LCLS-IISC Parameters

LCLS-IISC ParametersTor Raubenheimer

LCLS-II Overview 2

Operating modes

1.0 - 18 keV (120 Hz)1.0 - 5 keV (100 kHz)

0.2-1.2 keV (100kHz)4 GeV SC Linac

•Two sources: high rate SCRF linac and 120 Hz NCu LCLS-I linac

•North and south undulators always operate simultaneously in any modeUndulator

SC Linac (up to 100kHz) Cu Linac (up to 120Hz)

North 0.25-1.2 keV

South 1.0-5.0 keV up to 18 keVhigher peak power pulses

Cu Linac

• Concurrent operation of 1-5 keV and 5-18 keV is not possible

3

Preliminary Operating Parameters

LCLS-II Overview

Preliminary LCLS-II Summary Parameters v0.7 8/30/13

North Side Source South Side Source

Running mode SC Linac SC Linac Cu Linac

Repetition rate up to 1 MHz* up to 1 MHz* 120 Hz

Electron Energy 4 GeV 4 GeV 14 GeV

Photon energy 0.25-1.2 keV 1-5 keV 1-20 keV

Max Photon pulse energy (mJ) (full charge, long pulse)

up to 2 mJ* up to 2 mJ* up to10 mJ

Peak Spectral Brightness (10 fs pulse) (low charge, 10pC)

3.9x1030 ** 12x1030 ** 247x1030 **

Peak Spectral Brightness(100fs pulse) (full charge, 100pC)

3.0x1030 ** 6.9x1030 ** 121x1030 **

* Limited by beam power on optics **N_photons/(s*mm^2*mrad^2*0.1% bandwidth)

4Insert Presentation Title in Slide Master

High Level Schedule


More Immediate Schedule

1. Mid-October Workshop to review design, cost and

schedule with collaborators

2. Mid-December Director’s Review for CD1 Review

3. Mid-January CD1 Lehman Review

Also may need to have a FAC review prior to CD1 review

Mid-November ??


Assumed Beam Parameters

The assumed emittance of 0.43 at 100 pC is roughly 25% larger than

the LCLS-II baseline. It is more conservative than the NLS or the

scaled NGLS values (the latter are consistent with the LCLS-II baseline)

however a gun has not yet been demonstrated that achieves the

desired emittances. Reduced emittances will decrease gain lengths.

Peak current is consistent with higher energy beams and BC’s

NLS NGLS LCLS-IISC

Beam energy [GeV] 2.25 2.4 4

Bunch charge [pC] 200 300 100

Emittance [mm-mrad] 0.3 0.6 0.43

Energy spread [keV] 150 150 keV 300 keV

Peak current [kA] 0.97 0.5 1

Useful bunch fraction [%] 40 50 50


Example of Injector: APEX


SCRF Linac

Roughly 400 meters long including laser heater at ~100

MeV, BC1 at ~300 MeV and BC2 at 1000-2000 GeV. Long

bypass line starting at Sector 9 BSY. LTU similar to

LCLS-IISA discussed last month.

Based on 1.3 GHz TESLA

9-cell cavity with minor

mods for cw operation

9

1.3 GHz 8-cavity cryomodule (CM)

• It is proposed to use an existing cryomodule design for the 4-GeV

LCLS-II SRF linac.

• CM is roughly 13 meters for 8 cavities plus a quadrupole package

• The best-fit is the EU-XFEL cryomodule

• Modifications are required for LCLS-II• (The CEBAF 12 GeV upgrade module must also be considered)• (The ILC CM is similar but has several important differences and is

not as well suited for CW application)

• 100 cryomodules of this design will be built and tested by the

XFEL by 2016 Global industrial support for this task

• One XFEL ~prototype CM was assembled and tested at Fermilab• (Fermilab assembled an ILC cryomodule and has parts for another)\

10

Linac

v0.9 2013-08-30

Linac parameters

Energy 4 GeV

Cavity Gradient 16 MV/m

Cavity Q_0 2E+10

Operational temperature 1.8 deg_K

rate 1E+06 Hz

Average current 0.3 mA

Beam power 1.2 MW

Cryogenics power 3.0 MW

Total SC RF AC Power 3.4 MW

SC Layout

1.3 GHz Cryomodules 34 (+1 spare) count

1.3 GHz Voltage 4.2 GV

1.3 GHz Cavities 264 count

1.3 GHz Rf power/cavity 7 kW

1.3 GHz Cavities/klystron 32 count

1.3 GHz SSA 24 count

1.3 GHz Cryomodules/klystron 4 count

1.3 GHz Dist. Between klystrons 57 m

1.3 GHz Klystron avg. power 3.0E+05 W

1.3 GHz Klystron (10% margin) 8

1.3 GHz Mod V 50 kV

1.3 GHz Mod A 10 A

1.3 GHz Sector-pair RF AC power 1.32E+06 W

1.3 GHz Cryomodule spacing 13 m

3.9 GHz cryomodules 3 count

3.9 GHz Voltage 60 MV

3.9 GHz Cavities 12 count

3.9 GHz Cavities/klystron 4 count

L0 length 8 m

L1 RF length 16 m

LC length (3.9 GHz) 4 m

L2 RF length 96 m

L3 RF length 144 mTotal Linac length; not incl BC1 BC2 405 m

No warm breaks except BC: 1 cryo circuit per 3 kW load

11

Linac View

SLAC Linac

(11 wide x 10 feet high)

(3.35 x 3.05 m)

x

12

First 800 m of SLAC linac (1964):

Cryoplant placement and construction

350 m

Injector Length


Assumed FEL Configuration

• High rep rate beam could be directed to either of two undulators

HXR or SXR bunch-by-bunch

• 120 Hz beam could be directed to the HXR at separate times

• The SC linac would be located in Sectors 0-10 and would be

transported to BSY in the 2km long Bypass Line. It would use a

dual stage bunch compressor.

• A dechirper might be used to further cancel energy spread for

greater flexibility in beam parameters

• The high rep rate beam energy would be 4 GeV and the HXR

would fill the LCLS hall with ~144 m while the SXR would be <75

m so that it could be fit into ESA

• Both undulators would need to support self-seeding as well as

other seeding upgrades


Undulator Requirements

Requirements:

1. SXR self-seeding operation between 0.2 and 1.3 keV

in ESA tunnel (<75 meters) with 2.5 to 4 GeV beam

2. HXR self-seeding operation between 1.3 and 4 keV in

LCLS tunnel (~144 meters) with 4 GeV beam

3. HXR SASE operation up to 5 keV with 4 GeV beam

4. Primary operation of SXR and TXR at constant beam

energy large K variation

5. HXR operation comparable to present LCLS with 2 to

15 GeV beam


Undulator Parameters

1. To cover the range of 0.2 to 1.3 keV using SASE in less

than 50 meters (to allow for seeding) lw ~ 40 mm

• A conventional hybrid undulator with 40 mm and a 7.2 mm

minimum gap would have Kmax ~ 6.0 which easily covers

the desired wavelength range at 4 GeV

2. To achieve 5 keV using SASE with less than 144 m

at 4 GeV TXR lw <= 26 mm

• A conventional hybrid undulator with 26 mm and a 7.2 mm

minimum gap would have Kmax ~ 2.4 which covers desired

wavelength range at 4 GeV• Provides reasonable performance with LCLS beam

Baseline Tuning Range for 4 GeV

HXR: lu = 26 mm, L = 144 m

SXR: lu = 41 mm, L = 75 m

SASE

Self-Seeding

Self-Seeding

Kmax = 6.0

Kmin = 1.6

Kmax = 2.44

Kmin = 0.91

Kmin = 0.55

Kmin is chosen to saturate within given length for SASE or Self-seeding

Kmax is set to the maximum value for a 7.2 mm gap variable gap undulator

Ebeam [GeV]

Eph

oton

[keV

]


X-ray pulse energy at High Rate

More than enough FEL power although results assume full beam and are ~2x optimistic


Comparison of HXR with LCLS performance at 120 Hz (1)

26 mm HXR covers 2 keV at ~4 GeV to 30+ keV at 14 GeV – beam energy might be reduced further if desired


Comparison of HXR with LCLS performance at 120 Hz (2)

26 mm HXR provides lower pulse energy than 30 mm LCLS but much shorter l


Options for HXR: SCU, IV, or 30 mm period (1)

To recover the LCLS performance, we need to increase K. Can (1) increase the

period, (2) adopt an in-vacuum design, or (3) consider a planar or helical SCU.

Example of a helical SCU below

however have not included poorer SCU fill factor results are optimistic


Options for HXR: SCU, IV, or 30 mm period (2)

Example of a 30 mm period hybrid undulator below. Nearly recovers LCLS

performance (reduction due to slightly larger gap with VG undulator) however the

maximum photon energy at high rate, i.e., 4 GeV is now 4.3 keV not 5 keV as

with 26 mm period


SCU options

An SCU has a number of benefits:

1. Would attain comparable performance as LCLS even

while achieving 5 keV at 4 GeV at high rate by operating

with high K

2. Would allow shorter SXR period to reduce SXR beam

energy and gain length to ensure space in ESA while still

covering full wavelength range at constant energy.

J. Wu (SLAC), [email protected], 08/05/2013 23

GENESIS SIMULATION ELECTRON PARAMETERS

Centroid energy 4 GeV; 100 pC compressed to 1 kA; normalized emittance: 0.45 mrad; slice energy spread: sE = 300 keV except for LCLS case with 15 GeV

6 cases – details in following pagesCase 1: HXR Kmin = 0.91; lw = 26 mm; Lw = 144 m (study SS 4keV)

Case 2: SXR Kmin = 1.6; lw = 41 mm; Lw = 75 m (study 1.6 keV)

Case 3: SXR Kmax = 6.0; lw = 41 mm; Lw = 75 m (study 200 eV)

Case 4: SXR K = 1.9; lw = 41 mm; Lw = 75 m (study 1.3 keV)

Case 5: SXR K = 2.0; lw = 30 mm; Lw = 75 m (short gain len.)

Case 6: HXR in LCLS TW parameters but K too high for hybrid undulator

Bad

Barely

Good

Good

Good

OK

24

Potential Areas of Collaboration with Partner Labs

SLAC LBNL FNAL JLAB ANL Cornell Wisconsin

Injector X X X

Undulator X X

SC linac prototype X X X

SC Linac X X

SC cryo line X X

Cryo plant X X

LLRF X X X X

RF systems X

Beam Physics X X

Instruments/Detectors

X X

PM/Integration X

Installation X X X

Commissioning X

LCLS-II Overview


Points of Contact


CDR Writing

• Must keep the document concise – it is a conceptual design

1. Executive Summary (Galayda)

2. Scientific Objectives (TBD)

3. Machine Performance and Parameters (Raubenheimer)

4. Project Overview (Galayda)

5. Electron Injector (Schmerge)

6. Superconducting Linac Technologies (Ross,Corlett)

7. Electron Bunch Compression and Transport (Raubenheimer, Emma)

8. FEL Systems (Nuhn)

9. Electron Beam Diagnostics (Frisch, Smith)

10. Start-to-End Tracking Simulations (Emma)

11. Photon Transport and Diagnostics (Rowen)

12. Experimental End-Stations (Schlotter)

13. Timing and Synchronization (Frisch)

14. Controls and Machine Protection (Shoaee, Welch)

15. Conventional Facilities (Law)

16. Environment, Safety and Health (Healy)

17. Radiological Issues (Rokni)

18. Future Upgrade Options (Galayda)

Documents

LCLS-IISC Parameters