International Workshop on Linear Colliders

2010

Design and fabrication update on PSI/Trieste X-band phase-

space rotator structure

Dmitry Gudkov 21-OCT-2010 WG 4 «Main Linac and NC RF»

Contents

2

Aim of Engineering Design

Engineering Design Overview

Mechanical Design of Copper Disks and Couplers

Accelerating Structure Assembly Sequence

Cooling System

Wake field monitor Feedthrough

Tuning System

Fabrication strategy

3

73 Cells

2 Couplers

2 Regions for monitoring wakefields

Aim of Engineering Design

The aim of engineering design of the structure is to transfer the RF geometry into real hardware device which can be produced with existing technological methods of metal working and assembly.

The European FEL projects FERMI@ELETTRA and PSI-XFEL plan to employ an X-band structure to compensate nonlinearities in the longitudinal phase space in order to improve bunch compression.

* RF-design done by R. Zennaro, M. Dehler and colleagues from PSI

Engineering Design Overview

4

- The accelerating structure consists of two coupler subassemblies, 73 disks and includes a wakefield monitor and diagnostic waveguides;- The engineering study includes the external cooling system, consisting of two parallel cooling circuits;- RF tuning system, which allows phase advance tuning of the cell by deforming the outer wall;- The engineering solution for the installation and sealing of the wake field monitor feed-through devices that are integrated in the accelerating structure are presented.

5

Mechanical Design of Copper Disks and Couplers

- The accelerating structure body consists of a stack of thick cylindrical copper disks, which are machined following the RF design of the cavity geometry.- For the final RF frequency tuning, the disks are equipped with four radial holes. - Each special wakefield monitor disk incorporates four coupling holes and is also equipped with tuning holes.

Wakefield monitor waveguide

Radial tuning holes

Hole for feedthrough installation

Mechanical Design of Copper Disks and Couplers

6

Cell shape accuracy 0.004 mm Flatness accuracy 0.002 mm Cell shape roughness Ra 0.025

Standard Disk

Mechanical Design of Copper Disks and Couplers

7

WFM Disk Type 1

WFM Disk Type 2

WFM Disk Type 3

WFM Disk Type 4

WFM Disk Type 5

WFM Disk Type 6

Interface Disk (Brazing)

Coupler Body

Accelerating Structure Assembly Sequence

8

1. Bonding of 3 stacks containing 24..25 disks each-Each stack includes one disks with slots for the next operation of brazing. -Slots are used for insertion of brazing alloy

PHOTO: S. LEBET.

Accelerating Structure Assembly Sequence

9

Bonding of 5 test disks

Cut

Metallographical observation.. ..shows that grains are crossing the joining plane

Load pressure 0.28 MPa

Accelerating Structure Assembly Sequence

10

2. Brazing of couplers

x 2

x 4

3. Brazing of waveguides and RF flanges together

4. Machining of pockets for insertion of waveguides on the next brazing operation

5. Brazing of coupler body and waveguides together

Accelerating Structure Assembly Sequence

11

7. Brazing of inserts

X 8

8. Brazing of tuning studs

X 104

Alignment of stacks using ceramic pins

6. Brazing of 3 stacks with couplers.Angular alignment:

Diamond stylus reference line

Accelerating Structure Assembly Sequence, Cooling System

12

9. Brazing of cooling blocks (Cu)

Flexible hoses WITZENMANN

Standard fittings LEGRIS

10. Connection of fittings and hoses

- Power dissipation in the structure of about 0.3 kW;- Two parallel cooling circuits;- 8 cooling blocks each of 394 mm long;- Brazed directly onto the accelerating structure body;- Standard water connectors.

Accelerating Structure Assembly Sequence, Wake field monitor Feedthrough

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Custom design of feedthrough(Produced by Orient Microwave)

Copper adapter flange

Special connector

Electron-beam welding

TEST

11.Installation and sealing of Wake field monitor Feedthrough

- Based on standard feed-through- Special end of connector- Specially designed adapter from the standard feed-through to the accelerating structure body- The adapter is laser welded to the feed-through- Final, vacuum tight connection of the feed-through assembly is made by electron beam welding

Tuning System

14

PUSH

-PULL

Guide

Hammer

- Integrated tuning system;- Push-Pull Principle;- 4 tuning studs inside each cell.

Fabrication strategy

15

Prototype phase: Successfully finished

Series production phase:

Time/phaseStructure 1+2

machiningmeasurementcleaning+packagingready for transport

Structure 3+4machiningmeasurementcleaning+packagingready for transport

July August September October November December January

The End

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Thanks to:

Micha Dehler Germana Riddone

Alexandre Samoshkin Riccardo Zennaro

Serge LebetSaid Atieh

Vincent SibueAlexey Grudiev

REFERENCES[1] M. Dehler, et al, “X-Band RF Structure with Integrated Alignment Monitors” Phys. Rev. ST Accel. Beams 12, 062001 (2009).[2] J.P. Delahaye et al, “Towards CLIC feasibility”, paper presented at IPAC2010.[3] CATIA ® Version 5.16 © Dassault Systemes 1994-2008.[4] http://www.orient-microwave.com/[5] Juwen W. Wang et al. “Fabrication Technologies of the High Gradient Accelerator Structures at 100MV/m Range”, paper presented at IPAC2010.