Charge and Bunch Length Scope

-2 -1 0 1 2

13.995

14

14.005

Compression Scenarios for the European XFEL

Charge and Bunch Length Scope

Igor Zagorodnov

1st Meeting of the European XFEL Accelerator Consortium

DESY, MPY14. April 2012

[GeV]E

[μm]s

Igor Zagorodnov| 1st Meeting of EXFEL Accelerator Consortium | 17. April 2012 | Seite 2

Inhalt

Analytical and Numerical Approaches Compression Scenarios for Different Charges Strong Compression Summary


Analytical and Numerical ApproachesLayout

1 130MeVE 1,1M

Gun

1,3M

2M 3M 4M

LH

DL 1BC 2BC 3BC2 700MeVE 3 2400MeVE 4 14 /17.5GeVE


Analytical and Numerical Approaches

1

56,1

1

130MeV?

?

ER

C

2

56,2

2

700MeV?

?

ER

C

3

56,3

2400MeV?

ER

Working points (11 macro-parameters)

What is the optimal choice?

1,1M

Gun

1,3M

2M 3M 4M

LH

DL 1BC 2BC 3BC

, ,C C C

Zagorodnov I., Dohlus M., A Semi-Analytical Modelling of Multistage Bunch Compression with Collective Effects, Phys. Rev. ST Accel. Beams, 2011.


-100 -50 0 50 1000

1

2

3

4

-5 0 50

0.01

0.02

0.03

0.04

[mm]s

1( )C s

3 [μm]s

[kA]I

(0) 0C

Analytical and Numerical ApproachesChoosing of machine parameters

very strong compression at the bunch head (spike)

(0) 0C



ACC39 ACC4/5/6/7ACC39 ACC4/5/6/7

~ 1.5 kA

~2.5 kA

slice emittance > 2mm

slice emittance ~ 0.3 - 1mm

Q=1 nC

Q=0.5 nC

Rollover Compression vs. Linearized (FLASH)


Analytical and Numerical Approaches[MeV]E

[μm]s

[kA]I[μm]s

[μm]s[μm]s

[MeV]E

[kA]I

0C 0C

Q=1 nC


Analytical and Numerical ApproachesAnalytical solution without self-fields

10 0 0( )x A f

Solution with self-fields

0( ) A x f

10 ( )n nx A g

nonlinear operator (tracking with self-fields)

1 1n n n g g f

10 0 0( ) ( ) x A A x f A x

10 0 1 0 1( ) ( )n n n

x A A x f A x

numerical tracking

analytical correction of RF parameters

1 1( )n n f A x

1 0 1n n f f fresidual inmacroscopic parameters

1,1

1,1

1,3

1,3

2

2

3

3

V

V

V

V

x

1

2

3

10

2

EEECCCCC

f

Zagorodnov I., Dohlus M., A Semi-Analytical Modelling of Multistage Bunch Compression with Collective Effects, Phys. Rev. ST Accel. Beams, 2011.



1 130MeVE

Beam dynamics simulation

1,1M

Gun

1,3M

2M 3M 4M

LH

DL 1BC 2BC 3BC2 700 MeVE 3 2400 MeVE 4 14GeVE

ASTRA ( tracking with 3D space charge, DESY, K. Flötmann)

W1 -TESLA cryomodule wake (TESLA Report 2003-19, DESY, 2003)W3 - ACC39 wake (TESLA Report 2004-01, DESY, 2004)TM - transverse matching to the design optics

W3

W1

TM4W1

TM64W1

12W1

TM

Full 3D simulation method (200 CPU, ~10 hours)

CSRtrack (tracking through dipoles, DESY, M. Dohlus, T. Limberg)

1.6 kmz


Compression for Different Charges

-40 -20 0 20 40 600

1

2

3

4

5

Q=1 nCE

[kA]I

Phase space

[MeV]E

0.9 [μm]projx

3.5 [μm]projy

Current, emittance, energy spread

[μm]x[μm]y

[μm]s [μm]s

178fs

bunch head

-40 -20 0 20 40 60

13.998

14

14.002

14.004

14.006

14.008



-20 -10 0 10 200

0.2

0.4

0.6

0.8

1E Phase space

[MeV]E

0.45 [μm]projx

1.5[μm]projy


[μm]x

[μm]y

[μm]s [μm]s

39fs

bunch head

5kAI

-10 0 10 20

13.995

14

14.005

14.01

Q=250 pC



-2 -1 0 1 20

0.2

0.4

0.6

0.8

1

[MeV]E

0.14 [μm]projx

0.26 [μm]projy


[μm]x[μm]y

[μm]s

2fs

5kAI

E

[μm]s

-2 -1 0 1 2

13.995

14

14.005

Phase spaceQ=20 pC



Parameter UnitBunch charge nC 1 0.5 0.25 0.1 0.02

Peak current (gun) A 43 24 13.5 5.7 1.2Bunch length (gun, FWHM) ps 25 22 20 17 17

Slice emittance (gun) mm 0.8 0.5 0.3 0.21 0.09Projected emittance (gun) mm 1 0.7 0.6 0.3 0.1

Compression 114 233 363 877 3833

Peak current kA 4.9 5.6 4.9 5 4.6Bunch length (FWHM) fs 178 72 39 12 2.2

Slice emittance mm 1 0.7 0.5 0.3 0.17Projected emittance mm 3.5 2.2 1.5 0.84 0.26Slice energy spread (laser heater off)

MeV 0.45 0.44 0.6 0.6 0.8

Beam parameters from S2E simulations



-30 -20 -10 0 10 200

5

10

15

20

25

30

35

0 50 100 1500

0.5

1

1.5

2

Radiation Q=1nC. SASE[GW]P

[μm]s

[mJ]W

[m]z

Genesis

ALICE

Genesis

ALICE

Zagorodnov I., Dohlus M., Numerical FEL studies with a new code ALICE, in Proceedings of FEL09, Liverpool, 2009.



0 50 100 1500

5

10

15

20

25

30

0 50 100 150

10-4

10-2

100

Radiation energy statistics (1-25-120 runs) mJE

[m]z

250 pC

1 nC

Mean energy

20 pC

fsz

Radiation pulse width (RMS)

Charge, nC 1 0.25 0.02Mean radiation energy, mJ 1-4 1-2 0.1-0.4Pulse radiation width (FWHM), fs 25-50 10-20 1-2

250 pC

1 nC

20 pC

[m]z



Bunch charge, nC 1 0.25 0.02Wavelength, nm 0.1

Beam energy, GeV 14Peak current, kA ~ 5

Slice emmitance,mm-mrad 1 0.5 0.2Saturation length, m 85 60 45

Energy in the rad. pulse, mJ 1-4 1-2 0.1-0.4

Radiation pulse duration FWHM, fs 25-50 10-20 1-2Averaged peak power, GW 10-50 10-100 50-150

Spectrum width, % 0.15-0.3 0.18-0.5

Radiation Properties from S2E


Strong Compression

-40 -20 0 20 40 600

1

2

34

5

67

8

910

Q=1 nC, I=10kAPhase space

[MeV]E

0.9 [μm]projx

8 [μm]projy


[μm]x

[μm]y

[μm]s [μm]s

85fs

[kA]I

-20 0 20 40

14.002

14.004

14.006

14.008

14.01

14.012

14.014E


Strong Compression

Parameter UnitBunch charge nC 1

Peak current (gun) A 43Compression 116 228Peak current kA 5 9.8

Bunch length (FWHM) fs 178 75Slice emittance mm 1 1

Projected emittance mm 3.5 8Slice energy spread (laser heater off)

MeV 0.45 1

Q=1 nC


Strong Compression for 250 pC

[MeV]E

[kA]I

[μm]s

[μm]s [μm]s

[μm]s

[MeV]E

[kA]I

R56,3= -20 mm R56,3= -23.8 mm



Momentum compaction

factor in BC1

R56,1,[mm]

Compr.in BC1

C1

Momentum compaction

factor in BC2

R56,2,[mm]

Compr.in BC2

C2

Momentum compaction

factor in BC3

R56,3,[mm]

Totalcompr.

C

Second derivative

(C-1)'',[m-2]

-78 3.5 -50 8 -20,…,-24 385 1000

Macro-parameters

1 130MeVE 2 700 MeVE 3 2400MeVE



-10 0 10 20

13.995

14

14.005

14.01

-20 -10 0 10 20 300

0.5

1

1.5

R56,3=-20mm

5kAI

Phase space

[MeV]E


[μm]x

[μm]y

[μm]s [μm]s



-20 -10 0 10 20 300

1

2

3

-10 0 10 20

13.935

13.94

13.945

13.95

13.955

R56,3 =-21 mm

5kAI

Phase space

[MeV]E


[μm]x

[μm]y

[μm]s [μm]s



-10 0 10 200

2

4

6

8

10

[MeV]E-5 0 5 10 15

13.9

13.92

13.94

13.96

13.98

5kAI

[MeV]E

[μm]x

[μm]y

[μm]s [μm]s

R56,3 =-21.9 mmPhase space Current, emittance, energy spread



-5 0 5 10 150

2

4

6

8

0 5 10

13.92

13.93

13.94

13.95

13.96

13.97

5kAI

[MeV]E

[μm]x

[μm]y

[μm]s [μm]s

R56,3 =-22.6 mmPhase space Current, emittance, energy spread



-4 -2 0 2 40

1

2

3

4

5

-2 -1 0 1 2

13.92

13.93

13.94

13.95

13.96

13.97

5kAI

[MeV]E

[μm]x

[μm]y

[μm]s [μm]s

R56,3 =-22.6 mm (70% of particles)Phase space Current, emittance, energy spread



-10 -5 0 5 100

0.5

1

1.5

2

2.5

-4 -2 0 2 413.98

13.99

14

14.01

14.02

5kAI

[MeV]E

[μm]x

[μm]y

[μm]s [μm]s

R56,3 =-23.2 mm (70% of particles)Phase space Current, emittance, energy spread


Strong Compression for 250 pCBeam core parameters vs. R56

20 21 22 23 240

10

20

30

40

50

20 21 22 23 240

5

10

15

20

25

20 21 22 23 240.2

0.3

0.4

0.5

0.6

20 21 22 23 240

1

2

3

4

[kA]I

[μm]slicex [μm]slice

y

[fs]t

56,3 [mm]R56,3 [mm]R

56,3 [mm]R56,3 [mm]R

70% of particles



20 21 22 23 240

2

4

6

8

20 21 22 23 24

0.35

0.4

0.45

0.5

0.55

0.6

0.65

20 21 22 23 240

2

4

6

8

20 21 22 23 240

10

20

30

40

50

[kA]I [MeV]E

[μm]y[μm]x

56,3 [mm]R

56,3 [mm]R

56,3 [mm]R

56,3 [mm]R

70% of particles

Beam core parameters vs. R56



0 50 100 1500

0.5

1

1.5

2

2.5

3[mJ]E

[m]z

56.3 20mmR

56.3 21.6mmR

Radiation energy vs. R56 (with und. wake and taper)

20 21 22 23 240

0.2

0.4

0.6

0.8

1

1.2

1.4

60mz

[mJ]E

[a.u.]I

56,3 [mm]R


Strong Compression (SLAC)

0.15 50.03

Q=20 pC



Radiation energy vs. compression rate

20 21 22 23 240

0.2

0.4

0.6

0.8

1

1.2

1.4

60mz

[mJ]E

[a.u.]I

56,3 [mm]R



20 21 22 23 240

0.2

0.4

0.6

0.8

1

1.2

1.4

60mz

[mJ]E

[a.u.]I

56,3 [mm]R

0.15 50.03

1 6

0.16

Radiation energy vs. compression rate



20 21 22 23 240

100

200

300

400

500

600

700175mz

[a.u.]I

56,3 [mm]R20 21 22 23 24

0

50

100

150

20060mz

max[GW]P

[a.u.]I

max[GW]P

56,3 [mm]R

Radiation power vs. compression rate


Summary

Bunches with charge 20-1000 pC can be compressed to 5 kA and higher

Radiation energy drops down at “full” compression

Overcompression scenario can be used

Acknowledgements to M.Dohlus and T.Limberg for many useful discussions

Documents

Charge and Bunch Length Scope