# Wake loss and energy spread factor of the LEReC Booster cavity caused by short range wake field

## Abstract

LEReC project uses a DC photoemission gun with multi-alkali (CsK _{2}Sb or NaK _{2}Sb) cathode [1]. To get 24 mm “flat-top” distribution, 32 Gaussian laser bunches with 0.6 mm rms length are stacked together with 0.75 mm distance [2]. In this case one cannot simply use a 1 cm rms length Gaussian/step/delta bunch for short range wake field simulation since a 0.6 mm bunch contains frequency much higher than the 1 cm bunch. A short range wake field simulation was done using CST Particle Studio™ with 0.6 mm rms Gaussian bunch at the speed of light, and this result was compared with the result for 1 cm rms Gaussian bunch in Figure 1, from where one notice that the wake potential for the 0.6 mm bunch is ~10 times higher than that of the 1 cm bunch. The wake potential of the 0.6 mm bunch, as well as the charge distribution, was then “shift and stack” every 0.75 mm, the normalized results are shown in Figure 2. The wake loss factor (WLF) is the integration of the product of wake potential and normalized bunch charge, and the energy spread factor (ESF) is the rms deviation from the average energy loss.more »

- Authors:

- Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

- Publication Date:

- Research Org.:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)

- OSTI Identifier:
- 1436272

- Report Number(s):
- C-A/AP/598; BNL-203601-2018-TECH

- DOE Contract Number:
- SC0012704

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 43 PARTICLE ACCELERATORS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

### Citation Formats

```
Xiao, Binping, Blaskiewicz, Michael, Fedotov, Alexei, and Xin, Tianmu.
```*Wake loss and energy spread factor of the LEReC Booster cavity caused by short range wake field*. United States: N. p., 2018.
Web. doi:10.2172/1436272.

```
Xiao, Binping, Blaskiewicz, Michael, Fedotov, Alexei, & Xin, Tianmu.
```*Wake loss and energy spread factor of the LEReC Booster cavity caused by short range wake field*. United States. doi:10.2172/1436272.

```
Xiao, Binping, Blaskiewicz, Michael, Fedotov, Alexei, and Xin, Tianmu. Mon .
"Wake loss and energy spread factor of the LEReC Booster cavity caused by short range wake field". United States.
doi:10.2172/1436272. https://www.osti.gov/servlets/purl/1436272.
```

```
@article{osti_1436272,
```

title = {Wake loss and energy spread factor of the LEReC Booster cavity caused by short range wake field},

author = {Xiao, Binping and Blaskiewicz, Michael and Fedotov, Alexei and Xin, Tianmu},

abstractNote = {LEReC project uses a DC photoemission gun with multi-alkali (CsK2Sb or NaK2Sb) cathode [1]. To get 24 mm “flat-top” distribution, 32 Gaussian laser bunches with 0.6 mm rms length are stacked together with 0.75 mm distance [2]. In this case one cannot simply use a 1 cm rms length Gaussian/step/delta bunch for short range wake field simulation since a 0.6 mm bunch contains frequency much higher than the 1 cm bunch. A short range wake field simulation was done using CST Particle Studio™ with 0.6 mm rms Gaussian bunch at the speed of light, and this result was compared with the result for 1 cm rms Gaussian bunch in Figure 1, from where one notice that the wake potential for the 0.6 mm bunch is ~10 times higher than that of the 1 cm bunch. The wake potential of the 0.6 mm bunch, as well as the charge distribution, was then “shift and stack” every 0.75 mm, the normalized results are shown in Figure 2. The wake loss factor (WLF) is the integration of the product of wake potential and normalized bunch charge, and the energy spread factor (ESF) is the rms deviation from the average energy loss. It is calculated by summing the weighted squares of the differences and taking the square root of the sum. These two factors were then divided by β2 for 1.6 MV beam energy. The wake loss factor is at 0.86 V/pC and energy spread factor is at 0.54 V/pC rms. With 100 pC electron bunch, the energy spread inter-bunch is 54 V rms.},

doi = {10.2172/1436272},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Mon Jan 08 00:00:00 EST 2018},

month = {Mon Jan 08 00:00:00 EST 2018}

}