Hard X-ray S-2-E FEL simulation for LCLS-II CDR
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Transcript of Hard X-ray S-2-E FEL simulation for LCLS-II CDR
![Page 1: Hard X-ray S-2-E FEL simulation for LCLS-II CDR](https://reader035.fdocuments.us/reader035/viewer/2022081508/5681341c550346895d9b089b/html5/thumbnails/1.jpg)
Hard X-ray S-2-E FEL simulation for LCLS-II CDR
J. WuIn discussion with Y. Ding, P. Emma, Z. Huang,
H.-D. Nuhn 02/01/2011
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LCLS-II: Ranges for Individual Bunch Operation
(From H-D Nuhn, 10/13/2010)
Simulation example
![Page 3: Hard X-ray S-2-E FEL simulation for LCLS-II CDR](https://reader035.fdocuments.us/reader035/viewer/2022081508/5681341c550346895d9b089b/html5/thumbnails/3.jpg)
Setup
• FEL at 13.5 keV,• Electron Centroid Energy 13.5 GeV; peak
current 3 kA– S2E file down to undulator entrance taken from P.
Emma
• Undulator lw = 3.2 cm; each section is about 4.4 m long with 3.4 m magnetic length; beta-function ~ 20 m
![Page 4: Hard X-ray S-2-E FEL simulation for LCLS-II CDR](https://reader035.fdocuments.us/reader035/viewer/2022081508/5681341c550346895d9b089b/html5/thumbnails/4.jpg)
Electron bunch @ undulator entrance
• Current profile (head at right)
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Without wakefield
• The S2E input electron distribution function is injected into an ideal undulator without any wakefield effect
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FEL power
• Along the undulator: Saturation around 60 m
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FEL profile and spectrum
• Along the undulator at 100 m
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Energy loss• Along the undulator: entrance (black), 60 m
(red), 120 m (blue), and 150 m (green) – electron bunch head at right
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Energy spread• Along the undulator: entrance (black), 60 m
(red), 120 m (blue), and 150 m (green) – electron bunch head at right
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Setup
• FEL at 13.5 keV,• Electron Centroid Energy 13.5 GeV; peak
current 3 kA– S2E file down to undulator entrance taken from P.
Emma (No LSC included)
• Undulator lw = 3.2 cm; each section is about 4.4 m long with 3.4 m magnetic length; beta-function ~ 35 m
![Page 11: Hard X-ray S-2-E FEL simulation for LCLS-II CDR](https://reader035.fdocuments.us/reader035/viewer/2022081508/5681341c550346895d9b089b/html5/thumbnails/11.jpg)
Electron bunch @ undulator entrance
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With resistive-wall wakefield• We assume 5 mm diameter round aluminum
pipe; no surface roughness wake, no geometric wake; head at left
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FEL power• Along the undulator: Saturation around 80 m;
with wakefield compensation of 150 keV/m which in reality is a tapering in the undulator
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FEL power• Along the undulator: 80 m – electron bunch
head at left
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FEL power• Along the undulator: 100 m – electron bunch
head at left
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FEL power• Along the undulator: 120 m – electron bunch
head at left
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FEL power• Along the undulator: 140 m – electron bunch
head at left
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FEL spectrum• At the undulator end: 140 m– electron bunch
head at left
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FEL spectrum• The wide spectrum is partially due to the
wakefield induced energy chirp along the electron bunch, head at left