Accelerator/RFQ

Alain FRANCEfor the ESS RFQ Team at CEA Saclay

www.europeanspallationsource.seApril 21, 2015

RFQ Overview

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RFQ realized in 5 sections (L = 0.92 m); total length = 4.58 mCuC2 copper and stainless flanges38 vacuum ports (24 in S1-S2-S4-S4) 60 adjustable slug tuners (34 in S1-S2-S3-S4-S5), 80 mm dia.8 end-tuning rods (4 per end plate)8 10mm-diameter cooling channels per section (variable length)2 power coupling loops (S3)20 pickups for voltage profile reconstruction

Deliverables tuned and conditionned RFQ on its support RF distribution system water cooling skid

Planning January 2016 - start RFQ machining October 2017 - start RFQ tuning July 2018 - ready at ESS

Schedule

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RFQ Technical performances

Frequency nominal 352.21 MHz, controllable over ±100 kHz with Df3dB/10 resolution during operation Df3dB over 10 sec agility Df3dB/10 stability during pulse 10 Df3dB separation of other modes

Power dissipated 1.6 MW max with 70 mA beam current 4% duty cycle reflection coefficient < 15 dB at nominal beam current RF couplers sustend Inf SWR Voltage voltage profile satisfying beam dynamics requirements 1.9 Kp max E-field quadrupole component error < 1% (TBC with beam dynamics analysis) dipole components < 1% (TBC with beam dynamics analysis) 2 pick-ups min for LLRF (+20 for voltage profile monitoring)

L3 System Requirements and L4 RFQ EMR System Requirements, Dec 19, 2014 Ed.

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RFQ Technical performances

Vacuum pressure < 5 10-7 mbar over 75% of RFQ length Geometry vane tip surface tolerance < 20 mm transverse vane displacement < 30 mm wrt theoretical vane position transverse vane tilt < 30 mm over 1 m transverse section displacement < 30 mm wrt theoretical beam axis transverse section tilt < 30 mm over 1 mTemperature warm-up < 30 minutes avoid corrosion + water cooling system requirements under transfer from ESS to CEA

Status of design studies RF design of cavity completed; design of RF distribution in progress thermal-mechanical design of cavity during operation completed mechanical design (supporting, transport, handling, ...) in progress water cooling skid design in progress (interfaces)

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RFQ Selected technologies

Deliverables tuned and conditionned RFQ on its support, RF distribution system, water cooling skidRF design four-vane structure, naturally stable single segment tunable devices: end rods, vacuum ports, slug tunersFabrication of RFQ modules 4 electrodes with modulations and apertures for ancillaries one step of copper-copper brazing in vertical position (IPHI) 5 modules with length < 1 m in agreement with demonstrated technologyBrazed vacuum ports avoid machining of grids in the vanes accurately positioned after electromagnetic measurements, prior to braze (Linac4)RF couplers loops offer less power dissipation and voltage ripple (Spiral2) small coaxial window standard tuner port allows coupling adjustment at final QAdjustable slug tuners performances achieved at last tuning step are saved under vacuum allow for last minute corrections, after transport for instance no delay required for machining after last tuning step

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RFQ Selected technologies

RF distribution one magic Tee, one power load and two feeders loops in opposite quadrants to minimize voltage perturbation phasing trombone to minimize reflection coefficient Voltage profile monitoring 5 4 pick-ups will allow reconstruction of voltage profile check RFQ voltage integrity vs. time voltage profile corrections are possible to some extentWater cooling dedicated skid with four independent circuits independent control of frequency and voltage function eventually useful for voltage corrections

(superseded view with hybrid)

RFQ Integration and Verification

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RF power loop validation by manufacturing followed by conditionning with a new RF source at CEA ESS RFQ loops separately conditionned: RFQ conditionning expected to be shorter Adjustable slug tuners performances achieved at last tuning step are saved Carlo Rossi Review: "The proposed use of adjustable tuners is an interesting option to assure the possibility to tune the accelerating

field after transport and installation in the ESS tunnel; in the case of Linac4, after transport into the tunnel, it has been calculated that a change of the tuner penetration of few tenth of mm would be required to re-establish an accelerating field within the specified range. It would be worth investigating the impact of such solution on the long-term reliability of the system, once a detailed design has been developed."

Validation of tuners and vacuum ports assembly process

A cavity with 2 RF power loops + 1 vacuum port + 1 adjustable slug tuner

RFQ Organization at partner lab

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RFQ Budget and cost-book

Activity ID Activity name

11.3.3.1 Management 86411.3.3.2 RFQ Complementary Engineering Studies 63311.3.3.3 RFQ Copper Procurement 20011.3.3.4 RFQ Prototyping 37711.3.3.5 RFQ Construction (with RFQ conditionning) 6,636

Total 8,710

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RFQ Major Procurements

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Call for tender - summer 2015

Start manufacturing - beginning of 2016

Assembly on support - 2nd part of 2017

Conditionning and test with beam - 1st part of 2018

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RFQ Top risks

Schedule CDR remark: “On the other end the schedule shows that three months could be sufficient for the complete fabrication of one segment, which

appears as a very optimistic estimate; the fabrication of segments appears in the schedule as a serial process, while in reality it should be possible to organize the construction such that some fabrication stages can progress in parallel. This aspect is a key point in the discussion with the companies that will participate to the tender, as well as the required logistics, which may have a considerable impact on cost and schedule.”

start rapidly copper part manufacturing and define the equally important industrial process, machining process and

brazing process

Interfaces We need to have more validated information about interfaces with building (floor and electrical power), utilities (RF

and vacuum), linac (LEBT and MEBT)

will be run in parallel

Next Six Months

Call for tender for RFQ manufacturing

Copper delivery

Copper treatment by HIP technic

Coupler test bench manufacturing

CDR2 to clarify interfaces to finalize the RFQ support design (handling and installation)

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RFQ Summary

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design activities (RF distribution, supporting, handling, water cooling) going on

intensive exchange of interface informations

realization technologies identified, supported by prototype cavity

call for tender in summer 2015 for final delivery mid-2018