CEPC Accelerator Key Technology R&D status

Yunlong CHIOn behalf of CEPC accelerator R&D team, IHEP

IAS Program on High Energy Physics，HKUST

9 to 26 January 2017

Outline

• Accelerator Complex

• ACC. Key Tech.

•  R&D Program and status

• Conclutions

2

CEPC Accelerator Complex

n  CEPC consist of 10GeV Linac, 45~120GeV Booster

and 45-120GeV Main ring，

n  Accelerator Hardware Systems：

–  Beam Source

–  Linac NCRF

–  Ring SCRF

–  RF power source

–  Cryogenics

–  Magnet

–  Power supply

–  Vacuum

–  Beam Instrumentation

–  Control

–  Mechanic

–  Alignment

–  Radiation Shielding

–  etc.3

Precision@e+e-collider Energyfron3er@ppcollider

e+ e- LTB

CEPC (100km) Boostr(50Km-100km)

SppC (100Km)

Injector Linac (new base line design)

Main Ring (new base line design)

Main Ring (new base line design)

CEPC Accelerator Key technologies

n  Polarized electron gun

-  Super-lattice GaAs photocathode DC-Gun

n  High current positron source

-  bunch charge of ~3nC,

-  6Tesla Flux Concentrator peak magnetic field

n  High gradient accelerating tube

-  30Mev/m for S-band structure

-  50Mev/m for C-band structure（option）

n  High Q SC Cavity and High power coupler

-  Max operation Q0 = 2E10 @ 2 K

-  High power coupler: 300kW／650MHz

n  High efficiency Klystron

-  ~ 80% goal for 650MHz klystron

n  Large Scale Cryogenics

-  12 kW @4.5K refrigerator, Oversized, Custom-made, Site integration

7

CEPC Accelerator Key technologies

n  Low field dipole magnet

-  Lmag=4m, Bmin=31Gs, Errors <5E-4

n  IR region QD0

-  Field gradient 200T/m，magnetic length 1.46m

-  Central field 13T

n  Electro-static separator for deflect the e+ and e- bunches

-  Maximum operating field strength: 20kV/cm

-  Maximum deflection: 145 urad

n  Vacuum system

-  Dipole copper chamber

-  RF shielding bellows

-  NEG coating

etc.

8

SRF System R&D

n  CEPC Accelerator Physics and Key Technology R&D-  Supported by IHEP Science & Technology Innovation Program of

IHEP (2015-2017)

n  Task 1：Research of High Q cavity (1.82 MCNY)Ø  Study the key technologies to increase Q and gradient of SRF

cavity (N-doping, Nb3Sn, et al.)Ø  650 MHz single-cell cavity: Q0 = 2e10 @ Eacc = 15.5 MV/m for

vertical test.

N-doping Research at IHEP

N-doped cavity Q didn’t increase, possible reasons:

l  The furnace for N-doping is equipped with diffusion pump, which is

dirty. Cryopump is more clean, which is adopted by FNAL, JLAB, et al.

l  IHEP has no electro-polishing (EP) facility yet. BCP is used after N-

doping, which results in bad cavity inner surface.

Niobium samples for N-doping in the furnace

Vertical test results before and after N-doping

SRF System R&D

n  CEPC Accelerator Key Technology R&D (2016-2021)-  National Key Program for S&T Research and Development, MOST (Ministry

of Science & Technology ) (funded in 2016)

Task 2 : SRF Technology R&D（7.35 MCNY）

Ø  650 MHz 2-cell cavity: Q0 > 4E10 @ 20 MV/m

Ø  Input coupler: 300 kW CW power

Ø  HOM coupler and absorber: 1 kW and 5 kW

HOM Coupler and Absorber650 MHz cavity Input Coupler

SRF MOST R&D time schedule

2017-

n  Conceptual design of CEPC RF system; design of 650 MHz cavity, main coupler, HOM coupler and absorber.

2018-

n  Fabrication of cavity, main coupler, HOM coupler and absorber.

2019~2020-

n  Tests and improvements of cavity, main coupler, HOM coupler and absorber; design of cryomodule. Acceptance tests of cavity, main coupler, HOM coupler and absorber, which all reach the design target (Q0>4E10@20MV/m, 300kW CW power, 1kW and 5kW).

2021-

n  Technical design and review of CEPC RF system; acceptance.

SRF Infrastructures and Module Beam Test

n  Large SRF infrastructures to be built in Huairou(2017-2019)

-supported by Beijing local government.-  SRF lab and facilities: cavity processing, tuning, vertical test, module

assembly, horizontal test, defects diagnostics and repair, new material study.

-  Beam test: up to 30 mA CW beam. Demonstrate high Q, high input power and moderate HOM power handling (due to small bunch charge).

SRF Lab Layout (4500 m2)

CEPC 1.3 GHz module�

CEPC 650 MHz module�

DC photo-cathode gun�

650MHz CW Klystron R&D

n  CEPC Accelerator Physics and Key Technology R&D-  Supported by IHEP Science & Technology Innovation Program of IHEP

(2015-2017)

n  Task 2：650MH/ 300kW klystron development（3.71 MCNY）Ø  Design of high efficiency klystron (efficiency ～ 80%)；

Ø  Beam tester for klystron development；

Ø  High power test for beam tester.

650MHz CW Klystron R&D

Ajdisk: 74%

n  Mechanical design of test tuben  Coaxial window design to

manufacture and testn  Director requests us to have

more than 80% efficiency, and 2.5D simulation will be desirable using FCI, Magic and CST

n  Manufacturing infrastructure such as backing and exhausting furnace is needed

n  Longer interaction region-> Bigger furnace required

n  MBK as alternative design15

650MHz CW Klystron R&D schedule By IHEP fund：

(1)  2015.01 - 2016.11 Beam tester design

(2)  2015.06 - 2016.12 Classical klystron design

(3)  2016.12 - 2017.08 Fabrication for beam tester

(4)  2016.06 - 2017.06 High efficiency klystron design

(5)  2017.08 - 2017.10 High power test for beam tester

By other 20MCNY fund：

(6) 2017.04 - 2018.06 Fabrication and high power

test for classical klystron

(7) 2017.08 - 2018.10 Fabrication and high power

test for high efficiency klystron

16Strategytomanufacturetube�inChina�

Injector System R&D

Energy spread

Envelope

Emittance

63 Klystrons 242 Accelerating structures

Injector System R&D

n  CEPC Accelerator Key Technology R&D (2016-2021)-  National Key Program for S&T Research and Development, MOST

(Ministry of Science & Technology ) (funded in 2016)

n  Task 2: Injector（4.25MCNY）Ø  ~ 3nC for single positron bunch

Ø  Emittance of positron less than 0.3mm.mrad ；

Ø  Accelerating gradient more than 30MV/m

Ø  8 cryoplants: each cryoplant to provide cooling for one RF station;

Ø  Booster ring: 8 stations, 32 cryomodules, 4 cryomodules/each station

Ø  Collider ring: 8 stations, 80 cryomodules, 10 cryomodules/each station

The CEPC heat loads require whole plant capacity of 75.75KW @4.5K.Eight 12 kW @4.5K refrigerators will be employed. The total capacity can reach 96KW@4.5K

Cryogenic system R&D

Large scale helium refrigerator R&D

n  Technical Institute of Physics and Chemistry (IPC), CAS.

压缩机功耗 （kW）　C-100 2151.35 C-200 1290.96 C-300 0.00 CC1 0.00 CC2 0.00 CC3 0.00 Total 3442.31

制冷量（kW）　4.5K 12.676 2K 0.000

换热器　总换热量（kW） 2094.755 总UA (kJ/K.s) 687.485 液氮消耗 L/h 191

1

2 4 5 6

7 8

3

9

50KGHe

70KGHe

4K SHe

2KGHe

4-300KGHe

1 -12kW Refrigera-or flow char-

×2

×3

Large scale helium refrigerator R&D in IPC

n  IPC 10kW@20K Refrigerator

n  2~4K Refrigerator R&D

&

.5 05 7

56 2 82 8 2 8

p  D aK

yp  & 1 c

p  g ap D a C

p TD nRb

p  ht e

p  D ap  & 1 nF

p  n iIWo

p  iIr

p  r Ko n

制冷功率10.8kW

19.7K

72小时（3天）

10kW@20K低温制冷设备现场测试结果 10.8kW@19.7K，连续稳定运行3天，透平效

率≥76%

考核内容 项⺫指标

系统制冷量

超流氦系统2.5kW@4.5K

500W@2K

液氦系统 250W@4.5K

稳定运⾏考核时间 3天

关键技术透平最⾼绝热效率 75%

冷压缩机最⾼绝热效率 60%

Low field dipole magnet R&D

n  Lmag=4m, Bmin=31Gs, Bmax=614Gs

n  To verify the magnet design and field simulation, a 1m long prototype dipole magnet（booster）was developed and measured

- Supported by IHEP workshop

Low field dipole magnet R&D

Ø  The remnant field (I=0A) in the gap is about 5-6Gs.

Ø  The field quality at low field (such as 30Gs, 60Gs) is worse than the simulated results due to effect of the remnant field.

Ø  In order to reduce the effect of remnant field, the minimum field at injection energy of the CEPC booster must higher than 100Gs.

励磁效率

70.0%

80.0%

90.0%

100.0%

110.0%

0 200 400 600 800 1000

I(A)

励磁效率

磁铁前段 磁铁后段

磁铁前段横向场均匀性

-6.0E-03

-4.0E-03

-2.0E-03

0.0E+00

-30 -20 -10 0 10 20 30

X(mm)

场均匀性

50A 100A 150A 200A 520A 900A

Transverse field homogeneityExcitation efficiency

Funding requirement for Acc. R&D

n  Accelerator R&D still needs about 50M CNY more In future, ask for MOST 2018

序号 课题 研究内容 指标 经费预算（万元）

1 Interaction Region Superconducting magnets

30mrad. Central field for compensating solenoid is 13T, effective length 12.5m,angle of two apertures 30mrad

400

2 Electro static separator 62.5urad @120GeV ,=4.5m, E=20kV/cm, V=±110kV 300

3Magnet

1.  Low field dipole magnet2.  Dual-aperture dipole magnet3.  Dual-aperture quadrupole magnet4.  Dual-aperture sextupole magnet

400

4

VACUUM

1.  Dipole copper vacuum chamber2.  NEG coating3.  RF shielding bellows4.  All metal pneumatic gate valve5.  Ultra-high vacuum gauge

600

5 Injector C band structure and high power test stand 1000

6 Beam instrumentation1.  Beam position measurement2.  Beam loss monitor3.  Working point measurement

Close orbit resolution ~um，Max. count rate >10MHz，False count rate <1Hz, ensitivity>100db Noise＜120db 500

7 Power supply 1.  ±1000A/ ±500V Bipolar power converter2.  5000A/10V High-precision power converter

Ripple@0A: ≤100ppm, Tracking error:≤1000ppmStability:≤50ppm 120

8 alignment 1.  High precision alignment photogrammetry2.  Laser tracker domestication 800

9 mechanical system 1.  Dipole girder system in Main Ring2.  Dipole girder system in Booster

Accuracy≤20umAccuracy≤20um 160

10 radiation protection system

1.  120GeV/16.9mA Electron beam dump2.  1kW/m Synchrotron radiation protection 150

11 control system

1.  EPICS V42.  Machine protection 150

4580

Conclusions

n  Some R&D are under going by IHEP / MOST / other fund, such as High Q0 SRF system, High efficiency Klystron, low field magnet, large scale refrigerator etc.

n  50MCNY More fund are needed for the ACC. Key tech. R&D in future.

n  Key tech. R&D are very good people training for CEPC accelerator design and construction.

Thanks for your attention!