genesis simulations with wakefields for xfel
DESCRIPTION
GENESIS simulations with Wakefields for XFEL. Igor Zagorodnov BDGM, DESY 26.09.05. SASE 2 parameters. Parameters XFEL theory. Parameters XFEL theory. Gain parameter. Efficiency parameter. Diffraction parameter. Effective power of the input signal. Gain length *. Optimal beta-function. - PowerPoint PPT PresentationTRANSCRIPT
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GENESIS simulations with Wakefields for XFEL
Igor Zagorodnov
BDGM, DESY
26.09.05
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name symbol unit value
energy GeV 17.5
energy spread MeV 1.5
emmitance n mm-mrad 1.4
bunch charge Q nC 1
bunch length m 25
peak current IP kA 4.76
undulator period u cm 4.8
undulator parameter au 2.33
quadrupole length LQ cm 20
quadrupole gradient GQ T/m 17
section length Lsect m 5+1.1
total length Ltotal m 260
beta function (waist)x,
y,
m41.6
29.3
SASE 2 parameters
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Parameters XFEL theory
22
1 0.13155[nm]2
us ua
, ,
41[ ]
34n
x y x y m
2 20 2
67 [ ]rR
s s
wz m
0.5( ) 37 [ ]r x y m
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Parameters XFEL theory
1/ 22
3 0.52 [ ]2
JJ s l P
l A
A Icm
c I
1/31 3 0.16 [ ]B cm
23 34s
rBc
21
1 6.1e-4lc
2
33 20e-4lc
Gain parameter
Efficiency parameter
Diffraction parameter
Effective power of the input signal
13 6444 [ ]lnb
sh
c c
WP W
N N
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Gain length*
0 (1+ ) 14 [m]g gL L
31[m]opt
Optimal beta-function
010 = 140 [m]sat gL L
Saturation length
* E.L.Saldin et al./Optics Communications 235 (2004) 415-420
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0.13175 [nm]nums
22
1 0.13155[nm]2
us ua
Genesis steady state simulation
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1 1.2 1.4 1.6 1.8
x 10-4
-10
-5
0
5x 10
4
head tail
Loss,
kV/nC/m
Spread,
kV/nC/m
Peak,
kV/nC/m
total 48 47 -101
-0.01 -0.005 0 0.005 0.01
-100
-50
0
||
kVW
nC m
[ ]s cm
.geom
.res
[ ]s m
headtail
||
VW
nC m
bunch
wakeELOSS= = - 48keV/m
-1 -1: 5.8e+7[ m ], =2.46e-14[sec]cond relaxcu
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Scan with ELOSS = - 48keV/m
0.13180 [nm]0.13175 [nm]nums
Genesis steady state simulation
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[m]z
[ m]s
Power
no wake (amplifier)
with wake (amplifier)
no wake (SASE)
with wake (SASE)
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Genesis time dependent simulation
0 50 1000
1
2
3x 10
10
250
250
0.2wake
m
m
P
P
250
250
0.4wake
m
m
P
P
Amplifier model SASE model
75mmax0.13165 [nm](P )num
s 250mmax0.13175 [nm] (P )num
s
[ m]s
[W]P
0 50 1000
1
2
3x 10
10
no wake
with wake
[ m]s
[W]P
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Taper optimization (steady state)
13 3 5w
w
ae
a
0 10 20 300
1
2
3
4
410 /w wa a
10250 [10 ]mP W Scan with ELOSS = - 100keV/m
2
0.019 ,0.048
5.068 3.04 80 ( )
w
w
w w w g mm
a B g g gg m
a B g
sec/ 0.9μm/sectiong N 3.694exp( (5.068 1.520 ))u u
g gB
37.5g m
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0 50 1000
2
4
6
x 1010
0 50 1000
1
2
3x 10
10
Genesis time dependent simulation
with wake
250
250
0.4wake
m
m
P
P
SASE model
250
250
2wake taper
m
m
P
P
no wake
no wake
wake taper
[ m]s
[W]P
[ m]s
[W]P
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Power (Gaussian bunch)
1 1.2 1.4 1.6 1.8
x 10-4
-10
-5
0
5x 10
4
||
kVW
nC m
[ ]s cm
no wake with wake wake+taper[ ]z m
[ ]s m1800 1800 1800
[ ]s m [ ]s m
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4 6 8 10 12
x 10-5
-1
0
1
x 105
2 4 6 8 10
x 10-5
-1
0
1
x 105
-5 0 5
x 10-5
-1
-0.5
0
0.5
1x 10
5Shape 0
Shape 3
head tail
headtail
.geom
.resist
headtail
-1 -1: 5.8e+7[ m ],
=2.46e-14[sec]cond
relax
cu
||
VW
nC m
[ ]s m
„Real“ shapes from Martin Dohlus
http://www.desy.de/~dohlus/2005.09.xfel_wakes
( ) ( )geomhiW s cZ s
3.36[ / ]hiZ m
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Geometric wake?
pro section (6.1 m)
Loss,
V/pC
absorber 1 42
pumping slot 1 <0.2
pump 1 9
BPM 1
bellow 1 13
flange gap 1 6
Total geom. 70
Longitudinal wake for the case of the elliptical pipe (3.8mm)
-0.01 -0.005 0 0.005 0.01
-100
-50
0
||
kVW
nC m
[ ]s cm
( ) ( )geomhiW s cZ s
3.36[ / ]hiZ m The wake repeats the bunch shape
.geom
.resist
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Genesis time dependent simulation (SASE)
250
0250
0.41gauss
m
shapem
P
P
0 50 1000
2
4
6
x 1010
0 50 1000
1
2
3x 10
10
3250
3250
0.15shape wake
m
shapem
P
P
3250
3250
1shape wake
m
shapem
P
P
250
250
0.4gauss wake
m
gaussm
P
P
250
250
2gauss wake
m
gaussm
P
P
Gaussian Shape 3
[ m]s
[W]P
[ m]s
[W]P
with wake
wake taper
no wake
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Power
1 1.2 1.4 1.6 1.8
x 10-4
-10
-5
0
5x 10
4
4 6 8 10 12
x 10-5
-1
0
1
x 105
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Genesis time dependent simulation (SASE)
250
0250
0.78gauss
m
shapem
P
P
0 50 1000
2
4
6
x 1010
0250
0250
0.37shape wake
m
shapem
P
P
0250
0250
1.4shape wake
m
shapem
P
P
250
250
0.4gauss wake
m
gaussm
P
P
250
250
2gauss wake
m
gaussm
P
P
Gaussian Shape 0
0 50 1000
1
2
3
4x 10
10
[ m]s
[W]P
[ m]s
[W]P
with wake
wake taper
no wake
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Free space
With
wake
With
wake+taper
(32mkm / 260m)
Gaussian 1 0.4 2
Shape 0 0.8 0.8*0.37=0.3 0.8*1.4=1.1
Shape 3 0.4 0.4*0.15=0.06 0.4*1=0.4
Gaussian Shape 0 Shape 3
Power in a.u.
0 50 1000
2
4
6
x 1010
0 50 1000
2
4
6
x 1010
0 50 1000
2
4
6
x 1010
[ m]s
250 [W]mP
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0 50 1000
2
4
6
x 1010
0.8 1 1.2 1.4 1.6
x 10-4
-1
0
1
x 105
4 6 8 10 12
x 10-5
-1
0
1
x 105
2 4 6 8 10
x 10-5
-1
0
1
x 105
Gaussian Shape 0 Shape 3
||
VW
nC m
[ ]s m
bunch
wake
0 50 1000
2
4
6
x 1010
0 50 1000
2
4
6
x 1010
[ m]s
250 [W]mP
13 3 5w
w
ae
a
wake taper
no wakewith wake
wake taper
wake taper
Taper:
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Power
Gaussian
Shape 0
Shape 3
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Conclusions
1. The wake field reduces the power at L=250 m by factor 2.5 for the Gaussian bunch and up to factor 7 by the “real” shape
2. The linear taper allows to avoid the degradation and to increase the power by factor 2 for the Gaussian bunch
Acknowledgements to Evgeny Schneidmiller and Martin Dohlus for the help
3. The same taper allows to avoid the degradation for other shapes too