Injector and Main Linac Fumio Furuta, Peter Quigley Cornell - - PowerPoint PPT Presentation

ff97@cornell.edu, pgq1@cornell.edu 1/30 CBETA Review, 27 July 2016

Injector and Main Linac

Fumio Furuta, Peter Quigley Cornell University

ff97@cornell.edu, pgq1@cornell.edu 2/30 CBETA Review, 27 July 2016

Outline

• Introduction
• Injector status
• Main Linac status
• Next steps

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6 MeV +/- 36 MeV 42, 78, 114, 150 MeV

Injector Cyomodule (ICM):

• High beam loading
• Small QL∼ 5･10 4 to 4･10 5
• Large bandwidth Δf∼ 2 to 13 kHz

Main Linac Cyomodule (MLC):

• No (almost) beam loading
• High QL∼ 6･10 7
• Small bandwidth Δf∼ 10 Hz

Field stability requirements:

• σA/A ∼ 1･10 -3
• σΦ ∼ 1 deg
• Field stability requirements:
• σA/A ∼ 1･10 -4
• σΦ ∼ 0.15 deg

Introduction

ff97@cornell.edu, pgq1@cornell.edu 4/30 CBETA Review, 27 July 2016 http://www.classe.cornell.edu/Research/SRF/SrfNews2010.html

Injector Cryomodule

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ICM and parameters

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Intrinsic quality factor Q vs. accelerating field Eacc of the injector SRF cavities at 1.8K after rework of the cryomodule.

ICM past performances in L0E

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Time required to reach 50 kW Processing history

Pulse processing (1.5 msec, 50 Hz) of new couplers installed in the injector cryomodule

Coupler Pulse Processing ICM past performances in L0E

ff97@cornell.edu, pgq1@cornell.edu 8/30 CBETA Review, 27 July 2016

• Injector Cryomodule (ICM):
• Installed in L0E.
• Completed 4K cooldown on 06/09/2016.
• Performed 2K pump-down for system check on

06/15/2016. Returned to 4K operation.

• Currently operating at 4K.
• LLRF connections in progress.

ICM status

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ICM in L0E

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• Injector Cryomodule (ICM):
• Helium vessel to insulation vacuum leak:
• This leak has existed since 2009 L0 installation.

Installed active pumping turbo and successfully

• perated ICM without issue.
• For the L0E ICM installation, vacuum vessel is

actively pumped with two 150 L/s turbo pumps and activated charcoal bags mounted in vacuum vessel.

• At room temperature:
• Base Pressure: 1e-5 torr.
• Leak rate: ~6e-5 torr-liter/sec.
• At 4K operation:
• Base pressure: 4e-7 torr.

ICM status

ff97@cornell.edu, pgq1@cornell.edu 11/30 CBETA Review, 27 July 2016

• Klystrons:
• Installed on L0E Mezzanine
• All power, water, instrumentation, LLRF connected.
• RF waveguide 98% installed. Final component

installation in progress.

• Initial RF power testing is tentatively scheduled to start

the week of 08/01.

ICM status

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120kW Klystrons in L0E

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After turn RF on ,,,

• LLRF system check.
• Coupler conditioning.
• Measure Q vs E.
• HOM calibration.
• Check HP helium gas cooling (needs operating couplers

at high forward power).

• coordinate with gun staff and others to get 1 mA through

the injector to the dump.

Injector, Next steps

ff97@cornell.edu, pgq1@cornell.edu 14/30 CBETA Review, 27 July 2016 Image; moving MLC to Wilson lab, Mar2015.

Main Linac Cryomodule

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Un-stiffened Cavity Stiffened Cavity

7-cell cavities and MLC parameters

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Three layers of magnetic shielding:

• Vacuum Vessel

(carbon steel)

• 80/40 K magnetic shield

enclosing the cold mass

• 2 K magnetic shield enclosing individual cavities

Magnetic shielding

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Cavity string and Rad monitor notes

Cavity#1 Cavity#5 Cavity#2 Cavity#3 Cavity#4 Cavity#6

the chimney on 2K2P line to HGRP

MLC Cooling schematic

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• Cavity RF test
• Tuner test
• HOM scan
• Microphonics meas.

MLC test

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2 4 6 8 10 12 14 16 1 2 3 4 5 6 Eacc max [MV/m] cavity#

Quench Admin. Admin. Admin. Admin. Limit.

*FE processed out.

FE

• 5 of 6 cavities had achieved MLC design gradient of 16.2MV/m at 1.8K in MLC.

Test results of Max fields at 1.8K

MLC cavity RF test

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1.00E+09 1.00E+10 2 4 6 Qo at 16.2MV/m cavity# *Q0 at 16.2MV/m with severe FE. *Q0 after many quench. *Q0 after FE processed out. 1.8K

• 4 of 6 cavities had achieved design Q0 of 2.0E+10 at 1.8K.

*Q0 at 14MV/m, FE started.

Target Qo 2.0e10 at 1.8K

MLC cavity Q0 at 16.2MV/m, 1.8K

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Rate; ~36K/min. dTvertical; ~36K near Tc Rate; ~0.13K/h dTvertical; ~0.6K near Tc

Top bottom dTvertical dTvertical

• Plot shows the temp. profiles on

top and bottom of Helium tank.

• To pass through the Tc
• Fast cool down w/ large dT ;

~10min. for 6 cavities.

• Slow cool down w/ small dT ;

~20hrs for 6 cavities.

Thermal cycles on MLC

ff97@cornell.edu, pgq1@cornell.edu 22/30 CBETA Review, 27 July 2016

5 10 15 20 Eacc [MV/m]

MLC cavity #5

1E+10 5 10 15 20 Q0 Eacc [MV/m]

MLC cavity #1

5 10 15 20 Eacc [MV/m]

MLC cavity #2

5 10 15 20 Eacc [MV/m]

MLC cavity #3

1E+10 5 10 15 20 Q0 Eacc [MV/m]

MLC cavity #4

FE processed out 1.00E+09 1.00E+10 5 10 15 20 Q0 Eacc [MV/m]

MLC cavity #6

Qo after RF processing Quench limit, FE free

Thermal cycle with small temp. gradient over cavity improved Qo.

Impact of thermal cycling

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Tune has been done on all six cavities in 1.8K, successfully.

MLC tuner test

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Dipole HOMs on MLC were strongly damped below Q~104. Consistent with HTC and simulation results.

HOM scan analysis

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• Preliminary results of mechanical vibration peaks on MLC.
• stiffened and un-stiffened cavities had similar peak.

Microphonics meas. (1)

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Initial measurements showed,

• Stiffened cavities had ~30Hz detuning, Un-stiffened cavities had ~150Hz

detuning (ERL design ~20Hz, CBETA 50~100Hz).

• MLC had no optimization against detuning when these data were taken.

Microphonics meas. (2)

ff97@cornell.edu, pgq1@cornell.edu 27/30 CBETA Review, 27 July 2016

• the vibration peak of ~60Hz seemed to make high gain on detuning on un-stiffened

cavities.

• Identification of vibration source, vibration-elimination or isolation are needed.

Microphonics meas. (3)

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Identify and isolate the vibration sources

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• Cooling down to 1.8 K again, re-instate running conditions.
• Run LLRF and analyse free run data.
• Analyse pressure sensor data (1.8 K system)
• Take more accelerometer data.
• Add pneumatic dampers

to pump-skids and other vibrations generators.

• Measure HOM spectra of the

remaining cavities.

Main Linac, Next steps

ff97@cornell.edu, pgq1@cornell.edu 30/30 CBETA Review, 27 July 2016

• Injector and Main Linac are commissioned, tested, and

ready for CBETA.

• Some optimization remains for the MLC.
• Injector cryomodule will be turned RF on next week, the

week of Aug. 1st. LLRF system check, coupler conditioning, Qo meas., and HOM meas. are planed.

• Main Linac Cryomodule is maintained at 4K currently,

waiting cool down to 1.8K again. more optimizations for LLRF and microphonics are planed.

Summary