Transcript Slide 1

Status of the Simulations on
Photo Injector Optimization for
Low Charges
Yauhen Kot
BD Meeting, 01.02.2010
Preliminary results
work is not accomplished yet…
Optimization Code for the Photo Injector by M. Krasilnikov
FLASH Photo Injector
Booster phase is fixed
Same gradient at booster and ACC1
Gun
Booster
ACC1
3,9GHz
Optimization Code for FLASH Photo Injector
Ez1(z=0)=45MV/m
+ Bucking coil peak field
Field Files for the Gun
Slightly different files but big consequencies
Tuning parameters for efld
hor
vert
Tuning parameters for FLASHgun_p12
hor
vert
Beam size
XYrms
0.170105
e
0.3278
0.3273
Beam size
XYrms
0.15929
e
0.3131
0.3128
Solenoid
MaxB(1)
0.172724
0.2988
0.2982
Solenoid
MaxB(1)
0.171247
0.2949
MaxB(2)
0.019489
MaxB(2)
0.015844
b
37.52
38.48
Bucking
Coil
e
reduced
0.2949
Bucking
Coil
e
reduced
b
44.97
45.87
Gun
MaxE(1)
45.00
a
-2.204
-1.792
Gun
MaxE(1)
45.00
a
-2.873
-2.350
Phi(1)
-1.34264
Phi(1)
-1.27222
MaxE(2)
40.12
MaxE(2)
40.12
Phi(2)
-14.85
Phi(2)
-14.85
Booster
Booster
efld.dat
FLASHgun_p12.dat
Calculated with best parameters for efld.dat. Comparison
efld
FLASHgun_p12
bx
37.52
e
0.3266
20.61
e
0.6356
38.48
e reduced
bx
by
0.2988
by
21.56
e reduced
0.4374
ax
-2.204
ax
-0.509
ay
-1.792
ay
-0.273
Tuning Parameters
Field File efld.dat
Charge
XYrms
Gun Phase, Phi(1)
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
0.105
0.070
0.071
-0.945
-0.231
-0.289
0.040
0.111
0.101
0.103
-0.491
-0.565
-0.523
0.100
0.183
0.1741
0.170
-1.435
-1.519
-1.348
Charge
Solenoid MaxB(1)
Bucking Coil, MaxB(2)
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
0.1702
0.1723
0.1720
0.0672
0.0069
0.0157
0.040
0.1729
0.1720
0.1724
0.0202
0.0231
0.0148
0.100
0.1740
0.1740
0.1741
-0.0381
-0.034
-0.0221
Charge
Booster gradient, MaxE(2)
Booster phase, Phi(2)
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
34.638
39.83
39.60
0.887
0.339
1.422
0.040
22.271
39.83
36.88
0.867
-0.718
0.115
0.100
34.583
34.40
39.60
0.180
0.362
-0.078
- Booster gradient and phase were considered as parameters to be optimized
- Best value for booster gradient was found in the near of the desired 40.12MeV almost in all cases
- Booster Phase seems not to affect the emittance significantly
- Results after ~50 Iterations with Optimization Code with 2000 particles
Results after Booster at s=9.0m
Field File efld.dat
Charge
Emittance
Bunch length
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
0.180
0.133
0.126
0.642
1.112
1.254
0.040
0.254
0.194
0.189
0.938
1.222
1.342
0.100
0.533
0.358
0.317
1.087
1.336
1.478
Charge
Energy rms
momentum
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
44.85
66.41
115.6
79.92
91.19
90.65
0.040
60.65
56.88
78.24
52.97
91.21
84.76
0.100
88.08
98.39
100.8
79.77
79.35
90.65
Charge
Beta
Alpha
1.1ps
3.3ps
4.4ps
1.1ps
3.3ps
4.4ps
0.020
9.87
31.22
22.93
-1.435
-4.393
-3.292
0.040
88.76
19.95
15.46
-10.80
-3.073
-2.332
0.100
17.57
11.57
9.13
-3.234
-2.182
-1.630
- Run with 200000 particles with the best values from the optimization code
Bunch Shape for 4.4ps and 3.3ps
100pC, pulse length = 3,3ps
100pC, pulse length = 4,4ps
40pC, pulse length = 3,3 ps
40pC, pulse length = 4,4 ps
20pC, pulse length = 3,3ps
20pC, pulse length = 4,4ps
Optimization procedure was cut after 40-50 iterations  possibly not enough to find really best values
Slice Energy Emittance and Slice Energy Spread for 4.4ps and 3.3ps
Convergency: Slice Energy Spread and Slice Emittance
Q=100pC
Pulse Shape: Gaussian t=4.4ps
Main parameters after booster at s=9.00m
N, x103
Mesh
e, mm
s,
mm
trms,mm
Erms,
keV
b, m
a
200
15x25
0.341
0.132
1.478
58.43
9.13
-1.63
392
21x35
0.326
0.129
1.482
59.12
9.05
-1.66
800
30x50
0.324
0.129
1.482
59.36
9.11
-1.66
1500
41x68
0.323
0.129
1.481
59.28
9.20
-1.71
Sensitivity Test: Solenoid
100pC, 4.4ps
Isoll
MaxB(1)
e
De, %
b
a
294.7
0.16822
0.4456
51.1
691.3
-40.86
296.5
0.16922
0.3939
33.6
419.7
-24.83
298.7
0.17047
0.3289
11.5
148.3
-9.294
299.6
0.17097
0.2989
1.36
68.81
-4.495
300.0
0.17122
0.2949
0.00
44.97
-2.873
300.4
0.17147
0.3047
3.32
32.67
-1.867
300.9
0.17172
0.3249
10.2
28.65
-1.348
301.7
0.17222
0.3873
31.3
27.04
-0.8815
303.5
0.17322
0.5518
87.1
12.25
-0.4150
304.3
0.17372
0.7524
155
11.31
-1.099
Assume Isoll(optimum)=300.0A
- The accuracy of 0.1A of the set point of the solenoid current
Should be sufficient to control the emittance
- But big difference in the optics functions…
Sensitivity Test: Bucking Coil
100pC, 4.4ps
Isoll
MaxB(2)
e
De,
%
b
a
5.6
0.00584
0.3399
7.90
100.3
-6.486
10.5
0.01084
0.3238
2.79
75.99
-5.010
16.0
0.01658
0.3150
0.00
53.71
-3.583
17.6
0.01834
0.3156
0.13
48.21
-3.211
20.1
0.02084
0.3199
1.56
41.59
-2.745
24.9
0.02584
0.3419
2.19
32.25
-2.025
29.8
0.03084
0.3818
21.2
27.12
-1.557
34.6
0.03584
0.4370
38.7
24.51
-1.269
Assume Isoll(optimum)=16.0A
Solenoid Test: Bunch Shape
Still to clear up: if the emittance increase at higher solenoid field occurs only due to the tails of the bunch…
Bucking Coil Test: Bunch Shape
Summary
• Many open questions yet…