ERL15
簡単な発表の様子の紹介＋WG4(RF/SRF)のまとめ＋BNL見学（一部）
2015/6/15
H.Sakai
ERL15の発表資料は全部
https://indico.bnl.gov/conferenceDisplay.py?confId=909&view=standardにあります。

46pagesERL15の内容

詳しくはhttp://www.bnl.gov/erl2015/

Plenary session (1)M. Tigner ERL５０年

CERN test
facilityは900MeVで3turnの計画

Cornell/BNL
FFAG-ERLHZB: in construction

CornellはBNLと一緒にFFAGをBaseにERLを行う予定。
(細かいのは忘れた）同じビームラインにAltenating
Gradientのマグネットで周回させる。まだ検討段階。

S.Sakanaka： cERLの現状

Plenary session (2)Darasbury : ALICE 10年

cERLの発表ではこの後のWGではビームを使って色々なことを調べたいということが議論されていた。(WG2 BDのsession)
DarasburyのALICE 10年では最初の黎明期から途中でのCW crymoduleの失敗、後半のTHzなどの実験の話など。He
processもやっていたのは知らなかった。
中村さんからEUV-FELの話をした。10kWまで達成するパラメータをキチンと発表していた。質問はなかった（のが恐ろしい）が、後でASMLの人が一人来ていて、中村さんに後でずっと質問していたのが印象的だった。

N.Nakamura
EUV-FELERL2015 WG4:
RF & superconducting RF for ERL
SUMMARY
Conveners:
Hiroshi Sakai(KEK)
Erk Jensen(CERN)

2015.June.11 “WG4 SRF
Challenges in ERLs”

ERL2015 WG4: Charge
The WG4 charge is to identify the critical issues of each component in cryomodule
construction, assembly works and beam operation for ERL. Especially, we need toevaluate what is the critical issues of SRF cryomodules for high current and high charge
with low emittance beam operation. Following themes will be discussed in WG4.

•
•
•
•

Recent progress of each lab for ERL from ERL2013
Cavity & module design for ERL
Cavity fabrication & testing
HOM damping••

HOM damper and coupler development for high current
HOM calculation• RF control for stable beam operation••

RF source
LLRF control• SRF Gun
• High Q R&D

Talk break down
institute

No. of Talks

institute

No. of Talks

BNL

2

Cornell U.

2

KEK

3

Peking U.

2

HZDR

2

Virginia U.

1

FNAL

1

Colorado U.

1

IHEP

1

TU Darmstadt

1

IMP (Jlab)

1

MHI

1

Total 18 talks contribute to WG4 session !
Many thanks to the speakers !

ERL2015 WG4:WG4 Prenary session

June 8
16:20‐16:45

High‐Q R&D for SRF Challenge in
ERLS

Fumio Furuta

Cornell
University

SRF challenge for High‐Q:
 Pick up the topics of “High‐Q R&D” for SRF challenge.
 Recent High Q R&D is the hot topic for SRF field andone of the critical issues for CW operation cavities This challenging approach give the higher gradient
ERL operation.

Optimization for highest‐Q••

Fumio Furuta

High‐Q cavity challenges on Cornell ERL and SLAC LCLS‐II have been done
successfully by the optimized combinations of RBCS and Rres control.
Different surface finishes require different flux controls to minimize Rres,especially on cool down procedures.
Cornell ERLSLAC LCLS‐II

1.3GHz SRF cavity

7‐cell9‐cellHighest Qo in HT
at 16MV/m, 2K

3.5e103.2e10Estimated Pdiss/cellat 16MV/m, 2K

0.9W

0.9W

120C bake+ HF rinse

N2‐dopeSurface finish
Cool down
Trapped flux effect

Fast cool with
Slow cool with minimized
minimized longitudinal ΔT
ΔT over cavity
large verical ΔT
Not sensitive

High sensitive

9

High-Q of >3e10 at 2K in medium field is in hand now with high yield at horizontal test.

ERL2015 WG4:
WG2‐WG4 joint session
Jun. 914:00 – 15:40

Lecture Hall 2

14:00‐14:25

Investigations on Transverse Beam T. Kuerzeder
Break Up Using a RecirculatedElectron Beam

TU
Darmstadt

14:25‐14:50

HOM‐BBU Simulation for KEK ERL
light Source

S. Chen

KEK

14:50‐15:15

Linear Microbunching Gain
Estimation Including CSR, LSC And
Linac Geometric Impedances In
Recirculation Machines

C.Y. Tsai

Virginia
University

15:15‐15:40

Study of CSR impact on electron
beam in the JLab ERL

C. Hall

Colorado
University

ERL Beam dynamics and SRF
WG2 summary
 HOM‐BBU simulation
 Impedance issue to recirculating beamThanks to the WG2 contribution to discuss above themes

ERL2015 WG4:
WG1‐WG4 joint session
Jun. 915:55 – 17:35

Lecture Hall 1

15:55‐16:20

Commissioning program for the
704 MHz SRF gun at BNL

W. Xu

BNL

16:20‐16:45

Commissioning and first RF
results of the 2nd 3.5 cell SRF for
ELBE

Andre .Arnold

HZDR

16:45‐17:10

First beam characterization of
SRF gun II at ELBE with a Cu
photocathodeJ. Teichert

HZDR

17:10‐17:35

Discussion

ERL Injectors and SRF
Other WG1 summary SRF gun
 Present progress of SRF gun development
Thanks to the WG1 contribution to discuss above themes

Commissioning program of the 704 MHz SRF gun at BNL
Wencan Xu

 Building up:
1. Mid. 2010: vertical cavity test in Jlab, reached 2.9 MV w/o cathode stalk.
2. Mid 2011: 500 kW CW fundamental power coupler conditioning.
3. 2011 to 2013: Installation of the whole cryostat; Preparation/commissioning thesubsystems: cryo, LLRF, vac, instrumentation, cathode preparation system…
 Commissioning:
1.
Nov. 2012 to Mar. 2013: Commissioned SRF gun cavity w/o cathode stalk
inserted.
Demonstrated the SRF gun to be able to operate at 2.0 MV CW.
The amplitude stability is 2.3e‐4 rms and the phase stability is 0.035 deg rms.
2.
Aug. to Oct. 2013: Commissioned SRF gun cavity with copper cathode stalk
inserted.
Found operational parameters: 1.85 MV, 180 ms, 1 Hz ‐ limited bymultipacting in the stalk.
Design a new multipacting‐free cathode stalk with Ta tip for high QE => highcurrent electron beam.
3.
May 28 to Jun. 18, 2014: Commissioning with Cs3Sb photocathode and darkcurrent was observed.
 Understood the reasons for no photoemission beam and resolved the issues; Demonstrated that the SRF cavity’s performance was not degraded byNb cavity
photocathode insertion.
4.
Nov. 17, 2014 : First photoemission beam commissioning
 Observed photoemission beam, measured beam parameters and cathode’s
QE.
5.
March to April, 2014: Multipacting free cathode stalk Demonstrate the multipacting‐free cathode stalk is “Truly Mulitpacting‐free”.
6.
June 1 to present, 2015: High charge beam commissioning with new cathodestalk.
 0.55 nC per laser pulse

3rd gapnd
2 gap
1st gap

First observed beam on Beam profile monitor

Wencan Xu

Beam

RF offRF on

Parameters: Laser: 6.08 Watt; RF: 1.2 MV, 500 ms;
 Beam: bunch charge: 7.7 pC, photoemission current 1 μA, dark current:38 nA;
Focusing the beam with RT solenoid.

13

ERL workshop June 7‐12 2015

2nd
ELBE
SRF
gun
cavity
2nd
ELBE
SRF
gun
cavity& SRF test results (1)Andre Arnold(HZDR)••

still challenging to built and prepare extraordinary SRF gun cavities, 4 years for 1 cavity !
coldmass- + cryomodule assembly and cooldown at the ELBE LINAC done within 6 month !

•low power RF tests• external Q of FPC = 9.3e6 corresponds to BW = 140 Hz @ 1.3 GHz• tuner resolution = 0.3 Hz/step, total tuning range = ±272 kHz, no hysteresis• relatively high pressure sensitivity = 155 Hz/mbar but not critical•high power RF tests• moderate microphonics, closed loop phase noise = 0.02° and amplitude stability = 1e-4
• 6x higher Lorentz force detuning than TESLA 9 cell cavities(caused only by half cell, critical for our small bandwidth)
André Arnold

11

300

10

SRF-Gun No2 - 3rd horizontal meas. (05/08/2015)
SRF-Gun No2 - first horizontal meas. (08/13/2014)
SRF-Gun No2 - last vertical test result (09/19/2013)
SRF-Gun No1 - last horizontal result (02/15/2013)
30 W limit
10

250

200

10

Darkcurrent [nA]intrinsic quality factor, Q0

ELBE
SRF
gun
cavity2nd2ndELBE
SRF
gun
cavity& SRF test results (2)QvsE•

30% loss due to FE compared
to last vertical test•

Tremendous loss after Cs2Te
cathode transfer due to particle
contamination of the cavity•

But still better than SRF gun I

150

9

10

Ecath
 1.53Eacc

100

E peak

50

Eacc

8

 2.56

0

10

0,0

2,0M

4,0M

6,0M

8,0M

10,0M

accelerating gradient, Eacc [V/m]12,0M

Andre Arnold(HZDR)

Investigation of FE source•

Analysing of spatial γ‐ray
distribution points to half cell•

QvsE for all 4 TM010 passband
modes point to 1st or 2nd iris•

Comparison of simulated andmeasured dark current spectra
points to first iris as FE source

14,0M

1st Contamination risk of SRF gun cavities by NC cathodes is not yet eliminated !!
2nd More effort (money) in fabrication needed to increase yield of usable cavities !!
André Arnold

ERL2015 WG4: WG4‐session 1 & 2Jun. 10

10:45 – 12:25 & 14:00 – 15:40

Lecture Hall 2

Overview of the progress after ERL13 andreview of the cavity and cryomodule test:
Cavity design & test and fabrication for ERL: Laboratory talks
 Cavity design for high current & its performance Module design for ERL & its performance Operation experiment of cryomoudle
 Cavity design for high current ERLs & its performance Cavity fabrication for mass production
 Cavity design for kicker cavity
 SCRF related development
 HOM damper and coupler development
 Input coupler development

ERL2015 WG4: WG4‐session 1 & 2Jun. 10

10:45 – 12:25 & 14:00 – 15:40

Lecture Hall 2

10:45‐11:10

Cornell's ERL main linac cryomodule:
design, construction and results

Ralf Eichhorn

Cornell
University

11:10‐11:35

Operational experience of CW SRF
Injector and Main linac cryomodules at
the Compact ERL

Hiroshi Sakai

KEK

11:35‐12:00

The development of the high current
superconducting cavity at IHEP

Zhenchao Liu

IHEP

12:00‐12:25

Recent Progress in SRF Acceleration
Technology at Peking University

Senlin Huang

PekingUniversity

14:00‐14:25

SRF cavities for high current ERLs

Wencan Xu

BNL

14:25‐14:50

Development for mass production ofsuperconducting cavity by MHI

Kohei Kanaoka

Mitsubishi
Heavy
Industries(MHI)

14:50‐15:15

Harmonic Resonant Kicker Design for
the MEIC Electron Circular Cooler Ring

Yulu Huang

IMP (Jlab)

15:15‐15:40

Discussion

Finishing the MLC @Cornell

SC magnets & BPMs

1.8 K

7-cell cavity

Ralf Eichhorn (Cornell U.)

Beamline HOM absorberIntermodule unit

nominal length: 9.8 m

Prototype of a Linac Cryomodule
for the Cornell ERL:•

six packages of 7-cellcavity/Coupler/tuner•

five regular HOMs/
two taper HOMs

ERL7‐006
ERL7‐007
ERL7‐002a

High-Q of all cavities.were achieved in V.T.

Target Frequency
Frequency as Built
(MHz)
(MHz)
1298.85 1298.486
1298.75 1298.386
1299

1298.578

TargetLength(mm)1157.84
1157.391161.66

Length as Length Post‐
ΔLengthBuilt (mm) Tune (mm)1157.85
1157.99

1159.091159.30.09
0.3

1161.361160.08

0.08

Ralf Eichhorn (Cornell U.)

Cornell HOM Beamline Absorbers
HTC-2: No HOM Absorbers
HTC-3: With HOM Absorbers

More than 40mA with 2.7ps was achieved to suppress HOM with HOM damper !

Hiroshi Sakai

OPERATIONAL EXPERIENCE OF CW SRF INJECTOR AND MAIN
LINAC CRYOMODULES AT THE COMPACT ERL (cERL)
Compact ERL Layout

Main linac module
HOM damped (for 100mA circulation
to suppress HOM-BBU in design)
9-cell cavity (ERL-model2)× 2

20MeV
Recirculation(return) loop

RF frequency: 1.3 GHz
Input power : 20kW CW (SW)

Dump
Main-linac

Eacc:

15 MV/m（design）

Unloaded-Q:

Q0 > 11010

CryostatTwo 9-cell SC cavities

MergerInjector-linac
Photocathod
e DC gun

3MeV

Injector module
2-cell cavity × 3
Double coupler

2-cell Cavity

HOM
absorber

Tuner

Target of cERL
Current : 10-100mA
Energy : 35MeV
 Change 20MeV
due to field emission
Input couplerseRequirement was satisfied at V.T. Heavy F.E
was met @9-10MV/m after string assembly.

Tuner

Cryostat*) Progress from ERL2013

RF frequency: 1.3 GHz
Input power :Start beam operation with ERL return loop.

10kW/coupler (10mA, 5MeV)
180kW/coupler (100mA, 10MeV)
Eacc:

Input Coupler

7.6MV/m（5MeV）
15MV/m (10MeV)

Unloaded-Q:

Q0 > 11010

e-

HOM Coupler &RF FeedthroughRequirement was satisfied at V.T and for initial 10mA requirement .

••Completed construction in Dec. 2013.
Commissioned started in Dec. 2013.
20MeV 10uA (Dec.2013 – Jun.2014)
20MeV 100uA (Jan.2015 – Jun.2015)

Q‐value history of Main linac (ML)(from high power test to beam operation for 2.5 years)

High power test

High power test

Hiroshi Sakai

Beam operation

Beam operation

ML1

•
•
•
•

ML2

We kept stable beam operation by digital LLR Fsystem (A/A < 0.01% , < 0.01 deg) andsuppressed the microphonics.
Several trips were observed on a year. No crucial hardware trouble ,for example, come from missoperation of CW beam & or quench was met by fast & sophisticated ITL system to beam and RF.
We met the Q degradation & radiation increase during beam operation on ML. We apply pulse
processing pragmatically. Now we keep stopping cavity degradation. (ML1:200mSv/h, ML2 80mSv/h)
We plan to make the new cryomodule with four 9cell cavities to overcome field emission problem.

Zhenchao Liu

Slotted High Current Cavity
HOMs’ Damping Comparison
Why not open the damping structure on the cell!
F (GHz, withcovers)1.524
1.5312
1.5926
1.5979
1.677
1.68
1.713
1.75261.74921.794
1.8405
1.9
1.973
2.052
2.086
2.184
2.1985
2.254
2.324
2.365
2.4
2.437

Measured ValueQL (with covers, still
QL (≈Qe, without
have field leak)covers)
560
x
714
x
624
x
606
100
1037
x
995
x
94
x
1192
x
1280
x
1312
x
2047
344
445
x
714
x
470
x
615
x
531
172
321
x
1450
x
1990
2136
1224
x
1071
630
800
667

F (GHz, without
covers)
x
x
x
1.599
x
x
x
x
x
x
1.842
x
x
x
x
2.173
x
x
2.324
x
2.4
2.437

Calculated Value
Qe (without
F (GHz)covers)
5.2
1.525
2.17
1.599(TE111)
5.74
1.676
20.4/8.8
1.754/1.747
446
1.855(TM110)
15.9
1.973
5.43
2.043
15.2
2.093
14.2
2.175
20.7
2.252
1859612.326 *
105.1
2.439 *

*Notes on TABLE III: Many HOMs disappeared in the network analyzer when opening the waveguide port as the QL of these mode decreased below
10 or so. These modes are depicted by “x”. Since there are several calculated modes around the measured frequency or the frequency shift between
June 24,2015 and calculated frequency is large, we use “-” to depict. * depicts quadruple mode.
22
measuredfrequency

Zhenchao Liu

Conclusion• A 1.3 GHz 3‐cell slotted cavity
prototype has been fabricated.
• The cavity was processed at thestandard procedure for SC cavity at
IHEP.
• Room temperature RF test shows
the slotted cavity has very highdamping on HOMs.
• 4.2K vertical test was carried out
and the cavity show great
potential on ERL application• 2K vertical test will be done soon

June 24, 2015

Zhenchao Liu

23

DC‐SRF Photoinjector is in Stable Operation @PKU

Senlin Huang

Stable operation of DC-SRF photoinjector has been achieved since 2014.

E-beam energy: 2.8-4 MeV
Bunch charge: 5-50 pC
Bunch rep. rate: 0.1625-81.25
MHz
Macro pulse length: 1 ms -CW
Norm. trans. emittance: ~2 µm▲ Beam profile▲ EmittanceThe beam has been used to generate THz
superrandiant undulator radiation. ▼Beam line
06/10/2015

ERL2015, Stony Brook, NY

24

Senlin Huang

25 MeV Straight Section is Under Construction

Assembling of 2x9-cell cryomodule will be done before the end of this summer.
Beam loading experiments will be carried out this year.

3 MeV e-beam
8~25 MeV e-beam;
Bunch charge: 20~50 pC;
Bunch length, rms: <0.5 ~ 5 ps
▼The cryomodule in position▼Existing large-grain
cavities▼ Cavity tuners readyRF couplers tested ▲06/10/2015

ERL2015, Stony Brook, NY

25

High current cavities at BNL Wencan Xu

 HOM is the main concern for high current ERL machines, which includes HOM-induced
transversal and longitudinal BBU and HOM power. The cavity optimization should address theseeffects.
 There are 3 high current cavities at BNL: a 704 MHz BNL1 cavity for R&D ERL, a 704 MHz
BNL3 cavity for conventional lattice ERL eRHIC and CEC POP project (the cryomodule willcommissioning during next RHIC run), and a 422 MHz BNL4 cavity for FFAG lattice ERL eRHIC (a3-cell prototype cavity will be made and its performance will be study).
Parameters

BNL 1

BNL 3

BNL3_scale

BNL 4Frequency [MHZ]704

703.87

422

422.2

beta

1

1

1

1

Cells No.

5

5

5

5

Geometry Factor

225

283

283

273

(R/Q)/cell [Ω/cell]

80.8

101

101

100.6

Epeak/Eacc

1.97

2.46

2.46

2.27

Bpeak/Eacc [mT/MV/m]

5.78

4.26

4.26

4.42

Coupling factor [%]

3.00

3.02

3.02

2.83

Length with HOM damper(cm)
Beam pipe radius (mm)Radius after tapered (mm)First HOM frequency (MHz)272

160 (eRHIC)

267

256

120
N/A

110
50

183
83
483

180
80
498

26

HOM damping

Wencan Xu

HOM damping for the whole HOM spectrum is a challenge for high current ERLs.
Damping 7.8 kW per cavity is required for full luminosity eRHIC and two types(coaxial-line and waveguide) of HOM damper will be used.
HOM damping scheme will be tested with the prototype cavity at 2K.

 6 coaxial-line HOM couplers on the cavity for
low frequency HOMs: ~ 5.6 kW
 3 rectangular waveguide HOM damper on thebeamline taper for high frequency (>5 GHz, so
the waveguide is small) HOMs: ~2.2 kW
 Preliminary results show encouraging
performance of this damping scheme

27

Kohei Kanaoka

Summary (MHI’s work for KEK cERL)
KEK cERL

Two cryomoudule made by MHI works well

■Injector Module （2-cell cavity×3）

Electron gun■Main Accelerator Module （9-cell cavity×2）■SRF electron gun （For the future）
STEP1; Design of the shape of the cavity

STEP3; Study of Prototype#2
・Choke structure
・Coupling calculation of Input coupleretc.
© 2015 MITSUBISHI HEAVY
INDUSTRIES, LTD. All Rights Reserved.

28

STEP2; Prototype#1

Choke structureKohei Kanaoka

Summary (MHI’s developing activities for mass‐production etc.)■Laser Beam Welding for the stiffener ling

■Reducing the number of parts Unification of parts■EBW Four 9-cell cavities in one batch■RRR measurement of Cu electroplating sample
For High power input coupler⇒High electric conductivity⇒ Low thermal conductivity

100
80
60
40
20
0

RRR

without HT■Seamless dumbbell

Spinning© 2015 MITSUBISHI HEAVY INDUSTRIES,
LTD. All Rights Reserved.

Reference;
H.Sakai,
TTC2014@DESY

29

after HT

0

10

20

Cu plating thicness[μm]3040Ultra-Fast Harmonic Resonant Kicker Designfor the MEIC Electron Circular Cooler Ring
MEIC Future High
Luminosity Upgrades

Yulu Huang

Yulu Huang

Need High Current(~1.5A)Electrons circulate 25 Turns in circulator ring , thus thecurrent in the source and linac can be reduced by a factor 25.
Cooling section
ion bunchelectronbunchsolenoid

1.5A, 55MeV, 476.3MHz•••

Fast kicker

circulator ring

Gun/booster

SRF Linac

Periodically kick 1 inevery25 bunches
Ultra-fast ,2.1 ns
55kV(1 mrad kick angle)

Fast kicker

dump

0.06A, 55MeV, 19.052MHz(476.3/25)
30(bunch repetition frequency)

4 Cavities with 10 Harmonic Modes to Kick
Every 10th bunch in a 476MHz bunch train
14

QWR

Mode
(MHz)

12
10
8

5 harmonics
47.63MHz1,3,5,7,9

6
4
2

47.63
95.26
142.89190.52238.1510285.78MODES
333.413 harmonics
381.0447.63MHz2,6,10
428.67
476.3
DC
Total
1 harmonics 47.63MHz4
0

2
4
6
8

10
12
14

0

0. 5

1

1. 5

2

2. 5

3

0

3. 5

4

4. 5

5

5. 5

s

6

2

60
50
40
30
20
10
0

0

1

2

3

4

5

6

FFT Kick
Voltage(kV)
13.711
12.462
10.5328.12905.50302.91700.6300-1.2090-2.4320-3.01108.276055.5081 harmonics 47.63MHz8

Yulu Huang

CST Trans.
DissipateShunt
d Power
Impedance (Ω)(W)
7.13E626.37
1.14E7
13.62
4.09E627.12
1.35E7
4.89
3.14E69.64
6.09E6
1.40
2.65E60.15
1.65E70.09
2.40E6
2.46
4.57E6
1.98
3.56E787.72

Two to Three ordersof magnitude lower
than a strip-line
kicker31

••Discussion in WG4 session 1 & 2What is the present status for high current ERL of each components?
– Cavity design & test results are OK to meet the more than 100mA operation
 Need to be cared not to contaminate the field emission source in storing assembly.
– HOM damper/coupler limit at present ?
 HOM damper works well with CW 40mA at Cornell? Waveguide is also candidate.
– How much power can be fed by one FPC. (> CW 100mA)
 Cornell 50kW/coupler, KEK 40kW/coupler 1.3GHz, BNL 500kW/coupler 700MHz
What is the optimum & stable CW operation field with High‐Q for a long time ?
– 15‐20MV/m and Q0=(1‐3)*10^10 desired (LCLS‐II: 2.7*10^10@16MV/m with N2‐dop) Push high‐Q study more.
– How long high‐Q will be kept and how much degradation ratio and stoped?
 CEBAF 1‐2%/year, SNS also meet the degradation ??/year.
 KEK met degradation during beam operation. But it seems to be stopped now.
– How to stop the field emission (Dark) current from cavity in operation ?
 By using collimator and Q‐magnet between the cryomodules.
 We need careful simulation and discuss with beam dynamics Group (WG2).
– What is the performance translation from the V.T to H.T ?
 V.T to cryomodule with Q0=2*10^10 (Cornell), EURO‐XFEL 20% degradation)

ERL2015 WG4:WG3‐WG4 joint session
Jun. 10

15:55 – 17:35

Lecture Hall 2

15:55‐16:20

Performance of the digital LLRF
systems for cERL at KEK

Feng Qiu

KEK

16:20‐16:45

Resonance Control for Narrow‐
Bandwidth, Superconducting
Accelerator Applications

J. P. Holzbauer

FNAL

16:45‐17:10

Using a 1.3GHz 20kW Solid State
Amplifier as RF Power Supply for
DC‐SRF Photo‐injector

Fang Wang

PekingUniversity

17:10‐17:35

Discussion

ERL Instrument and SRF
 LLRF control and its stability performance for ERL
 RF sources for ERL Tuner performance and control for ERL
Thanks to the WG3 contribution to discuss above themesRF systems in cERL
LLRF cabinet

RF sourcePre. Amp.

RF = 1300 MHz

SW1

FPGA

I_Set

Clk ≈ 80 MHz
LTC2208
ADC

PI

IIR

PI

Q

Calib.

ADCADC

AMC Card

Fi l
Fi l

IF ≈ 10 MHz

ADC

Vector sum Fil.
I
IIR

 cos sin sin cos 

0.1 % rms, 0.1 deg. rms for cERL
0.01% rms, 0.01deg.rms for 3GeV-ERL

1300 MHz

Kly. / SSA

IQ Mod.

Down
Convertor

Analog filter

bandwi dth

Monitor(pick up)

Q_Set

μTCA board

RF requirement

Schematic of LLRF
LO ≈ 1310 MHz

F.Qiu

Performance of LLRF

DIO (RF SW)
I_FF
 cos sin sin cos 



Q_FF

Calib.

DAC I
DAC

Q

AD9783

Power PCLinuxEPICS IOC
Waveform

CommandBeam Momentum jitter is 0.006% (in agreement)This LLRF almost satisfied RF requirement of not only cERL but also 3GeV-ERL

Adaptive FF approach
Adaptive FF also
works well.

FF  s 

Set

PI ( s )  KP KIs

PS ripples

Basic idea of Adaptive FF
control (model-based)

I: HVPS ripples

Micr ophonics

Beam-loading

PS Ripple + Beam
DAC
FF

d

CavityCav
GP  s F.Qiu

Microphonics

III: MicrophonicMicr ophonics
PS Ripple + Beam
DAC
FF

d

Cav
GP  s removing dˆ

dˆ

Inv.
GP1  s App. I: PS ripples rejection

Disturbancesof cERL
LLRF system
App. II: Beam-loading
compensation

II:Beam-loading

App. III: Microphonics rejection

35

Best Results at FNAL••

New control system seems
to have removed the
double-peak seen in the2011 FNAL data.
Measurement conditions:
•
•
•
•
•
•
•
•
•
•
•
•
•

36

J.P. Holzbauer

Open loop drive
4.3 K
0.25 Hz Bandwidth
5.8 Peak/RMS
325 MHz Single Spoke Resonator
2 hours of data
Fast feedback loop
Slow feedback loop
LFD feedforward
11 mHz RMS detuning
14 MV/m Gradient
1.3 degrees RMS phase
0.02% RMS amplitude

J.P. Holzbauer | Resonance Control for Narrow-Bandwidth, SRF Applications

6/6/2015

J.P. Holzbauer

Conclusions•

Controlling cavity detuning will be critical for successful operation of PIP-II
because of narrow cavity bandwidths (f1/2~ 30 Hz)– Narrow bandwidths would be challenging even with CW operation alone– Pulsed mode operation brings significant additional complications•

All possible passive measures must be exploited but active control will still be
required– Will require both best LFD and best microphonics compensation achieved
to date operating reliably over many cavities and many years• Early test results provide reason for CAUTIOUS optimism– There are no existing examples of large machines that require active control
of detuning during routine operation– Cross-disciplinary challenges may be more difficult to solve than technicalchallenges (which are still considerable)

37•

Minimizing cavity detuning requires optimization of entire machine•Will require active coordination across divisions and across disciplines

Warren Schappert | P2MAC_2015

3/10/2015

Fang Wang

Applications 1.3GHz CW Amplifiers
Facility

Type

Power

DC-SRF Injector at
PKU

SSA

1×20 kW from BBEF

ELBE at Rossendorf

SSA

4×20 kW from Brucker

bERLinpro cavity

SSA

3×15 kW (?)

Cornell
ERL injector

Klystron

5×120 kW from e2v

Cornell
ERL injector

IOT

1×16 kW from Thales

ALICE at Daresbury
Lab

IOT

5 IOTs from three manufactories(e2v 16kW, CPI 30kW, Thales 16kW)

ERL 2015

IHIP, Peking University, China

38

Summary of 1.3GHz 20kW CW SSA @PKU

Fang WangA 1.3 GHz 20 kW CW solid state amplifier is developed under thecooperation between BBEF (Beijing) and Peking University. It is the first CW
solid state amplifier more than 10kW in China.
Test results shows the technical specifications are mostly achieved.
— RF average power 20 kW— 3dB bandwidth ＞± 30 MHz— Gain ＞85 dB— RF phase shift vs. output 9。5°
— Gain change vs. output 1.6 dB— 2nd harmonic -69 dB— 3th harmonic -56 dB— Temperature gradient of power ±0.8% / °C
— Delay 75ns
— Efficiency 34% at 20 kW output, 20% at 9.5 kW output

It has been applied to the experiments of the DC-SRF photo-injector at
Peking University since 2012 and works stably.
— Amplitude Instability <0.1%— Phase Instability <0.1°
ERL 2015

IHIP, Peking University, China

39

Discussion in WG3‐WG4 joint session• LLRF satisfy the our requirements ?
– LLRF works well. Encouraging results.

• Strategy to reach the high current beam > 100mA– We need to consider the process to commission the ERL.
– We need to start the beam tuning with nominal bunch charge.

• Even in an CW ERL, transients must be considered.
– Failure modes (not only stop the injector but also eject beam)– Clearing gap– …

• Hit worse HOM’s of one cavity– Detuning– De‐Qing– Feedback ?

Summary A positive and steady advance is seen at every laboratories.
– Accumulation of operation experience, improvement of existing machine, construction
and new proposal of ERL.

 Progress of the development of components:– Recent high-Q R&D is a great work especially with N2 doping (FNAL Cornell) . This lead
us to reach more higher gradient CW operation of ERL– Cavity performance including cryomodule test has reached to the ERL level and meetrequirements. (Cornell)– We met the degradation with field emission (FE) during the long beam operation (KEK).
– HOM damper was performed with real high current beam with CW 40mA (Cornell).
– Calculated BBU current > 100 mA with BBU suppressed cavity design (BNL, Cornell,
KEK, HZB) and new design with slotted type was suggested. (IHEP)– Cavity fabrication technique catch up with the mass production phase now. (MHI)– LLRF with tuner control of stable power source reach very high stability. (A/A < 0.01% , < 0.01 deg) (KEK, FNAL, PKU)
– New SRF guns start in operation (HZDR,BNL). Dark current is severe problem at present.

 As the next;– All key components are in the level of practical use expect for HOM damper (>100mA).
– However we know the difficulty of SCRF operation with high gradient in cw mode,
because of FE and other disturbances.
– Construction of new ERLs is underway (ex. HZB,Cornell/BNL,CERN). We will accumulate
the operation experiences so that we can meet for stable operation at the next ERL2017.

Thank you

BNL tour (ERL test facility) (1)BNL tour (ERL test facility) (2)一応、loopが全部できていた。主にinjector部がメインでcomissioning
ここで縦
測定を行
っている。

NSLS‐II (1)NSLS‐II (2)James Roseさん

500MHz (CESR type)が1つすでにNSLS-IIにinstallされている。写真はもう一つの500MHzの空洞(AES)が横スタンドに置かれている状態。
(150kWまでがmax:windowの問題)
黄色の空洞（サブマリンをimage(^-^))はあらたに1.5GHzの３倍波の超伝導空洞。これらは自分らで作ってassembyも自分らのclean roomで組んでいる。今後横測定をする予定。