## This content will become publicly available on May 14, 2020

## Low-energy high-brightness electron beam dynamics based on slice beam matrix method

## Abstract

Preserving the phase space quality has been of crucial importance to high-brightness electron beam transport. Any driving source of beam performance limitations in such a transport system must be carefully examined in order to preserve the beam phase space quality. It is found that in the low beam energy, high bunch charge regime, space charge effect on the charged particle beam evolution can be complicated. It may be insufficient to analyze the beam properties through the envelope or lower order moments for the mere bulk of the beam. In this work we will study the space-charge-dominated, low-energy, high-brightness electron beam dynamics based on the slice beam matrix method. The slice beam matrix method, extended from the existing bulk beam analysis, is applicable to an arbitrary longitudinal bunch distribution and can thus take the nonlinear RF curvature into account. The semi-analytical sliced beam space charge model is constructed and assumes an axisymmetric beam in the presence of perfect conducting cylindrical pipe with circular cross section. We present in this paper the theoretical formulation, starting from single-particle dynamics, space charge field calculation, followed by the moment description of a collection of particles, based on beam sigma matrix and longitudinal slice decomposition. Wemore »

- Authors:

- Huazhong Univ. of Science and Technology, Wuhan (China); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Huazhong Univ. of Science and Technology, Wuhan (China)
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Institute of High Energy Physics, Chinese Academy of Sciences, and Univ. of Chinese Academy of Sciences, Beijing (China)
- Stony Brook Univ., Stony Brook, NY (United States)

- Publication Date:

- Research Org.:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1532408

- Grant/Contract Number:
- 5003131049; AC02-76SF00515; FWP-2013-SLAC-100164

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

- Additional Journal Information:
- Journal Volume: 937; Journal Issue: C; Journal ID: ISSN 0168-9002

- Publisher:
- Elsevier

- Country of Publication:
- United States

- Language:
- English

- Subject:
- High-brightness electron beam; Space charge dynamics; Beam matrix method; Slice analysis; Semi-analytical calculation

### Citation Formats

```
Tsai, Cheng -Ying, Fan, Kuanjun, Feng, Guangyao, Wu, Juhao, Zhou, Guanqun, and Wu, Yuan Hui. Low-energy high-brightness electron beam dynamics based on slice beam matrix method. United States: N. p., 2019.
Web. doi:10.1016/j.nima.2019.05.035.
```

```
Tsai, Cheng -Ying, Fan, Kuanjun, Feng, Guangyao, Wu, Juhao, Zhou, Guanqun, & Wu, Yuan Hui. Low-energy high-brightness electron beam dynamics based on slice beam matrix method. United States. doi:10.1016/j.nima.2019.05.035.
```

```
Tsai, Cheng -Ying, Fan, Kuanjun, Feng, Guangyao, Wu, Juhao, Zhou, Guanqun, and Wu, Yuan Hui. Tue .
"Low-energy high-brightness electron beam dynamics based on slice beam matrix method". United States. doi:10.1016/j.nima.2019.05.035.
```

```
@article{osti_1532408,
```

title = {Low-energy high-brightness electron beam dynamics based on slice beam matrix method},

author = {Tsai, Cheng -Ying and Fan, Kuanjun and Feng, Guangyao and Wu, Juhao and Zhou, Guanqun and Wu, Yuan Hui},

abstractNote = {Preserving the phase space quality has been of crucial importance to high-brightness electron beam transport. Any driving source of beam performance limitations in such a transport system must be carefully examined in order to preserve the beam phase space quality. It is found that in the low beam energy, high bunch charge regime, space charge effect on the charged particle beam evolution can be complicated. It may be insufficient to analyze the beam properties through the envelope or lower order moments for the mere bulk of the beam. In this work we will study the space-charge-dominated, low-energy, high-brightness electron beam dynamics based on the slice beam matrix method. The slice beam matrix method, extended from the existing bulk beam analysis, is applicable to an arbitrary longitudinal bunch distribution and can thus take the nonlinear RF curvature into account. The semi-analytical sliced beam space charge model is constructed and assumes an axisymmetric beam in the presence of perfect conducting cylindrical pipe with circular cross section. We present in this paper the theoretical formulation, starting from single-particle dynamics, space charge field calculation, followed by the moment description of a collection of particles, based on beam sigma matrix and longitudinal slice decomposition. We prove the equivalence between the beam matrix method and the envelope formalism in the presence of space charge effect, in both the transverse and longitudinal dimensions. Two examples are then demonstrated, one for a unit cell of superconducting radio-frequency (RF) cavity and the other for a 1.5-cell RF gun system. The semi-analytical results from beam matrix calculation are discussed and compared with particle tracking simulation using ASTRA. In conclusion, we expect that the analysis based on the slice beam matrix method shall serve as an efficient and advanced tool to further investigate the low-energy high-brightness electron beam dynamics.},

doi = {10.1016/j.nima.2019.05.035},

journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},

number = C,

volume = 937,

place = {United States},

year = {2019},

month = {5}

}