Beam Energy Spread for HGHG

in FLASH2

Igor Zagorodnov DESY, Hamburg, Germany

22.04.2010

S2E Meeting

Technical constraints and beam parameters

I > 1kA

∆ > 200 fs 0.2nCQ I

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

Energy spread < 120keV

ASTRA+CSRtrack

Energy spread vs. charge?

Charge

Q,

nC

Energy

in BC2

E1,

[MeV]

Energy

in BC3

E2,

[MeV]

Deflecting

radius in BC2

teta1,

[grad]

Deflecting

radius in BC3

r2,

[m]

Compression

in BC2

C1

Total

compression

C

First

derivative

Z2',

[m-1]

Second

derivative

Z2'',

[m-2]

1

130

450

15

4.78 2.84 48 1 2e3

0.5 4.14 4.63 90 1 3.5e3

0.25 3.68 6.57 150 0.7 4e3

Igor Zagorodnov and Martin Dohlus,

Beam Dynamics and FEL Simulations for FLASH,

08.02.2010,Beam Dynamics Meeting, DESY

http://www.desy.de/fel-beam/data/talks/files/IZ_2010_February.pdf

-3000 -2000 -1000 0 1000 2000 30000

0.5

1

1.5

2

2.5

-30 -20 -10 0 10 20 3050

100

150

200

250

300

Energy spread vs. charge?

[μm]s[μm]s

Slice emittance [um] Slice energy spread [keV]

1nCQ 0.5nCQ 0.25nCQ

-4000 -2000 0 2000 40000

0.5

1

1.5

2

2.5

3

3.5

-4000 -2000 0 2000 4000

0.6

0.8

1

1.2

1.4

1.6

1.8

E in BC 2 = 130 MeV, ACC1(40%, 60 %)

E in BC 2 = 145 MeV, ACC1 (50%, 50 %)

E in BC 2 = 145 MeV, ACC1 (37.5%, 62.5 %)

Energy spread after ACC1 (z=14.61 m) for Q=1nC

Slice emittance [um] Slice energy spread [keV]

[μm]s [μm]s

Charge

Q,

nC

Energy

in BC2

E1,

[MeV]

Energy

in BC3

E2,

[MeV]

Deflecting

radius in BC2

teta1,

[grad]

Deflecting

radius in BC3

teta2,

[grad]

Compression

in BC2

C1

Total

compression

C

First

derivative

Z2',

[m-1]

Second

derivative

Z2'',

[m-2]

1 130 450 18 4.5 4 26 0 0

S2E (up z = 152 m ) for Q=1nC

-150 -100 -50 0 50 100 1500

50

100

150

-150 -100 -50 0 50 100 1500

20

40

60

80

100

-150 -100 -50 0 50 100 1500

20

40

60

80

100

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

Energy spread after ACC7 (z=152 m) for Q=1nC

[μm]

26

s

26 [keV]E26 [keV]E

[μm]

26

s

6.5 [keV]E

[μm]

6.5

s

6.5 [keV]E

[μm]

6.5

s

-150 -100 -50 0 50 100 1500

20

40

60

80

100

120

140

160

180

-150 -100 -50 0 50 100 1500

50

100

150

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

6.5 [keV]E

[keV]E

[μm]

6.5

s[μm]s

[keV]E

[μm]s

Energy spread after ACC7 (z=152 m) for Q=1nC

-150 -100 -50 0 50 100 1500

50

100

150

6.5 [keV]E

[μm]

6.5

s25.3[m]z

26 28 30 32 34 36 38 400

2

4

6

8

10

12

[m]z

[m]y

3D(MATLAB)

2D(ASTRA)

3D(ASTRA)

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

S2E (up z = 152 m ) for Q=1nC

[kA]I

[μm]y

[keV]

100

E

[μm]s

[μm]x

330fs

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

660fs

2D(ASTRA)3D(ASTRA)

[μm]s

S2E for FLASH2 line (Q=1nC)

-100 -50 0 50 100 150994

996

998

1000

1002

1004

ASTRA+CSRtrack

Elegant

?

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

S2E for FLASH2 line at z=194 m (Q=1nC)

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

[kA]I

[μm]y

[keV]

100

E

[μm]s

[μm]x

360fs

200k particles (3D ASTRA) 1000k particles (3D ASTRA)

S2E for FLASH2 line at z=194 m (Q=1nC)

-100 -50 0 50 100 150994

996

998

1000

1002

1004

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

[kA]I

[μm]y

[keV]

100

E

[μm]s

[μm]x

360fs

1) the global slice length: ~15 um slice = 50 fs

- Slippage in Modulator ~ 4 um

- Slippage in Radiator ~10 um

* Within this slice, the energy spread should be smaller

than 100 keV

2) min current along the global slice: Should exceed at

least 0.5 kA

3) how large can be the variation of the current along the

global slice:

most important to assure min. 0.5 kA.

4) maximal local slice emittance along the global slice?:

1.5 um

5) maximal local (uncorrelated) energy spread: ~100 keV

6) maximal energy chirp (correlated energy spread) along

the global

slice? ~150 keV

S2E for FLASH2 line at z=194 m (Q=1nC)

-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

[kA]I

[keV]

100

uncorr

E

[μm]s-150 -100 -50 0 50 100 1500

0.5

1

1.5

2

2.5

slice 15um[keV]

100

E

slice 10um[keV]

100

E

[μm]s

energy spread in slice of length 10 um

and 15 um uncorreleted energy spread