Transcript Document

Free-Electron Laser at the TESLA Test Facility
XFEL simulations with GENESIS
[email protected]
Outline:
•Undulator layout (real/simulated)
•Matching
•Genesis input files
•Post-processing
•Genesis output
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Undulator description: real
Matching
section
Ls
L
Undulator segment
c
Phase shifter combined with horizontal corrector
Focusing
Defocusing quadrupole
Parameters
Symbol
Value
Unit
Undulator segment length
Ls
5
m
Undulator cell length
Lc
6.1
m
Undulator gap
g
10
mm
lu
48
mm
192
mm
20
T/m
Undulator period (SASE1)
Quadrupole optical length
Quadrupole gradient at 20 GeV
B. Faatz
Vertical corrector
Q
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Undulator description: simulated
Undulator segment
Focusing
Defocusing quadrupole
• Increased quadrupole length in order to increase stepsize (adjusted gradient)
• Automatic phase matching between undulators
Actual undulator geometry is defined in the magnet lattice file
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Matching at the undulator entrance
Electron beam information starts with output from Elegant
(In this example until the undulator entrance with 200k particles)
Elegant2genesis (SDDS toolkit)*
•Check # slices/# particles per slice
•Adjust initial a and b for optimal slice
•Adjust initial offset and angle for optimal slice
•Add wakefield along the undulator
1e-9
100
*elegant2genesis <input.file> <output.file> -totalCharge= <charge> -slices= <#slices>
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Genesis input
•E-beam slice file (Elegant2genesis+match)
•“Elegant2genesis” produces global beam parameters for each slice
•“match” adjusts <x>, <y> and <x’>, <y’> for slice with maximum current
•Magnetic lattice file
•Genesis namelist input (Numerical and IO-parameters, …)
From global parameters, Genesis fills the 5D+1 phase
space with a Gaussian distribution
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
20
40
12
60
80
Input distribution
100
Normalized emittance (mm mrad)
0
Slice number
Current (A)
10
8
6
4
Tail of the bunch
2
0
-150
-125
-100
-75
-50
-25
0
25
50
4
x
2
1
0
-150
75
y
3
-125
-100
-75
s (m)
-50
-25
0
25
50
75
s (m)
20.536
<x>
<y>
20.534
Large betatron oscillation
1.5
20.532
Energy (GeV)
150
2.0
100
50
0
20.530
1.0
20.528
20.526
0.5
20.524
20.522
-50
0.0
20.520
-100
-150
-125
-100
-75
-50
-25
0
25
50
75
-150 -125 -100
-50
-25
0
25
50
75
s (m)
s (m)
B. Faatz
-75
S2E workshop, August 18-22, 2003
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Energy spread (MeV)
Beam centroid position (m)
200
Free-Electron Laser at the TESLA Test Facility
Post-processing
•Xgenesis (IDL)
•Interactive (GUI)
•Gen2Spread: Separate Genesis output file
•In slices along undulator
•At different undulator position temporal profile
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Steady state results: no wakefields
Unmatched angle/offset
Matched angle/offset
20
0.020
10
18
1
0.1
16
0.015
0.01
1E-3
14
1E-4
Power (GW)
Power (GW)
1E-5
0.010
0.005
12
0
20
40
60
80
100
10
8
6
4
2
0
10
20
30
40
50
60
70
80
90
0
100 110
10
20
30
40
50
60
70
80
90
100 110
slice number
slice number
2
10
0.30
1
10
0.25
0
Bunching
Power (GW)
10
-1
10
-2
10
0.20
0.15
-3
10
0.10
-4
10
0.05
-5
10
0
50
100
150
200
0.00
0
z (m)
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50
100
150
200
z (m)
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Energy loss due to the wakefield*
12
0.1
0.0
8
6
-0.1
4
2
wake (MV/m)
Current (A)
10
-0.2
0
-150 -125 -100
-75
-50
-25
0
25
50
75
s (m)
assumed an inner radius of 4 mm copper coated stainless steel
*resistive wall wake only
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Steady state results: including wakefields (matched)
Including taper
Without taper
100
1.4
2
10
0
10
1
10
0
10
-1
10
1.2
-1
10
80
-2
10
-2
10
-3
10
-3
10
-4
1.0
10
-4
10
-5
10
-5
0
20
40
60
80
Power (GW)
Power (GW)
10
100
0.8
0.6
0.4
-6
10
60
0
20
40
60
80
100
40
20
0.2
0.0
0
0
20
40
60
80
100
0
20
40
60
80
100
slice number
slice number
2
10
0.35
1
10
0
0.30
-1
0.25
10
Bunching
Power (GW)
10
-2
10
-3
10
-4
10
0.20
0.15
-5
0.10
-6
0.05
10
10
-7
10
0
50
100
150
200
0.00
0
z (m)
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50
100
150
200
z (m)
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Time dependent simulations: no wakefields
12
NSLICE
Current (A)
10
8
6
4
NTAIL
2
0
-150
-125
-100
-75
-50
-25
0
25
50
75
s (m)
Part of the bunch selected for time dependent simulations
Simulate 20000 photon slices to assure overlap, 8000 particles each
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
70 GW power, 3m FWHM pulse (10 fs)
280
100
10
240
1
0.1
Power (GW)
200
0.01
0
10
20
30
40
50
160
120
80
40
0
0
10
20
30
40
50
s (m)
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Frequency spectrum
?
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
17000
Beam centroid position (m)
12
10
Current (A)
40
8
6
4
2
0
-150
-125
-100
-75
-50
-25
0
25
50
32
<x>
<y>
24
16
8
0
-8
-16
-24
-32
-40
75
0
s (m)
50
150
50
80
40
Beam size (m)
100
60
40
30
20
xrms
yrms
20
10
0
0
50
100
z (m)
200
z (m)
120
Power (GW)
100
150
200
0
0
50
100
150
200
z (m)
B. Faatz
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
17500
Beam centroid position (m)
12
10
Current (A)
8
6
4
2
0
-150
-125
-100
-75
-50
-25
0
25
50
75
4
<x>
<y>
2
0
-2
-4
s (m)
0
50
100
150
200
z (m)
120
50
80
Beam size (m)
Power (GW)
100
60
40
20
0
40
30
20
xrms
yrms
10
0
50
100
z (m)
B. Faatz
150
200
0
0
50
100
150
200
z (m)
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
18000
12
Beam centroid position (m)
Current (A)
10
8
6
4
2
0
-150
-125
-100
-75
-50
-25
0
25
50
75
s (m)
50
100
150
200
z (m)
100
50
80
Beam size (m)
Power (GW)
<x>
<y>
0
120
60
40
20
0
28
24
20
16
12
8
4
0
-4
-8
-12
-16
-20
-24
-28
40
30
20
xrms
yrms
10
0
50
100
150
200
0
0
z (m)
B. Faatz
50
100
150
200
z (m)
S2E workshop, August 18-22, 2003
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Free-Electron Laser at the TESLA Test Facility
Conclusion
Much more work needs to be done
Extend time window
Get frequency information
Include all wakes, quantum fluctuations, …
B. Faatz
S2E workshop, August 18-22, 2003
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