1

Energy recovery linacs

Sverker WerinMAX-lab

8 July 2003

2

Energy recovery linacs

Sverker WerinMAX-lab

8 July 2003

• Source development

• What is an ERL?

• Quality of radiation

• Special ERL topics

• Instabilities and limitations

• Challenges and development

• ERLs yesterday, today and tomorrow

# 3

S. Werin

Path of development

Light sources

• 1st generation parasitic SR on high energy physics storage rings

• 2nd generation dedicated bending magnet sources

• 3rd generation dedicated undulator sources

• 4th generation…. Need in the future

• Coherence

• Power

• Fs pulses

• Diffraction limited radiation

• Brilliance – average/peak

Have today

• Repetition rate

• Stability

• Tunability

• Polarisation

• Brilliance – average/peak

FEL

ERL

?

3.5th gen

# 4

S. Werin

Gives us

• Coherence

• Power

• Pulse slicing fs pulses

• Some diffraction limited radiation

• Brilliance – average/peak

3.5 generation storage ring

http://www.diamond.ac.ukhttp://www.soleil.u-psud.fr

# 5

S. Werin

Gives us

• Coherence

• Power

• Fs pulses

• Diffraction limited radiation

• Brilliance – average/peak

• Low repetition rate

Free electron laser

http://www.bessy.de/publications/01.felscientific/sc.html

# 6

S. Werin

Energy Recovery Linac

Gives us

• Coherence

• Power

• Fs pulses

• +Diffraction limited radiation

• Brilliance – average/peak

• Medium repetition rate

Cornell ERL D. Bilderback, SRN 2/27/01.

Articles on "ERL" or "Energy Recovery Linac"

0

5

10

15

20

25

30

35

40

EP

AC

96

PA

C 9

7

EP

AC

98

PA

C 9

9

EP

AC

00

PA

C 0

1

EP

AC

02

PA

C 0

3

M. Tigner, Nuovo Cimento 37 (1965)1228.

# 7

S. Werin

What is an ERL?

Linac

injection

# 8

S. Werin

What is an ERL? Step 2

Opposite phase Deceleration

Energy given back to linac structure and stored there

• Emittance defined by source/gun ( not ring equilibrium)

<=0.1 nmRad

• Brilliance >= storage rings

• Pulse length small (not ring equilibrium)

< 100 fs

• SC linac – save RF power, independent of current

• CW operation (gun limit)

KHz-MHz

• Low dump energy, less radioactivity

<10 MeV

# 9

S. Werin

Linac power

swall Z

LEP

ˆ

wallPQ

W

Q

t

eEE

10

Loading of a cavity

0

0,2

0,4

0,6

0,8

1

1,2

0 0,5 1 1,5 2 2,5 3 3,5 4

Time

Fie

ld

Loading of a cavity

0

0,2

0,4

0,6

0,8

1

1,2

0 0,5 1 1,5 2 2,5 3 3,5 4

Time

Fie

ld

Loading of a cavity

0

0,2

0,4

0,6

0,8

1

1,2

0 0,5 1 1,5 2 2,5 3 3,5 4

Time

Fie

ld

Shunt impedance

Q-value

QNC ~ 1*104

QSC-TESLA ~ 3*109

# 10

S. Werin

Brilliance

2'

2''

22

''24

rxx

rxx

yyxx

FluxBrilliance

Peak brilliance

During the peak of a bunch

Average brilliance

Forever or during a macro pulse from the accelerator

ABWs

photonsFlux

%1.0

What counts

To compare

# 11

S. Werin

Brilliance

2'

2''

22

''24

rxx

rxx

yyxx

FluxBrilliance

1E+15

1E+17

1E+19

1E+21

1E+23

1E+25

1E+27

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

Energy (eV)

Ave

rag

e B

rilli

ance

(p

h/s

*mR

ad^2

*mm

^2*0

.1%

BW

)

Peak brilliance Average brilliance

TESLA

TTF

LCLS

Diamond

SPring8ESRF

APS

BESSY II

Cornell ERL

USRLS

1E+19

1E+21

1E+23

1E+25

1E+27

1E+29

1E+31

1E+33

1E+35

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

Energy (eV)

Pea

k B

rilli

ance

(p

h/s

*mR

ad^2

*mm

^2*0

.1%

BW

)

TESLA

TTFLCLS

SPring8

APSBESSY II

ESRFDiamond

Cornell ERL

USRLS

# 12

S. Werin

Diffraction limit

Diffraction emittance -

0,01

0,1

1

10

100

0,0E+00 5,0E+02 1,0E+03 1,5E+03 2,0E+03

Photon energy (eV)

Em

itta

nc

e (

nm

Ra

d)

2'

2''

22

''24

rxx

rxx

yyxx

FluxBrilliance

2

rr

# 13

S. Werin

Emittance comparison

Vertical emittance

Ring

3

2

periodicity

Emittance

ERL/Linac

1Emittance

Horisontal emittance

Ringvert ≈ 0.05 hor

ERLvert= hor

# 14

S. Werin

0

1

2

3

4

5

6

7

0 2 4 6 8 10

Energy (GeV)

Em

itta

nc

e -

nm

Ra

d

Ring

ERL

ESRF

APS

SPring8

ERL-1

M4-X

M4-SoftX

ALS

Diamond

BESSY II

Soleil

USRLS

ERL/Linac1 mm mRad

Ring

3

2

M

1

Emittance comparison

Horisontal emittance

Vertical emittance

# 15

S. Werin

Pulse length

Storage ring 10 ps Lifetime sacrifice

+ bunch slicing 50 fs Low flux, simple

Linac (FEL, ERL) ~ 20 fs Photo cathode laser, space charge, CSR (coherent synch.rad.), slippage

# 16

S. Werin

Quick duty

30 6015 45

Discuss with your neighbour

A 20 fs electron bunch passes a 100 period long undulator producing radiation at a wavelength of 60 nm.

How long is the radiation pulse?

The radiation from one e- consists of a wave train with 100 periods at 60 nm 100*60 nm = 6*10-6 m

The length in time is 6*10-6/c = 6*10-6/3*108 = 20 fs

Add the pulse length and the total length will be 20 + 20 = 40 fs

Please talk!

# 17

S. Werin

A 100 mA 5 GeV electron beam carries 500 MW

power.

Stornorrfors powerstation

591 MW @ 1000 m3/s

Energy savings …?

Save energy!

# 18

S. Werin

Energy savings go superconducting

LBL LUX proposal

600 MeV linac – 4 recirculations

10 KHz

NC SC

RF-power peak 240 MW 0.288 MW

RF-power average 6 MW 0.288 MW

Cooling power 0 ~3.5 MW

6 MW 3.8 MW

# 19

S. Werin

Energy savings (nasty version)

Cornell ERL2 - 5 GeV 100 mA

v.

ESRF - 5 GeV 200 mA

Cornell ESRF

RF-power peak 1.1 MW 2.6 MW

RF-power average 1.1 MW 2.6 MW

Cooling power 16.4 MW 0

17.5 MW 2.6 MW

# 20

S. Werin

Radiation savings …?

100 mA5 GeV

RecoveryDump @ 10 MeV

1 MW

NO recoveryDump @ 5 GeV

500 MW

ESRF200 mA, 5 GeV

24 hours, c 850 m31 mW

Dump beam powers

Much less neutron

production

ERL

linac

# 21

S. Werin

Limitations

Increasecurrent

Shorterbunches

Wakefields

HOMs

Heat upof SC cavities

CSR

Energy spread

Emittanceincrease

Coolingpower

increase

Space chargeeffects

# 22

S. Werin

Beam Break Up (BBU)

Displacement of the bunch due to transverse wakefields induced by a previous bunch beeing off center.

Damp modes

Good alignment

# 23

S. Werin

Coherent Synchrotron Radiation

A sufficiently short bunch will radiate coherently.

The radiation from the tail can irradiate the head of the bunch.

Energy spread

Emittance growth if dispersion

Cure:

Longer bunches, less current

Shielding, larger radius

# 24

S. Werin

Challenges

Guns ► CW

Optics in arcs ► Multi energy, CSR

Control of RF ► The beam ”runs” the RF

Beam loss ► Messes up RF

Instabilities (BBU…) ► Limits current

HOM cooling ► More power to SC cooling

# 25

S. Werin

1960

1970

1980

1990

2000

Around the world

MUSL Univ of Illinois, 1977

SCA, Stanford, 1986

S-DALINAC, 1990CEBAF, 1995IR FEL Jlab, 1999JAERI, 2002

LUX (LBL)

CornellPERL (NSLS)

4 GLS (Daresbury) ERLSYN (Erlangen) KEK…

M. Tigner, Nuovo Cimento 37 (1965)1228.

# 26

S. Werin

MUSL-2 – Univ. Of Illinois

# 27

S. Werin

Stanford SCA

First energy recovery

T.I. Smith, et al, NIM A 259 (1987) 1-7

50 MeV

# 28

S. Werin

JAERI – ERL + FEL

17 MeV

5 mA

In operation

N. Nishimori et.al., EPAC 2002, Paris

# 29

S. Werin

S-DALINAC - Darmstadt

http://linac.ikp.physik.tu-darmstadt.de/linac/introduction.html

130 MeV

# 30

S. Werin

Jlab FEL

http://www.jlab.org/FEL/feldescrip.html

IR Demo FEL

In operation since 1999

40 MeV

5 mA

FEL upgrade

2003 -

160 MeV

10 mA

Jefferson LabNewport News, VA

# 31

S. Werin

MARS Multipass Accelerator Recuperator Source

Novosibirsk

G. Kulipanov et.al. SRI 2001, ERL workshop

undulator

undulator

undulator

undulator

Linac 700 MeV

Gun Injector

Linac

Dump

6 GeV

# 32

S. Werin

CEBAF

CEBAF 6 GeV (12 GeV upgrade)

Jefferson LabNewport News, VA

http://www1.jlab.org/ul/jpix/high/upgrade_187.jpg

# 33

S. Werin

LUX - LBL

http://jncorlett.lbl.gov/FsX-raySource/

3 GeV proposal

Multi-user facility proposalRepetition rate 10 kHzPulse length < 100 fsCurrent 10 µA

# 34

S. Werin

Cornell-Jefferson ERL

Proposal

Cornell, Ithaca NY

Energy 100 MeV phase I 5 GeV phase II

Current 10/100 mA

D. Bilderback, SRN 2/27/01.

Cornell ERL

# 35

S. Werin

PERL

J. Murphy, SRI 2001, ERL workshop

NSLS, Long Island

# 36

S. Werin

4 GLS

http://www.4gls.ac.uk/

Daresbury, UK

# 37

S. Werin

ERLSYN

http://www.erlsyn.uni-erlangen.de/

3.5 GeV

Erlangen, Germany

# 38

S. Werin

KEK ERL

http://conference.kek.jp/JASS02/23_harada.pdf

Photon Factory - KEK

Energy 2.5 ~ 5.0 GeV

Beam Current ~100 mA

Horizontal Emittance ~0.01 nmRad

Bunch Length 1 ps ~ 100 fs

# 39

S. Werin

Summary ERLs will give us

Fs pulses (some tricks needed)

CW (almost) KHz-MHz repetition rate

Brilliance ≥ new rings above 5 GeV

Diffraction limited < 2-5 KeV = ”Ultimate source”

Reduced radiation from dump (v. linacs)

Proof of principle done

Many new proposals, especially in the US

Compact CW driver for FEL

But

• Small energy savings

• Instabilities limits current

• HOMs limits short bunches

Diffraction limit

Coherence Fs pulses

Multi user

Brilliance,average

Brilliance, peak

Rep. rate

Storage ring -hor, +vert - - + 0 - +

FEL 0 + + 0 0 + -

ERL 0 - + + 0 - 0

40

END