1. Beam dynamics of RAON accelerator system
20th May 2013
Eun-San Kim
KNU
(Kyungpook National Univ.)

2. Contents  Beam dynamics in - FRONT-END ( LEBT, RFQ, MEBT )
- LINAC ( Linac-1, Charge stripper, Linac-2, HEBT)
 Beam dynamics in
- Post accelerator ( Linac-2, Charge stripper)
- P2DT
- Linac-2

3. LEBT EQ BM PS Length :15.872m HV 1 DG D G 2 3 4 2.69 m ρ=0.65m 3.42 m
Slit D G 3
deflector VE
RFQ PS
ECRIS EQ
Sol 1 DG
Col 2
2.69 m
3.42 m
7.42 m 4
Length :15.872m BM
ρ=0.65m
Chop : Chopper
DG1 : Slit,View,WS,FC
DG2 : EM,FC
DG3 : Slit,View,WS,FC
DG4 : WS
PS : pair solenoid
EQ : Electrostatic Quadrupole (Triplet)
Col : collimation system
MHB : Multi Harmonic Buncher
VE : Velocity Equalizer

4. LEBT 1m 16m PS BM1 SLIT Chop DG2 BUN SOL VE RFQ BM2 DG1 COL D G 3 EQ
Verti
6cm
4cm
2cm 1m
Hori
2cm
16m
4cm
6cm PS
BM1
SLIT
Chop
DG2
BUN
SOL VE
RFQ
BM2
DG1
COL D G 3 EQ
DG4 E C R

5. LEBT (1 M particle tracking)
■ Energy : 10 keV/u 238Uranium Q : 33+,34+ ■ Emittance(n,r) : 0.08 π mm mrad ■ ΔE/E ~1.5%
Exit ECR
Between two bends

6. LEBT (1 M particle tracking)
Downstream MHB
Upstream VE
Entrance of RFQ

7. LEBT components Element Amount Strength Length [cm] Bending Magnet 2
Θ = 90 ˚
Pair Solenoid 4
5.0 kG
30, 30
Solenoid 1
6.0 kG 50
ESQ 3
10.0 kV
15 ,15 ,15
10.0kV
15,15
MHB
MHz .
MHz .
MHz . 24
Velocity Equalizer
MHz 10
Chopper
3 kV 15

8. 238U+33 238U+34 RFQ (using 1 M particles from LEBT) 10 keV/u 500keV/u
81.25 MHz, 70kV124kV
238U+33
238U+34

9. (using 1 M particles from LEBT)
RFQ
(using 1 M particles from LEBT)
Exit of RFQ
■238U+33
■238U+34
Phamteq
TRACK
TRACK

10.                                                                                                                                                                                                                                                                                                                                  
MEBT
Exit of MEBT
Exit of RFQ

11. Charge stripper section
ORBIT

12. Charge stripper section Magnet parameter in CS line
　Charge state
Population [%]
Charge state
74+
0.43
80+
20.80
75+
1.53
81+
12.77
76+
4.41
82+
5.17
77+
11.24
83+
1.32
78+
18.78
84+
0.203
79+
23.33
Slit
Slit
Magnet parameter in CS line
Rc, Gap [mm]
Leff [mm]
Btip, Bgap [T]
Max B' [T/m]
# of element
Remark* Q1 25
250
0.53
21.2 4 Q2 60
300
0.6 10 8
Bend 50
1257
1.3　 1 Q3
100
0.65
6.5
Q4A Q4
0.35 14
Q4B

13. Linac Layout

14. Linac1+CS+Linac2 (U beam from LEBT)

15. Linac1+CS+Linac2 (1 M particles from LEBT)

16. Linac1+CS+Linac2 (1 M particles from LEBT)
εnx: mm-mrad
εny: mm-mrad
εnx: mm-mrad
εny: mm-mrad
εnz: 5.51 keV/u-ns
εnz: keV/u-ns

17. Linac1+CS+Linac2 (1 M particles from LEBT)

18. Linac1+CS+Linac2 (1 M particles from LEBT)

19. HEBT (Optics)
J. Yoon

20. HEBT (1 M particles from LEBT)

21. HEBT (1 M particles from LEBT)

22. Proton beam (Initial Beam condition)
■ Energy :
■ Qdesign : Adesign : 1
■ Emittance(n,r) : 0.15 π mm mrad
Emittance(n,full) : 0.9 π mm mrad
■ ECR extraction hall size : 5 mm
■ ΔE/E ~0.05%

23. Proton beam (LEBT) -60 ˚ < 84.5% < 60˚ 1D dE/E (%)
4*ezn : keV/u ns
1D dE/E (%)
event
1D phase (degree)
-60 ˚ < 84.5% < 60˚
event

24. Proton beam
(RFQ)

25. Proton beam
(MEBT)
Exit of RFQ
Exit of MEBT
envelope

26. Proton beam (Charge stripper section)

27. Proton beam (Linac+CS+Linac2)
Beam parameters
E0 = MeV/u for 1p
σx = 1.31 mm, εnx = mm-mrad
σy = 1.43 mm, εny = mm-mrad
σz = deg MHz)
εnz = 1.10 keV/u-ns

28. Proton beam (Linac1+CS+Linac2)

29. Start-to-End Simulation (U-beam)
Number
of Particle
Transm.
Efficiency
(%)
Current[puA]
33+, 34+
Nor.rms εx
[mm-mrad]
Nor. rms εy
Nor. rms εz
[MeV-deg]
Initial
100
6/6
0.075 -
LEBT
998000
99.8
0.082
3.56
RFQ
976562
97.6
5.92/5.7
0.11
0.13
1.81
MEBT
0.112
0.135
1.84
SCL1
972430
97.2
0.124
0.146
3.92 CS
822143
82.2
0.148
0.193
25.69
SCL2
813787
81.3
1.12/1.97/2.56
2.42/1.57 (9.8)
0.15
0.2
39.05
HEBT
1.12/1.97/2.56/2.42/1.57 (9.6)
0.195
0.229
165
FRIB

30. Start-to-End Simulation (proton)
Number
of Particle
Transm.
Efficiency
(%)
Current[mA]
Nor.rms εx
[mm-mrad]
Nor. rms εy
Nor. rms εz
[MeV-deg]
Initial
10000
100 1
0.15 -
LEBT
0.005
RFQ
8784
87.8
0.87
0.175
0.174
0.019
MEBT
0.197
0.207
0.021
SCL1
8783
0.218
0.241
0.024 CS
0.233
0.250
SCL2
0.236
0.259
0.032

31. SCL3+P2DT+SCL2 (132Sn beam)

32. Linac 3 [132Sn20 , TRACE_WIN]

33. Linac 3 [132Sn20 , TRACE_WIN]

34. P2DT (132Sn beam)

35. SCL3+P2DT+SCL2 (132Sn beam)

36. SCL3+P2DT+SCL2 (132Sn beam)

37. SCL3+P2DT+SCL2 (132Sn beam) Beam parameters
E0 = MeV/u for 132Sn45+
σx = 2.44 mm, εnx = mm-mrad
σy = 2.46 mm, εny = mm-mrad
σz = deg MHz)
εnz = 1.62 keV/u-ns

38. Used simulation codes LEBT : TRACK, IMAPCT, TRANSPORT
RFQ : TRACK, PARMTEQ
MEBT : TRACK, IMAPCT, TRACE3D
LINAC : TRACK, IMPACT, TRACE_WIN
P2DT : TRACK, TRACE3D
HEBT : TRACK, IMPACT, GCOSY

40. Errors in Linac Initial energy : 500 keV/u
Beam current : 0.2 mA for each charge state
Macro-particle : 1k particles for each charge state
# of seed : 116
Misalignment error
QMs : 150 um [Uniform]
BMs : 150 um [Uniform]
Cavities : 500 um [Uniform]
Tilt error
All elements : 5 mrad
Cavities Voltage & Phase error : 1 % [Gaussian]

41. Orbits in Linac-1
Before correction
Before correction
After correction

42. Scheme for orbit correction [QWR]
Two cell was merged to one for correction.
1cell
Corrector
BPMs
Beam
~75.5 cm
15cm
16cm
74cm
QWR Beam-line specification
Strength of QMs : ~ T (effective length : 16 cm)
Effective length of QWRs : 22 cm , Peak E field : 15 ~ 30 MV/m
Initial energy : 0.5 MeV/u, Final energy : 2.57 MeV/u, # of cell : 22
BPMs and Correctors are installed in each QMs.

43. Scheme for orbit correction [HWR]
Two cell was merged to one for correction.
20cm
~14.5 cm
1.40 m
HWR1 cell
19 cm
~25cm
20cm
~14.5 cm
1.40 m
19 cm
~25cm
Corrector
BPMs
20cm
16.5 cm
2.72 m
HWR2 cell
19 cm
25 cm
20cm
16.5 cm
2.72 m
19 cm
25 cm
Corrector
BPMs
HWR Beam-line specification
Strength of QMs : ~ T (effective length : 20 cm)
Effective length of HWRs : 25 cm , Peak E field : 21 ~ 30 MV/m
Initial energy : 2.57 MeV/u, Final energy : 18.6 MeV/u , # of cell : 13 (HWR1), 14 (HWR2)
BPMs and Correctors are installed in each QMs.

44. Summary
Start-to-end beam simulations were performed to optimize the beam and accelerator parameters for multi-charge state beams.
- The simulation results show that our design is within scope of our goals.
More things to do
- Longitudinal emittance needs to be reduced more.
- Error effects

45. LEBT Initial Beam condition
■ Energy : 10keV/u Uranium ■ Q_design : 33,34 A_design : 238 ■ Emittance(n,r) : 0.07/0.08 π mm mrad (U33,34) ■ ECR extraction hall size : 5 mm ■ ΔE/E ~1.5% (Q : 33.5)

46. LEBT (Longitudinal distribution @ RFQ entrance)

47. U33.5+
IMPACT-Z result
U33.5+
TRACK result

48. LEBT Electrostatic deflectors- - - - - - - - E + + + + + + + + + d l
Extraction voltage L
d = 5.25 cm → beam size should become
smaller than collimator

49. Multi harmonic buncherrf
Voltage ratio for a three freq.
MHz = 1
MHz = 0.351
MHz= 0.115
diameter of electrode : 4 cm
CST code simulation

50. LEBT Velocity Equalizer system
■ Reduce the effective energy spread of
two-charge state beams
Shape of VE E-field
e : elementary charge
V0 : accelerating voltage
A : mass number
m0 : nucleon rest mass
q0 : highest charge state of ions
c : speed of light
10keV/u in 238U34+, 238U33+
Δp/p = 0.75%
RFQ_Frequency : MHz
V0 : 71.04kV
A : 238
m0 : 938.5
q0 : 34
MHB to RFQ
→ L = 1.12 m

51. LEBT (Proton) Element Amount Strength Length [cm] Bending Magnet 2
Θ = 90 ˚
Pair Solenoid 4
1.0 kG
30, 30
Solenoid 1 50
ESQ(Triplet) 3
2.0 kV
15 ,15 ,15
ESQ(doublet)
1.0kV
15,15
MHB
MHz .
MHz .
MHz . 24
Velocity Equalizer
MHz 10
Chopper
1 kV 15
□ Magnet strength for proton beam transport is weaker (~ 1/7) than Uranium’s

52. LEBT
Pair solenoid
FEMM code simulation

53. LEBT
Solenoid
FEMM code simulation

54. Charge stripper section
(collimator)
Collimators to prevent the damage on cryomodule
Liquid Li
Carbon stripper
SCL1
Charge stripping section with matching section
Horizontal and vertical width of collimator
X [cm]
Y [cm]
1st slit
0.6
2nd slit
0.8
3rd slit
0.5
1.0
4th slit
0.7
5th slit
Collimation rate in each collimator in CS line
Loss particle 77 78 79 80 81 % kW
2nd slit
0.145
0.005
0.01
0.06
0.05
0.02
3rd slit
0.195
0.025
0.04
0.065
4th slit
0.105
0.03
0.015
5th slit
0.13
0.035

55. Charge stripper section Energy straggling : 0.011 % rms
(solid carbon)
2. SRIM calculation (straggling)
Stripper
Solid carbon
ΔE (MeV/u)
0.14
E FWHM (MeV/u)
Angle (mrad)
0.19
Angle FWHM (mrad)
0.45
SRIM
0.3 mg/cm2 (carbon foil)
Energy loss : 0.14 MeV/u
Energy straggling : % rms
Angular straggling : 0.19 mrad

56. Charge stripper section
(solid carbon)
The simulation of the stripping efficiency and straggling are required to estimate the effect of the solid carbon stripper.
Charge stripping rate estimation
→ LISE ++
0.3 mg/cm2 (carbon foil)