CALCULATIONS OF THE LCLS INJECTOR USING ASTRA Jean-Paul Carneiro DESY Hamburg ICFA Future Light Sources Sub-Panel Mini Workshop on Start-to-End Simulations

CALCULATIONS OF THE LCLS INJECTOR USING ASTRA

Jean-Paul CarneiroDESY Hamburg

ICFA Future Light Sources Sub-PanelMini Workshop on

Start-to-End Simulations of X-RAY FELsDESY Zeuthen, 18 August 2003

LCLS ACCELERATOR SCHEMATIC

Jean-Paul Carneiro CALCULATIONS OF THE LCLS INJECTOR USING ASTRA

…existing linac

Linac-1L = 9 m

Linac-2L = 330 m

Linac-3L = 550 m

Linac-XL = 0.6 m

BC 1 BC 2

%10.0σ

mm83.0zσ

MeV 150

%8.1σ

mm19.0zσ

MeV 250

%076.0σ

mm022.0zσ

GeV 4.54

%02.0σ

mm022.0zσ

GeV 14.5

%2.0σ

mm83.0zσ

MeV 7

UndulatorL = 120 m

From LCLS Conceptual Design Report

RF GUN

L01

L02

35 Deg

LCLS INJECTOR



RF GUN (SUPERFISH SIMULATIONS)

0 0.05 0.1 0.15-1

-0.5

0

0.5

1

Z [m]

No

rma

lize

d E

z

15 cm

4.2 cm

RF GUN PARAMETERS

• 1.6 cells, π-mode, 2856 MHz• 120 MV/m, ~ 9 MW• 120 Hz, ~ 3 µs• symmetric RF gun, 1 µm at 1.0 nC

CATHODE

• Cu (possibly Mg)• 12 mm usable diameter, QE > at 263 nm510


SOLENOIDS (POISSON SIMULATIONS)

0 0.5 1 1.5 2 2.5 3-0.5

0

0.5

1

Z [m]

No

rma

lize

d B

z

• Emittance compensating solenoid : max Bz = 0.27235 T at 18.9 cm• L01 solenoid : max Bz = 0.748 T


ASTRA

• For PARMELA / ASTRA comparisons : 30 000 particles

• For ELEGANT input : 200 000 particles, 12 digits

• Space charge calculation : N_rad = 20, N_long=60 N_rad = 60 µm, N_long=50 µm, automatic adjustment of the mesh with the bunch.

• Increment step : min = 0.1 ps and max = 5 ps. Automatic adjustment of the increment step.


LCLS LASER (ASTRA GENERATOR OUTPUTS, 2E5 p.)

-10 -5 0 5 100

500

1000

1500

2000

2500

3000

Time [ps]

Po

pu

latio

n

• Transverse distribution : uniform, r = 1.2 mm• Longitudinal distribution : uniform, L=10 ps with 0.7 ps rise times• Thermal emittance : 0.6 mm-mrad per mm radius (Cu cathodes)

From TELSA-FEL 97-01 (K. Floettmann) : eV1038.13

12

2 20

,

kinkin

rmsn Ecm

Er

Longitudinal distribution Transverse distribution


PHASE SCAN OF LCLS AND TESLA XFEL WITH ASTRA

• LCLS: 120 MV/m, 0.27235 T, L= 10 ps + 0.7 ps rise time, r = 1.2 mm• TESLA XFEL : 40 MV/m, 0.163 T, L = 20 ps + 3 ps rise time, r =1.5 mm

-10 -5 0 5 100

0.2

0.4

0.6

0.8

1

RF GUN LAUNCH PHASE [DEG]

CH

AR

GE

[nC

]

SPACE CHARGE OFFSPACE CHARGE ON

SPACE CHARGE ON & OFFZERO-CROSSING = - 6 DEG

-10 -5 0 5 100

0.2

0.4

0.6

0.8

1

RF GUN LAUNCH PHASE [DEG]

CH

AR

GE

[nC

]

SPACE CHARGE OFFSPACE CHARGE ON

SPACE CHARGE ONZERO-CROSSING = - 5 DEG


LONG. PHASE SPACE AT GUN EXIT (15 CM)

• Phase laser in ASTRA (and PARMELA) : + 32 Deg

HEAD

TAIL

HEAD

TAIL

ASTRA GUN FIELD = 120 MV/m ASTRA GUN FIELD = 120.15 MV/m

GUN EXIT (15 CM)



GUN EXIT (15 CM)

0 0.05 0.1 0.150

10

20

30

40

50

Z [m]

En

erg

y S

pre

ad

[%]

PARMELAASTRA

0 0.05 0.1 0.150

1

2

3

4

5

Z [m]

En

erg

y S

pre

ad

[%]

PARMELAASTRA


GUN EXIT (15 CM)

0 0.05 0.1 0.150

1

2

3

4

5

Z [m]

RM

S N

orm

. Em

it. X

[mm

-mra

d]

PARMELAASTRA

0 0.05 0.1 0.150

0.5

1

1.5

2

Z [m]

RM

S S

ize

X [m

m]

PARMELAASTRA


GUN EXIT (15 CM)

0 0.05 0.1 0.150

0.2

0.4

0.6

0.8

1

Z [m]

RM

S B

un

ch L

en

gth

[mm

]

PARMELAASTRA

0 0.05 0.1 0.150

1

2

3

4

5

6

7

Z [m]M

om

en

tum

[Me

V/c

] PARMELAASTRA


GUN EXIT (15 CM) – RESUME

UNITS ASTRA PARMELA

MOMEMTUM [MeV/c] 6.1408 6.15

RMS ENERGY SPREAD [%] 0.43 0.37

RMS SIZE X or Y [mm] 1.69 1.78

RMS NORM. EMIT X or Y [mm-mrad] 2.49 2.97

RMS BUNCH LENGTH [mm] 0.80 0.78

• PARMELA and ASTRA with 30 000 particles • PARMELA & ASTRA : 120 MV/m, 0.27235 T, L =10 ps + 0.7 ps rise time, r =1.2 mm

0.15%

14%

5%

16%

2%


ACCELERATING SECTIONS L01 & L02

0 0.05 0.1 0.15 0.2 0.25-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Z [m]

No

rma

lize

d E

z

• L01 & L02 : 3 m S-Band sections, 84 cells per section, TWS• L01 located at 1.4 m and L02 at 5.4 m (from photo-cathode)

• PARMELA : uses TRWAVE for L01 & L02, with product of the average axial electric field in MV/m and the transit-time time factor T. For L01 : and for L02:

• ASTRA : uses the maximum field of the TW Emax

• From SUPERFISH :

TE0

0E MV/m 18 TE0 MV/m 30.5 TE0

MV/m 20Emax ----- MV/m 18 TE0

MV/m 40.66 Emax - - - - - MV/m 30.5 TE0

Superfish simulation of one TW cell

0 2 4 6 8 100

20

40

60

80

100

120

140

160

Z [m]

Mo

me

ntu

m [M

eV

/c]

PARMELAASTRA

ENERGY GAIN ALONG LCLS INJECTOR


PARMELA : 149.96 MeV/cASTRA : 149.14 MeV/c (0.5 %)


EXIT L01(4.46 M)

HEAD

TAIL

HEAD

TAIL

MAX FIELD L01 = 24.0 MV/m MAX FIELD L01= 24.025 MV/m

Long. Phase Space for 3 phases of L01 Phase ASTRA L01 at +5.5 Deg


EXIT L01(4.46 M)


EXIT L02 (8.42 M)

HEAD

HEAD

TAIL TAIL

MAX FIELD L02 = 40.66 MV/m MAX FIELD L02 = 40.68 MV/m

Long. Phase Space for 3 phases of L01 Phase ASTRA L01 at -2.5 Deg


EXIT L02 (8.42 M)


EMITTANCE & SIZE ALONG LCLS INJECTOR

0 2 4 6 8 100

1

2

3

4

5

Z [m]

RM

S N

orm

. Em

it. X

[mm

-mra

d]

PARMELAASTRA

0 2 4 6 8 100

0.5

1

1.5

2

2.5

Z [m]

RM

S S

ize

X [m

m]

PARMELAASTRA


0 2 4 6 8 100

0.5

1

1.5

2

Z [m]

En

erg

y S

pre

ad

[%]

PARMELAASTRA

ENERGY SPREAD & BUNCH LENGTH ALONG LCLS INJECTOR

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

Z [m]

RM

S B

un

ch L

en

gth

[mm

]

PARMELAASTRA

Jean-Paul Carneiro ASTRA SIMULATIONS OF THE LCLS INJECTOR

EXIT L01 (4.46 M) – RESUME

UNITS ASTRA PARMELA



RMS SIZE X [mm] 0.32 0.35

RMS NORM. EMIT X [mm-mrad] 1.01 0.94

RMS SIZE Y [mm] 0.32 0.35

RMS NORM. EMIT Y [mm-mrad] 1.01 0.94


(0.22%)

(4%)

(0.35%)

(7%)

(10%)

(7%)

(3%)


EXIT L02 (8.42 M) – RESUME

UNITS ASTRA PARMELA



RMS SIZE X [mm] 0.32 0.29

RMS NORM. EMIT X [mm-mrad] 0.98 0.96

RMS SIZE Y [mm] 0.32 0.29

RMS NORM. EMIT Y [mm-mrad] 0.98 0.96


(0.5 %)

(6%)

(10%)

(2 %)

(10%)

(2 %)

(2%)


DISTRIBUTION AT 9.4 M ( FOR ELEGANT)

-2 -1 0 1 20

20

40

60

80

100

120

Z [mm]

Cu

rre

nt [

A]

PARMELAASTRA

-2 -1 0 1 20

0.5

1

1.5

2

2.5

3

3.5

Z [mm]E

mitt

an

ce [m

-ra

d]

PARMELA XPARMELA YASTRA XASTRA Y

• Comparison ASTRA output at 9.4 m with elegant input of S2E workshop …

HEAD

TAIL

HEADTAIL


DISTRIBUTION AT 9.4 M ( FOR ELEGANT)

-2 -1 0 1 20

0.02

0.04

0.06

0.08

0.1

Z [mm]E

ne

rgy

Sp

rea

d

PARMELAASTRA

-2 -1 0 1 2148.5

149

149.5

150

150.5

151

Z [mm]

Mo

me

ntu

m [M

eV

/c]

PARMELAASTRA

HEAD

TAIL

HEAD

TAIL


CONCLUSION

• GOOD AGREMENT BETWEEN ASTRA AND PARMELA FOR THE LCLS INJECTOR

• JITTER STUDIES NEED TO BE DONE

Documents

CALCULATIONS OF THE LCLS INJECTOR USING ASTRA Jean-Paul Carneiro DESY Hamburg ICFA Future Light Sources Sub-Panel Mini Workshop on Start-to-End Simulations