# Presentation: 667803

## LCLS Project Overview

**What is the LCLS ?**
**Transition from 3****rd**** generation light sources to x-ray free-electron lasers**
**The SASE principle and linac-driven free-electron lasers**
**Performance**
**Accomplishments**
**R&D and construction plan**

## Single pass Free-Electron Lasers
Uses SLAC Linac
1.5 - 15 Å (0.5-5 Å in 3rd harmonic)
Peak brightness 10 orders of magnitude above Advanced Photon Source (APS)
Time averaged brightness 2-4 orders of magnitude above APS
Sub-picosecond pulses
Fully transversely coherent radiation
Design and R&D studies, a ANL-BNL-LANL-LLNL-SLAC-UCLA collaboration

The X-ray FEL is a powerful tool to explore matter and fundamental physics.

**Uses SLAC Linac**
**1.5 - 15 Å (0.5-5 Å in 3rd harmonic)**
**Peak brightness 10 orders of magnitude above Advanced Photon Source (APS)**
**Time averaged brightness 2-4 orders of magnitude above APS**
**Sub-picosecond pulses**
**Fully transversely coherent radiation**
**Design and R&D studies, a ANL-BNL-LANL-LLNL-SLAC-UCLA collaboration**
*The X-ray FEL is a powerful tool to explore matter and fundamental physics.*

- What is the LCLS ?

## The transition from 3rd generation light sources to x-ray free-electron lasers

**FELs**

## The SASE principle and linac-driven free-electron lasers

**Main components of a SASE FEL**
- A bright electron source (photo-injector)
- A bunch compression system
- A linear accelerator
- An undulator
- The photon beamlines
- The experimental areas

## LCLS layout

## SASE FELs

- and verified by simulations and experiments
*FEL radiation starts from noise in spontaneous radiation *
*Transverse radiation electric field modulates the energy and bunches the electrons within an optical wavelength*
* *
*Exponential build-up of radiation along undulator length*

- Undulator Regime

- Exponential Gain Regime

- Saturation

**0.2 fs**

**0.9 fs**

- 1 % of X-Ray Pulse

- Electron BunchMicro-Bunching

## 
Wavelength 		1.5 Å 
	(range 1.5-15 Å, 1st harm)

Electron energy  	14.35 GeV (range 14.35-4.54)

Bunch length	  	230 fsec (full)

1012 coherent photons/pulse

Undulator length	120 m

Undulator gap		6 mm

- Wavelength 		1.5 Å
- 	(range 1.5-15 Å, 1st harm)
- Electron energy  	14.35 GeV (range 14.35-4.54)
- Bunch length	  	230 fsec (full)
- 1012 coherent photons/pulse
- Undulator length	120 m
- Undulator gap		6 mm

**Saturation peak power**
**	****9 GW**
**Peak brightness**
**	****1.2 10****33**
**Average brightness**
**	****4.2 10****22**

- Main parameters

## Light source performance chart

***Peak and time***
***averaged ***
***brightness***
***of the LCLS and other facilities,***
***operating or ***
***planned***

- Average

- Peak

## Other FEL based light sources are being tested, built or planned

**The TESLA Test Facility (TTF) at DESY**
- Lasing with gain ~3000 observed at 80-180 nm
**X-ray FEL TESLA at DESY (associated with the linear collider project**)
- CDR being written
**Source Development Laboratory (SDL) at BNL-NSLS**
- Electron beam testing
**Harmonic Generation (HGHG) experiment successful at BNL-ATF**
**VISA experiment at BNL-ATF**
- Study the FEL radiation with beam characteristics and tolerances close to those of the LCLS
**FELs under study in Japan, Italy, England and Germany (BESSY II)**
***LEUTL at ANL-APS***
***First observation of saturation***

## FEL experiment

- A crucial milestone in FEL physics was reached when the LEUTL experiment measured large amplification and evidence of saturation last summer at 530 and 385 nm

## 6D particle tracking through LCLS accelerator

- 150 MeV

- 250 MeV

- 250 MeV

- 4.54 GeV

- 14.3 GeV

- Energy deviation along electron bunch

- Transverse cross section of electron beam

## How to achieve a short bunch

- The simulation tool was used to optimize the electron beam in 6-dimensional phase space
- Preservation of transverse electron brightness leads to shorter undulator and more relaxed tolerances
- Mechanism for achieving short electron bunches (230 fs) confirmed by the simulations
- Even shorter bunches can compromise transverse electron brightness
***230 fs bunch length is the result of optimization in all 6 dimensions***

## X-ray optics transport simulations

**GINGER output:**

**Tables of electric field values**
**at undulator exit**
**at different times**

**viewer**

**Viewer**

**Transformation to**
** ****Frequency Domain**

**Propagation**
**to arbitrary**
**z**

***R, ******m******m***

## LCLS Undulator Hall and Experimental Area Layout

- FFTB hall for undulator and diagnostics

***LCLS Undulator Hall and Experimental Area Layout***

- Hall A:
- Atomic Physics
- Warm Dense Matter
- X-Ray Physics

- Hall B:
- Nanoscale Dynamics
- Femtochemistry
- Biological Imaging

## Conceptual Design Report

- Conceptual Design Report is on schedule
- First draft contributions are being reviewed
- Goal is to have it ready, in draft form, by early summer 2001

## Summary

- Substantial progress made in most areas
- Experimental confirmation of the photo-injector brightness is the most important short term goal
- Program is receiving strong support from SLAC
- Integration photo-injector/FEL physics/x-ray optics to continue
*Realistic x-ray FEL characteristics, tolerances, match to the experiments*
- X-ray optics to address detailed requirements of the “first experiments”
- Focus on CDR for the next 6-8 months
- Preparation for Lehman Review