J]. High Power Laser and Particle Beams, 2025, 37: 044002. doi: 10.11884/HPLPB202537.240276

Citation:

PDF( 4927 KB)

Beam density distribution measurement method based on Faraday cup with a micro aperture for high power density electron beams

doi: 10.11884/HPLPB202537.240276

Institute of Fluid Physics, CAEP, Mianyang 621900, China

Received Date: 2024-08-26
Accepted Date: 2025-03-14
Rev Recd Date: 2025-03-14

Available Online: 2025-03-26

Publish Date: 2025-04-15

Abstract

Abstract

The electron beam in the electron beam welding machine has the characteristics of high-power density (10⁶−10⁸ W/cm²) and small focal spot size (several hundreds micrometers). Its beam density distribution is an important beam quality parameter and is of great significance to welding process research. However, traditional electron beam density measurement methods, such as fluorescence imaging, cannot be used at such high-power densities. We studied a measurement method based on a combination of a water-cooled Faraday cup with a micro aperture and high-frequency beam scanning. Adding a high-frequency (1−10 kHz) signal to the deflection coil of the electron beam welding machine causes the electron beam to scan within a larger size range, thereby reducing the power density of the electron beam deposited on the surface of the Faraday cup to avoid being burned. Water-cooled Faraday cups that can be used in vacuum chambers are specially designed to take away the heat deposited by the electron beam on the surface of the Faraday cup through water cooling. There is a micro aperture with a size of tens of micrometers on the surface of the Faraday cup. When the electron beam passes through the micro aperture periodically, a small amount of the electron beam passes through the aperture and enters the Faraday cup, forming an electrical signal that is amplified by an amplifier integrated in the Faraday cup and then collected. The electron beam power density distribution can be reconstructed from the collected current signal in the time domain. Experiments have shown that this method can accurately measure the density distribution of high power density electron beams in electron beam welding machines, while having an imaging accuracy of about 23 μm.
- electron beam welding machine,
- high power density beam,
- beam density measurement,
- Faraday cup with a micro aperture

FullText(HTML)

References(16)

References

[1]	Schultz H. Electron beam welding[M]. Cambridge: Woodhead Publishing, 1994.
[2]	Birnie J V. An introduction to electron beam welding[J]. Physics in Technology, 1976, 7(3): 116-122. doi: 10.1088/0305-4624/7/3/I03
[3]	Ahmed N. New developments in advanced welding[M]. Cambridge: Woodhead Publishing, 2005.
[4]	Sun Z, Karppi R. The application of electron beam welding for the joining of dissimilar metals: an overview[J]. Journal of Materials Processing Technology, 1996, 59(3): 257-267. doi: 10.1016/0924-0136(95)02150-7
[5]	Meier J W. Recent advances in electron beam welding technology[J]. Welding Journal, 1963, 42(12): 963-968.
[6]	Arata Y, Tomie M, Terai K, et al. Shape decision of high energy density beam[J]. Transactions of JWRI, 1973, 2(2): 130-146.
[7]	Arata Y. Evaluation of beam characteristics by the AB test method[D]. Ohio/USA: ASM International, 1986.
[8]	Siekman J G, Schoenmakers T M B, Eindhoven K N, et al. New microprobe techniques for measuring the current distribution in an electron beam used for welding[J]. Journal of Physics E: Scientific Instruments, 1975, 8(5): 391-395. doi: 10.1088/0022-3735/8/5/017
[9]	Maternia Z, Radzimski Z, Borkowicz Z. Method of measuring the profile of a fine-focused electron beam by using a semiconductor detector[J]. Journal of Physics E: Scientific Instruments, 1984, 17(6): 447-450. doi: 10.1088/0022-3735/17/6/007
[10]	Wójcicki S, Mladenov G. A new method of experimental investigation of high-power electron beam[J]. Vacuum, 2000, 58(2/3): 523-530.
[11]	Koleva E, Vutova K, Wojcicki S, et al. Use of radial distributions of the beam current density for evaluation of beam emittance and brightness[J]. Vacuum, 2001, 62(2/3): 105-111.
[12]	Dilthey U, Goumeniouk A, Böhm S, et al. Electron beam diagnostics: a new release of the diabeam system[J]. Vacuum, 2001, 62(2/3): 77-85.
[13]	Dilthey U, Boehm S, Dobner M, et al. Comparability, reproducibility and portability of the electron beam technology using new tools of the DIABEAM measurement device[J]. Welding in the World, 1997, 39(3): 124-129.
[14]	Dilthey U, Weiser J. Investigations of EB characteristics and their influences on the weld shape[J]. Welding in the World, 1997, 39(2): 89-98.
[15]	Dilthey U, Weiser J. Study of the tool electron beam-part 1: comparison between the Arata test and Diabeam measurement[J]. Welding Cutting, 1995(47): 339-345.
[16]	Peng Yong, Wang Kehong, Zhou Qi, et al. Beam quality test technology and devices of electron beam welding[J]. Vacuum, 2011, 86(3): 261-266. doi: 10.1016/j.vacuum.2011.06.017