1. Sppc injector chain design update
Yuanrong Lu
Peking University

2. Special thanks to :
Yuanrong LU, Haipeng LI, Qiuyun TAN, Xiaowen ZHU, Zhi WANG, Kun ZHU, Peking University
Xiangqi WANG, Tao LIU, Hongliang XU , NSRL, USTC
Jingyu TANG, Feng SU, Hong Yang, et al, IHEP
Linhao ZHANG, Chuanxiang TANG, Tsinghua University
And lots of colleagues from individual affiliations are not mentioned here.

3. Outline : Injector chain (for proton beam)
p-Linac: proton superconducting linac
p-RCS: proton rapid cycling synchrotron
MSS: Medium-Stage Synchrotron
SS: Super Synchrotron
Ion beams have dedicated linac (i-Linac) and RCS (i-RCS)

4. Major parameters Value Unit p-Linac MSS Energy 1.2 GeV 180
p-Linac
MSS
Energy
1.2
GeV
180
Average current
1.4 mA 20 uA
Length
~300 m
Circumference
3500
RF frequency
325/650
MHz 40
Repetition rate 50 Hz
0.5
Beam power
1.63 MW
3.67
p-RCS SS 10
2.1
TeV
0.34
Accum. protons
2.55E14
900
7200
36-40
200 25
Repetition period 30 s
3.4
Protons per bunch
2.0E11
Dipole field 8 T

5. p-Linac parameters: Parameter Value Unit Particle type H- Beam energy
1.2
GeV
Superconducting cavities for >20MeV
Beam rigidity
6.4 Tm
RF frequency
325/650
MHz
325 for <160MeV, 650 for >160MeV
Peak current 40 mA
Repetition rate 50 Hz
RF duty factor
3.4%
Chopping rate
50%
For injection to p-RCS
Average current
1.4
Half for RCS injection
Beam power
1.63 MW
Without chopping, for linac beam applications
1. 斩束率为50%
2. P-RCS为25Hz, 一半注入RCS，一半直接引出做束流

6. Many high energy p-Linac based on SNS, ADS project.
Superconducting cavity has great development.
Almost mature technology.
Key question: high acceleration gradient, chopper
Project
Energy
(GeV)
Beam power
(MW)
Duty factor
(%)
Length
(m)
Current
(mA)
SC input
(MeV)
Frequency
(MHz)
LHC
5.0
0.08…10
590 40
160
352.2
MYRRHA
0.6
2.4
100
260 4 17
176/352
ESS
2.0 5
4.0
362
62.5 90
352.21
C-ADS
1.5
150 10
3.2/2.1
325
SNS
1.0 2 6
335 65
186
402.5
超导加速器适用的能量也越来越低

7. LHC-Linac4 & SPL Linac4: room temperature accelerator
SPL (Superconducting Proton Linac)
两种超导椭球腔
R. Garobay, Geneva, “SPL AT CERN”, SRF2009

8. European Spallation Source (ESS)
Parameter
Value
Ion P
Energy (GeV)
2.0
Beam power (MW) 5
Repetition rate (Hz) 14
Beam Current (mA)
62.5
Beam pulse (ms)
2.86
Duty factor (%) 4
The input energy to the SC linac is 89.8 MeV out of DTL.
Total length (before HEBT) is about 362m
常温加速器，通过RFQ和DTL将加速到90MeV，超导部分包括spoke腔和两种椭球腔
M. Eshraqi, et al, “The ESS LINAC”, IPAC2014,
M. Eshraqi, H. Danared, et al, “ESS LINAC, DESIGN AND BEAM DYNAMICS”

9. MYRRHA—RFQ
RFQ为4杆型，176MHz, 出口能量为1.5MeV，长度达到了4m，极间电压只有40kV，功耗只有100KW。
C.Zhang, et al, “Front-end linac design and beam dynamics simulations for MYRRHA”, LINAC2012

10. MYRRHA—CH DTL
C.Zhang, et al, “Front-end linac design and beam dynamics simulations for MYRRHA”, LINAC2012

11. C-ADS
Li, Zhihui, et al. "Physics design of an accelerator for an accelerator-driven subcritical system." PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS 16.8(2013):

12. SppC p-linac RFQ, CH-DTL, Spoke cavity & elliptical cavity.
160MeV
3.0MeV
20MeV
1200MeV
RFQ
CH-DTL
Spoke
Elliptical
MEBT1
MEBT2
LEBT
Ion
325MHz
650MHz
0.05MeV
RFQ, CH-DTL, Spoke cavity & elliptical cavity.
Superconducting linac for >20MeV
RFQ, DTL and spoke cavities operate at 325MHz, elliptical cavities operate at 650MHz.
基于上面质子直线加速器的设计，给出SppC质子直线加速器的布局，
超导加速器有较大的孔径，高的加速梯度，相比常温加速器，具有很大的优势，超导加速器能量相对较低，20MeV，beta=0.20
超导spoke腔发展迅速，CH-DTL可以用低beta的spoke腔替代

13. Main RFQ parameters
Parameters
value
Frequency (MHz)
325
Input/output energy(MeV)
0.05/3.0
Beam Current(mA) 40
Transmission(%)
98.5
Vane voltage(kV) 85
Maximum surface field(MV/m)
31.97
Kilpatrick Factor
1.79
Vane Length(cm)
361.32
Synchronous Phase(deg)
-90/-25
Maximum Modulation
2.308
Average Aperture(cm)
0.278
Minimum Aperture(cm)
0.20
Input transverse x,y,norm,rms(mm-mrad)
0.250
Output transverse
x,y,norm,rms (mm-mrad)
0.232
Vane voltage keep constant at 85kV, and Kp factor is 1.79.
RFQ length is 3.6m
Four-vane
RFQ cavity power dissipation is about 440kW.

14. RFQ Dynamic Parameter Φs—— Synchronous phase B —— Focusing strength
Ws —— Synchronous energy
Φs—— Synchronous phase
m —— Modulation factor
a —— Minimum bore radius

15. Beam transmission given by ParmteqM
RFQ Simulation
Particle distribution in the transverse phase space at the entrance (top) and exit (bottom) of the RFQ
Beam transmission given by ParmteqM
Input transverse x,y,norm,rms(mm-mrad)
0.250
Output transverse x,y,norm,rms (mm-mrad)
0.232
Output longitudinal z,norm,rms (MeV-deg)
0.1106

16. Different 4-vane RFQs Project SppC C-ADS CSNS CPHS SNS LINAC4 particle
Frequency(MHz)
325
324
402.5
352.2
Win (MeV)
0.05
0.035
0.065
0.045
Wout (MeV)
3.0
3.2
2.5
Duty factor
3.4
100
1.05
6.0
0.1-10
Peak current(mA) 40 15 20 50 52
10-80
Vane voltage(kV) 85 55 80
60~130 83 78
Length(cm)
361.32
469.95
362
296.87
370
300
Transmission(%)
98.5
98.7 97
97.2
>90 95
Maximum surface field(MV/m)
31.97
(1.79Ek)
33.0
(1.85Ek)
31.68
(1.78EK)
32.0
(1.8Ek)
1.85
1.84
Cavity power dissipation(kW)
440
420
390
538
800
一些项目相似的RFQ的对比，

17. Crossbar H-Type DTL CH-Type DTL: velocity range: 𝛽=0.1-0.5
frequency: 150 ~ 700MHz.
High mechanical stability
KONUS Dynamics
High real estate gradient
Small cavity
Easily cooled
Room temperature- and superconducting operation
352 MHz,Win = 3 MeV/u
横向聚焦通过四级磁铁实现，纵向聚焦通过几个-35°相位的聚束间隙实现。
Crossbar H-Type DTL is usually the right candidate for KOUNS designs in the velocity range beat= and for resonance frequencies between 150 and 700MHz typically.
CH-cavities have an excellent mechanical rigidity due to the crossed stems and can be easily cooled. This opens the possibility of high duty cycle or superconducting multi-cell cavity applications of the CH structure.

18. KONUS Dynamics
One structure period consists of a quadrupole triplet, a rebunching section and a main acceleration section.
Main acceleration along a 0° synchronous particle structure with asynchronous beam injection and a surplus in bunch synchronous particle.
加速聚集分离作用
Main acceleration at Φs = 0°, by a multi-gap structure (1).
Transverse focusing by a quadrupole triplet or solenoid (2).
Rebunching: drift tubes at Φs = - 35 ° typically (3).

19. DTL parameter Only need about 5m. Two Coupled CH (CCH) cavity
Simulation based on LORASR code & TraceWin
Cavity power
Cavity
CCH1
CCH2
Input(MeV)
3.0
8.1
output energy
20.2
Mean beta
0.108
0.172
Length (cm)
145
315
Gap number
11+13
17+18
Acceleration gradient (MV/m)
3.50
3.84
Max field (MV/m)
13.09
17.78
𝑍 𝑒𝑓𝑓 𝑐𝑜 𝑠 2 ∅ 𝑠
(MΩ/m) 70 60
Cavity power(kW)
260
770
CH-DTL has high accelerate gradient ~5m, CSNS DTL Tank1 up to 8m
第二个腔加速梯度大，长，功耗很大

20. Beam envelope

21. Beam envelope

22. Beam envelope

23. Emittance growth(40mA)

25. FAIR
The proposed layout for the FAIR Proton injector
G. Clemente, et al, The FAIR project linac: the first linac based on a room temperature CH-DTL, HB2010

26. Coupled-CH (CCH) cavity

27. MYRRHA:
Multi-purpose hYbrid Research Reactor for High-tech Applications
1. 常温加速器为RFQ和CH-DTL，工作在176MHz，加速到17MeV，超导部分为352MHz的spoke和704MHz的椭球腔。
During the EUROTRANS project the RF frequency of the 17 MeV injector part has been set to 352MHz. The new layout is changed to 176 MHz. The main reason is the possibility to use a flexible and cheap 4-rodRFQ instead of the 4-vane-RFQ. This 176 MHz RFQ accelerates the particles to 1.5 MeV.
M.Vossberg, H.Klevin, et al, “Test RFQ for the MAX-Project”, LINAC 2012

28. SC cavity 4 sections of constant beta cavities
Spoke cavity (20~160MeV, 325MHz)
Single spoke resonator (SSR)
Double spoke resonator (DSR)
elliptical cavity(160~1200MeV, 650MHz)
5 cell/ 6 cell
𝛽=0.4 Spoke cavity
5 cell elliptical cavity

29. CM1+CM2带束调试达到项目验收指标 超导腔 成功加速10.6mA脉冲质子束至10.6MeV
CM1+CM2：每个恒温器包含7个由超导腔、超导螺线管、BPM组成的周期单元，共14个周期单元——首次、无先例可循
CM2腔在老练时达到7-10MV/m，运行在5－7MV/m
成功加速10.6mA脉冲质子束至10.6MeV
Weiming PAN

30. 6只用于25MeV的CM4正式腔性能测试达到国际先进指标
超导腔
主加速器Spoke021腔成功研制和批量制造
6只用于25MeV的CM4正式腔性能测试达到国际先进指标
Weiming PAN

31. Spoke cavity (20~160MeV, 325MHz)
Elliptical cavity(160~1200MeV, 650MHz)
The TTF versus a ratio of beam velocity β to the optimum βopt

32. SC cavity 20MeV 0.20 50MeV 0.31 160MeV 0.507 350MeV 0.685 1200MeV
SSR026
325MHz
Elliptical 062
650MHz
Elliptical 082
DSR041
20MeV
0.20
50MeV
0.31
160MeV
0.507
350MeV
0.685
1200MeV
0.899
Cavity type
frequency（MHz）
Focusing type β
No. of cavities
Energy range (MeV)
Focusing period
Cryomodules
Spoke
325
Solenoid
0.22 32
20—50 SR 8
0.42 40
50—160
SRR
Elliptical
650
Triplet
0.62 44
160—350
TR(4) 11
0.82 85
350—1200
TR(5) 17
As can be seen from the figure, a small number of cells cavity provides a large velocity acceptance. On the other hand, using a larger number of cells/cavity has the advantage of reducing the overall number of system components, system size and system complexity. As a compromise between the two, in our design, we have chosen 5 cells/cavity.
the entire energy range from 100 MeV to 1 GeV is divided into 3 sections of constant beta cavities as shown in Fig. 9.

33. Spoke Cavity Fremi SSR0 325 0.115 109.2 5.66 6.83 SSR1 0.215 242 3.84
Lab
Spoke Type
Frequency
(MHz)
𝛽 𝐺
R/Q
（Ω）
𝐸 𝑝 / 𝐸 𝑎𝑐𝑐
𝐵 𝑝 / 𝐸 𝑎𝑐𝑐
mT/(MV/m)
Fremi
SSR0
325
0.115
109.2
5.66
6.83
SSR1
0.215
242
3.84
5.81
SSR2A
0.414
247
3.78
5.64
SSR2B
0.480
304
3.5
5.9
IHEP
Single-Spoke
0.12
142
4.54
6.37
0.21
206
3.88
8.13
0.40
250
3.678
8.31
Argonne
SSR
350
251
4.0
DSR
345
3.47
TSR
0.30
492
2.77
0.63
349
2.92

34. Works under going p-RCS/i-RCS: Tang Jingyu and Zhang Linhao
MSS: a student studying lattice (with Tang Jingyu, pending)
SS: Wang Xiangqi and students

35. More about p-RCS
p-RCS will serve not only medium-stage acceleration for colliding beams at SPPC, but also other physics programs.
It is designed to work with high-duty factor
The continuous beam power from p-RCS is 3.5 MW. No other similar accelerators have been built or studied in details (FNAL is conducting a study to replace its 8-GeV Booster).
High repetition rate of 25 Hz will shorten the beam filling time in the MSS.
Only a fraction of this power is needed to fill the MSS. Thus most of the beam pulses from the p-RCS could be used for other physics programs.
p-RCS will use mature accelerator technology but be on a larger scale than existing rapid-cycling proton synchrotrons.
Examples: CSNS/RCS, J-PARC/RCS, ISIS/RCS, FNAL/Booster, NF/RCS

36. Injector chain for SPPC1
Hong YANG
Jingyu TANG
Injector chain for SPPC

37. MSS Lattice design 1.Vladimirskij and Tarasov reversed bending magnets
2.Teng π-straight sections
3.S.Y.Lee flexible momentum compaction FMC
4. Yu.Senichev “resonant” lattice

39. Pi-straight sections

40. Resonant lattice

42. Superperiods and Circumference

44. Magnets and RF
B gap=38.4mm H=51.2mm
Sagitta 11.8mm
Q r=25.6mm

46. Injection and Extraction
向MSS注入:快注入
固定靶等实验:多圈慢引出
向SS注入:单圈快引出
单圈注入：一个束团注到一个空的 RFbucket 内

47. Parameters List

49. CEPC-SPPC CCNU Symposium
Recent progress of the design study on the SS
USTC Group: Xiangqi WANG, Tao LIU, Hongliang XU
IHEP Group: Feng SU, Jingyu TANG
报告题目不好，建议改为：Recent progress of the design study on the SS
CEPC-SPPC CCNU Symposium
Apr , 2017, IHEP, Wuhan
2018/12/5

50. 2018/12/5

51. Recent progress The main design objectives, 2.1 TeV-7200 m, unchanged
Reduce working magnetic field, from T to T
Constant number of SC dipole magnets
Constant effective length of each SC dipole magnet
4804 of harmonics number
Circumference to meet longitudinal stability
88 arc FODO cell: 4 dipoles, 2 quadrupoles, 2 sextupoles
16 no-standard arc FODO cell: 4 dipoles, 2 quadrupoles
4 long straight sections used for SCRF cavities & inj. or ext.
Have filed a patent application
2018/12/5

52. Have not changed over the past year
2018/12/5

53. To meet the requirement of dynamic aperture tracking
Total length is m.
Two super period structure
Four long straight sections:
2 for injection or extraction;
2 for RF cavities and other
equipments
2018/12/5

54. Comparison of variable parameters
before 19 Apr. 2017
质子静止能量： （58）MeV。
2018/12/5

55. The new arrangement reduces the working magnetic field
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

56. To increase the transverse focusing effect
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

57. The beta function is reduced by 56.4%
2018/12/5

58. The beta function of arc region is reduced
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

59. The dispersion function at the ends of arc region
is reduced to zero
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

60. To meet the requirements of synchronization
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

61. The beta function of RF installation location
is reduced by 57.5%
The beta function of RF installation location
No change in the length of the long line segments
* Assuming the injection filling factor from MSS to SS is 80%
for inj. or ext.
2018/12/5

62. Beta function curve of RF cavity segment
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

63. No change in the length for inj. or ext.
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

64. Beta function of long straight section for inj. or ext.
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

65. Structure and Twiss function of a super period
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

66. Beam bunch structure parameters of SS
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

67. synchrotron radiation, cavity pressure & power
Energy storage,
synchrotron radiation,
cavity pressure & power
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

68. Physics performance of kickers in SS ring
* Assuming the injection filling factor from MSS to SS is 80%
2018/12/5

69. Tune-x & tune-z in the SS ring/SPPC,
2018/12/5

70. Dynamic aperture by Six Track:
mm, mm ,
2018/12/5

71. Summary
Injector chain is a very complicated and powerful accelerator system, large enough by a single stage
Work on the injection chain continues, and more volunteers (both experts and students) are needed.
Key technical challenges should be identified, so R&D program can be pursued.
Collaboration and coordination are needed.
Beam applications or physics programs of each stage will be discussed.