This material is based upon w ork supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan

State University. Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

Ting XuOn Behalf of FRIB Project Team

Completion of FRIB Superconducting Linacand Phased Beam Commissioning

MOOFAV10

T. Xu, SRF2021 28 June 2021, Slide 2

▪ Introduction

▪Completion of Superconducting Linac

▪Phased Linac commissioning

▪ Looking forward: Linac upgrade

▪Summary

Outline

T. Xu, SRF2021 28 June 2021, Slide 3

Facility for Rare Isotope BeamsA DOE Office of Science User Facility

▪ Funded by DOE–SC Office of Nuclear

Physics with contributions and cost share

from Michigan State University

▪ Accelerate ion species up to 238U with

energies of ≥ 200 MeV/u and beam power up

to 400 kW for rare isotope production

▪ Fast, stopped, and reaccelerated beam

capabilities

▪ First user experiments expected in 2022

Future Upgrades

▪ Capable of energy upgrade to >400

MeV/u by filling vacant slots with ~ 11

cryomodules

▪ Possibility for Isotope Separation On-line

(ISOL) to allow multi-user simultaneous

operation with light and heavy ions via

addition of a light-ion injector

FRIB Driver Linac Technical Construction Completed46 Cryomodules, 4 SC Dipoles, 242 RT Magnets, 7 RT Bunchers, 1 RFQ

RFQ

LS3 Cryomodules LS1 Cryomodules LS2 Cryomodules

FS2 SC Dipoles Beam Delivery System Folding Segment 1

Cryo-distribution

▪ System utilities in place Jun 2017

▪ Last equipment (Li Stripper) installed Mar 2021

T. Xu, SRF2021 28 June 2021, Slide 5

▪ 4 cavity types, 6 cryomodule types: designed, developed, fabricated, and tested at MSU with industrial suppliers.

▪A dedicated full SRF processing and cryogenic testing facility was built 2014 to support in-house SRF production.

▪ Total of 6 years of production to deliver all cryomodules for FRIB linac.• Jan 2015: received first production cavity (β =

0.53 HWR) from vendor

• Production completed May 2020 after Covid-19 pandemic shutdown.

▪ Last cryomodule installed in tunnel July 2020. Last segment (LS3) cooled down Nov 2020, energized Feb 2021.

SRF Production Completed: May 2020

Last cryomodule (SCM518) transported to FRIB tunnel 23 Jun 2020

T. Xu, SRF2021 28 June 2021, Slide 6

21

SRF Production Summary and Statistics

Cavity Processing Summary

Cavities Processed 343

Cavity Tests 410

Reprocess Rate 22%

Cavities Certified 337

▪ A total of 49 cryomodules were produced, including one for

NSCL ReAccelerator.

▪ Peak production rate was 3 cold masses and 1.5 cryomodules

per month.

▪ Developed unique FRIB “bottom-up” cryomodule assembly

sequence; demonstrated scalable production model with less

floor space needed. Cold mass assembly and cryomodule

assembly are in different buildings.

▪ Major Reworks▪ One β = 0.085 QWR cryomodule (SCM805): beam line vacuum vent due to tuner

bellows failure. Reworked all cavities.

▪ One β = 0.53 HWR cryomodule (SCM511): one cavity weld failed during cool

down in bunker test. Replaced cavity in clean room.

Average time on assembly floor is 110 days

East High Bay: cryomodule assembly

SRF High Bay: cavity processing,

clean room

assembly, and

cryomodule testing

Bottom up design: single station for the entire

assembly

T. Xu, SRF2021 28 June 2021, Slide 7

FRIB Linac CommissioningPhased Beam Commissioning in Parallel with Installation

LS1

LS3BDS FS2

123

5

LS2FS1 4

6

▪ We planned 7 beam commissioning stages with an Accelerator Readiness Review (ARR01-07) preceding each stage. ARR01-05: through Linac. ARR06-07: through target and secondary beam line.

ARR01 (Jul 2017)

Through RFQ and MEBT40Ar9+, 86Kr17+; 500 keV/u [1]

ARR02 (May 2018)

Through LS1 β=0.041 cryomodules40Ar9+, 86Kr17+; 2 MeV/u [1]

First SRF acceleration

ARR03 (Feb 2019)

Through LS1 and FS1 (all

QWRs)40Ar9+, 20Ne6+, 86Kr17+,

129Xe26+; 20.3 MeV/u [2]

ARR04 (Mar 2020)

Through LS2 (all QWRs, 168 HWRs)36Ar18+; 204.4 MeV/u KPP Reached

129Xe49+, 50+, 51+; 180 MeV: multi-

charge-state Acceleration [3]

ARR05 (Apr 2021)Though FS2, LS3 (all cavities); Li Stripper,

rotating carbon stripper86Kr34+; 212 MeV/u; 238U37+; 20 MeV/u

through Li Stripper to FS1

[1] LINAC2018-WE2A01

[2] SRF2019-MOFAA3[3] Phys. Rev. Lett. 126, 114801

T. Xu, SRF2021 28 June 2021, Slide 8

Lithium Stripper Commissioned with Beam:World’s First Beam Stripping with Lithium

Lithium charge

stripper station

Carbon charge

stripper station

▪ Lithium stripper is one of the key elements for FRIB high power beam

▪Design allows physical coexistence of lithium stripper and carbon stripper for enhanced availability

▪Commissioned April 2021 with beam in FRIB tunnel• 124Xe26+ at 17 MeV and 238U37+ at

20 MeV through LS1 and Li stripper to FS1 beam dumps.

• High power beam tested successfully: 36Ar10+ at 400 W, duty cycle = 5.4%

Deflector

Image through viewport

Nozzle

Li Film

Beam Spot

Before Li stripper: green

After Li stripper: orange,

blue

Beam current

124Xe

Rotating carbon foil stripper installed

and tested under vacuum at 20 rpm

with beam

T. Xu, SRF2021 28 June 2021, Slide 9

▪Cavity performance tracked: cavity test (VTA); cryomodule test (bunker); linac tunnel. No Q0 degradation observed.

Cryomodule Performance In Linac

Bunker tests: Q0 was measured by dP/dt

of He-II; benchmarked with heater

VTA Q0 measurement

example: β = 0.29 HWRs

Tunnel: dynamic load was obtained with

heater power to compensate RF off with

constant 2 K flow

310 W Cavity on

590 W Cavity off

Constant LS2 mass flow

Bunker tests indicate 302 W dynamic load for LS2

LS2 total dynamic heat load based on compensation heater is 280 W

Cav ity Heater

He II Bath P

▪ Cavity field measured from RF and from

beam are generally in good agreement.

BPM signal has higher noise to signal ratio

toward end of LS2.

Design goal: LS2 dynamic load ≤1 kW at 2 K

T. Xu, SRF2021 28 June 2021, Slide 10

▪ All cavities: initial turn on, conditioning, and resonance control development done at 4 K.

▪ Linac cryomodule bath pressure oscillation is dominated by slow cycle (of order 1 hour), which is easily compensated by tuners. High frequency oscillation is small for both 2 K and 4 K operation.

▪ Resonance control: well within amplitude and phased requirements without fast tuning.

▪ Amplitude/phase control is comparable at 2 K and4 K due to stable linac pressure.

Linac: Stable Operation at 2 K and 4 K

Pressure variation using of two of LS2 cryomodules as examples

LS1 085QWR

LS2 29HWR

LS2 53HWR

LS3 53HWR

LS1 041QWR

T. Xu, SRF2021 28 June 2021, Slide 11

▪ Field emission of the cavities has been tracked and monitored.

▪ Two X-ray sensors are permanently installed under each cryomodule (total 92) in the linac for commissioning and monitoring during operation.

▪ In tunnel: conservative admin limit for X-rays (~10 mR/hr) for most cavities to avoid deconditioning. A few cavities are kept below design field to reduce X-ray levels.

▪ Pulsed RF conditioning has improved a few cavities. In-situ plasma processing development has been initiated and is in the early stages.

Field Emission Monitoring

WEPTEV011 Development of In-Situ Plasma Cleaning for the FRIB SRF Linac

X-rays in Dewar, bunker, tunnel

QWR plasma cleaning

study

▪ ARR05 beam commissioning was done during COVID-19

Pandemic: 5 control rooms for social distancing.

▪ Commissioning in parallel with technical construction: daily

turn on/off of all cavities and magnets needed.

▪ Applications were developed to facilitate commissioning and operation of SRF cavities and SC solenoids.

High Level Applications for SRF Commissioning and Operation

MOPTEV010 RF System Experience for FRIB Half Wave Resonators

THPFAV004 Solenoid Automatic Turn-On and Degaussing for FRIB Cryomodules

5 Control Rooms

Cavity Auto

Turn-on

Linac Auto-off

Automatic Multipacting

Conditioning

Nonlinear Pneumatic

Tuner Control

Solenoid Auto Turn-on

Degauss

T. Xu, SRF2021 28 June 2021, Slide 12

HWR Operational ExperienceFirst Linac to Deploy a Large Numbers of HWRs

▪ Linac commissioning confirmed that FRIB design goals for Q0, Eacc,

and bandwidth were reasonable. Higher gradient operation will be

challenging and require more resonance control development.

▪ MultiPacting (MP) of FRIB HWRs is relative easy to condition (1-2

hours), but requires careful handling to avoid deconditioning.

▪ DC bias (-1 kV) is used to suppress MP in the FPCs. FPCs were

high-power conditioned by vendor or/and FRIB before installation.

▪ Pneumatic tuners operate smoothly. Tight control of cavity frequency

allows tuners to operate between 18 and 70 psia. Tuner gas

distribution system is integrated with cryogenic gas management

system. Running above atmospheric pressure allows tuner gas

return through magnet lead flow gas return in a closed loop (total flow

about ~1 g/min) and minimize contamination to helium system.

T. Xu, SRF2021 28 June 2021, Slide 13

HWR module Tuner valve panel

External Fast

ProtectionBeamline CCG,

FPC CCG,

Spark Detector,

Bias Voltage Analog

External Slow

ProtectionHelium Level, Pressure,

FPC temperature (DO),

FPC CCG (DO),

Cooling water

▪ Three-level interlock

scheme used to protect

cavity, FPC, and amplifier,

which provides good

protection and flexibility of

commissioning.

LLRF Configurable

ProtectionCavity Field,

FWD and RFL power,

Tuner pressure

SRF R&D for FRIB Energy Upgrade: FRIB400Prototype Cavity Performance Meets FRIB Upgrade Goal

T. Xu, SRF2021 28 June 2021, Slide 14

▪Design choices▪ 644 MHz βopt = 0.65 elliptical cavity, 5-cell

▪ 55 cavities in 11 cryomodules will double the beam energy to 400 MeV/u in existing tunnel.

▪ SRF R&D▪ Two prototype cavities have been built and tested.➢ Achieved the design goal (Q0 > 2e10 at Eacc =

17.5 MV/m) with standard EP

➢ Achieved Q0 = 3.5e10 at 17.5 MV/m with N-doping

➢ In collaboration with ANL (EP) and FNAL (N-doping)

WEPTEV006 Progress in FRIB Energy Upgrade Cavity R&D at Michigan State University

TUPCAV007 First Nitrogen-Doping Results in Medium-Beta 5-Cell Elliptical Superconducting Radio Frequency Cavity for Hadron Linacs

▪ On-going R&D tasks➢ Preservation of performance in jacketed cavity

➢ Prototype cryomodule design

➢ Technical verification of subsystems in a (prototype)

cryomodule: resonance control stability against microphonics

with FPC, flux trapping in a cryomodule ("real" environment)➢ High Q0 R&D using single-cell cavities

Summary

T. Xu, SRF2021 28 June 2021, Slide 15

▪FRIB driver Linac system installation is complete: 46 cryomodules with 324 cavities.

▪After 5 stages of commissioning, FRIB successfully commissioned beam through the entire SRF linac to the Beam Delivery System (BDS) dump and demonstrated 200 MeV/u (Key Performance Parameter of the project).

▪Key features have been demonstrated, including multi-charge acceleration and lithium stripping.

▪FRIB is currently installing equipment in the target area and fragment separator area the final commissioning stages. Project is on-track to be complete by Jan 2022 (early completion date).

We Cannot Build FRIB Alone and Are Leveraging Expertise Worldwide

T. Xu, SRF2021 28 June 2021, Slide 16

Co-authors

▪ T. Xu, Y. Al-Mahmound, J. Asciutto, H. Ao, B. Bird, B. Bullock, N.K. Bultman, J.

Bonofiglio, F. Casagrande, Y. Choi, C. Compton, W. Chang, J. Curtin, K.D. Davidson,

K. Elliott, V. Ganni, A. Ganshyn, J. Gao, P. Gibson, W. Hartung, N. Hasan, Y. Hao, L.

Hodges, K. Holland, J. Hulbert, T. Kanemura, S. Kim, M. Ikegami, P. Knudsen, Z. Li,

S.M. Lidia, G. Machicoane, C. Magsig, P. Manwiller, F. Marti, T. Maruta, K. McGee, E. Metzgar, S.J. Miller, D. Morris, H. Nguyen, P.N. Ostroumov, A. Plastun, J.T.

Popielarski, L. Popielarski, X. Rao, M. Reaume, K. Saito, M. Shuptar, B. Tousignant,

A. Taylor, A. Stolz, H. Ren, A. Victory, D.R. Victory, J. Wei, E. Wellman, Jeff

Wenstrom, John Wenstrom, Y. Yamazaki, C. Zhang, Q. Zhao, S. Zhao, FRIB,

Michigan State University, East Lansing, Michigan, USA.▪ A. Facco, INFN/LNL, Legnaro (PD), Italy

▪ K. Hosoyama, KEK, Ibaraki, Japan

▪ M.P. Kelly, ANL, Argonne, Illinois, USA

▪ R.E. Laxdal, TRIUMF, Vancouver, Canada

▪ M. Wiseman, JLab, Newport News, Virginia, USA

T. Xu, SRF2021 28 June 2021, Slide 17

▪ Presented work supported by the U.S. Department of Energy Office of Science DE-S0000661

Thank you

T. Xu, SRF2021 28 June 2021, Slide 18

WEPFDV004 A New Model for Q-slope in SRF Cavities: RF heating at Multiple Josephson Junctions at Weakly Linked Grain Boundaries or Dislocations

WEPTEV011 Development of In-Situ Plasma Cleaning for the FRIB SRF Linac

WEPTEV006 Progress in FRIB Energy Upgrade Cavity R&D at Michigan State University

TUPCAV007 First Nitrogen-Doping Results in Medium-Beta 5-Cell Elliptical Superconducting Radio Frequency Cavity for Hadron Linacs

TUPFAV005 Installation and Commissioning of the ReA6 Superconducting Linac

More info in poster sessions• Preparations in target area and

secondary beam line for ARR06-07.

A1900 fragment separator

Vertical fragment separator

Target Hall MOPTEV010 RF System Experience for FRIB Half Wave Resonators

THPFAV004 Solenoid Automatic Turn-On and Degaussing for FRIB Cryomodules