First international Design Review of the MYRRHA accelerator. Spoke Cryomodule Design

First international Design Review of the

MYRRHA accelerator.Spoke Cryomodule Design

Bruxelles- 12/13 November 2012

Spoke Cryomodule Design - H. SAUGNAC - First international Design Review of the MYRRHA accelerator- Bxl 12/13 November 2012

SUMMARY

Introduction

General Specifications and Overview. Spoke Cavity Design. Power Coupler Design Cold Tuning System Design Magnetic Shielding Design Cryostat Design


INTRODUCTION

The main objectives for the first Mid-Period were :

Preliminary design of auxiliary components

Power Coupler- OK (Optimization remains)CTS OK - (Optimization remains)Magnetic Shield - Only conceptual

Preliminary design of spoke Cavity :

RF design - OKMechanical design - in-work (close to completion)Cavity Helium tank - only conceptual

Preliminary design of Cryostat

Conceptual design fixedCryogenic design fixed (in collaboration with ACS Task 4_2)Preliminary Overall sizing – OKProviding a first CAD model of the complete Cryomodule -OK


General Specifications and OverviewMAX T3_3 = Detailed design of the Spoke CM for End 2013

• Two Cells Spoke Cavity @ 352.2 MHz, b geom = 0.35

• T Op = 2 K, P mean loss RF = 10 W• P max RF losses fault tolerance ~ 17 W• E acc max nominal = 6,2 MV/m• E acc max fault tolerance = 8,2 MV/m• 2 Cavities per CM

• P Load = 2 to 16 KW CW . • P nominal max = 8 KW • P max fault tolerance = 16 KW

• No Focusing components inside CM• P Loss Static = 5W/m @ 2K• P max cavity helium tank = 1.5 bar• P design cavity helium tank = 2 bar

Spoke Section Reference pattern


SPOKE BAR GEOMETRY : feedback from the two Single-Spoke resonators and Triple-Spoke resonator fabrication (EURISOL)

Base (H field area): • no racetrack shape 3D weld seams are not easy (Spoke

bar-to-cavity body connection) • no cylindrical shape Hpk too high

Conical shape is chosen

Center (E field area): racetrack shape is ok

SPOKE CAVITY (1/4)


SPOKE CAVITY (2/4)


GOALSEpk/Eacc < 4.4

Bpk/Eacc (mT/MV/m) < 8.3

• CST MicroWave Studio 2012• Model created with the 3D CAD

tools of MWS• Symetries: ¼, BC: Magnetic planes,

Tetrahedral mesh, Nb tetrahedrons~10 000

• 1st mode calculated (TM010)• Optimisation of a dozen parameterOptimized RF parameters

Optimal beta 0.37Vo.T [MV/m] @ 1 Joule & optimal beta 0.693

Epk/Ea 4.29Bpk/Ea [mT/MV/m] 7.32G [Ohm] 109r/Q [Ohm] 217

Qo @ 2K for Rres=20 nΩ 5.2 E+09

Pcav for Qo=2 E+09 & 6.4 MV/m [W] 9.35

Lacc=0.315m=optimal beta x c x f

SPOKE CAVITY (3/4)


Epk

BpkLcav=435mm

Next steps:- Qext calculation- Lorentz forces detuning

factor- Mechanical optimization

SPOKE CAVITY (4/4)Preliminary mechanical FE simulations (ANSYS) have been performed on Model 0. Tenue to Vacuum (1 bar) 50 Mpa (V.M) With Donut stiffener

Mechanical longitudinal Stifness 5000 N/mm 25 Mpa for 1 mm elongation

Buckling Critical Pressure 2.5 bars Specification :P max inside helium Tank = 1.5 bars

Mechanical Eigen mode 60 Hz First mode with non global deformation RF frequency shift. (Without Donut Stiffener)


POWER COUPLEUR (1/2)A Power Coupler 350 MHz, 20 kW CW (designed), 50 W. WARM WINDOW

Was manufactured, in the framework of Eurotrans and successfully tested at 8 kW (amplifier limitation) CW on a 350 MHz, beta 0.15 Spoke cavity in a Cryomodule configuration.

Basis for design

2 CF16 ports for vacuum measurements.

1 port for electron emission measurement pick up

1 water cooling loop

Plain Copper Antenna

CF 63 on cavity

Thermal interception at 70 K (~15 W solid conduction) and ~ 10 K (~3 W solid conduction)

The Design (SNS Type) will be kept as if for MAX


POWER COUPLEUR (2/2)A conservative outer conductor lenght of 300 mm was taken to start the cryomodule design. Detailed simulations, for the thermal aspects remain to be done.A passive barometric compensation system (ESS Type) was studied in order to balance the atmospheric pressure force between the Coupler and the cavity train.

Vacuum vessel assembly flange


350 MHz Coax line

Warm Window block

Fixation rods to vacuum vessel fixed point)

Fixation rods to coupler (mooving point)

Barometric compensation bellow

Thermal contraction bellow

80 K Thermal interception

5/10 K Thermal interception

Sam

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Cold Tuning System

One CTS was designed and tested on a Beta = 0.15, 350 MHz Spoke cavity in the framework of Eurotrans. The main parameters ( Cavity RF frequency sensitivity, Stiffness, Helium Tank relevant dimensions…) are similar with the MAX Spoke cavity. This design is taken for the Spoke MAX CTS Design. In addition an optimized design, in term of stiffness, is under study on a similar CTS for ESS 350 MHz Spoke cavities.

CTS (CEA ‘Soleil’ Type) for Eurotrans 350 MHz Spoke cavity

General studies on reliability (C&C, reliability of stepping motor and reductor) are conducted in the frame of the MAX Task T3_1.

The CTS detailed Design will be achieved once the Cavity Helium Tank is completed..


Magnetic ShieldingNo detailled study is done yet on the Magnetic Shielding. No simulation on the magnetic field effect and the sizing of the Shield.As conceptual design we assume that the Magnectic Shield is : - Made of Cryoperm- Cooled down actively- Composed of two skins

Cavity Cool Down Phase

During Cool down phase the Cryoperm is first cooled and reach the optimal temperature (below 70 K) before the cavity becomes SC. In Stationary operation the shield only attached to the cavity helium tank reach an equilibrium temperature.Assemblies of the different parts of the shield are made with screws Requires long cooling tube ~ 8 m per cavity.This concept was succefully tested on SPIRAL2 CM B.

A more practical concept as trapping the cryoperm inside the Helium Tank may be considered….

SPIRAL 2 Concept


Cryostat Design / Overview


Warm valve (No Cold Valves)

Adjustable supporting posts

Power couplers

Cavity train supporting frame

Cryogenic line connection

Level measurement and relief valves circuit chimney

2 K phase separator reservoir

Cold Tuning System

Actively cooled down magnetic shield

Barometric compensation

5/10K heat interception loop

Copper thermal shield (40/80K 4/3 bars)

Sliding and adjustable fixture to cavity train supporting frame (TTF Type)

Cavity pumping port

Coaxial 350 MHz Line

Cryostat Design / Overview


Diagnostics box position and size ?.Longitudinal gain of space is still possible.

Cryostat Design / Assembly – Cold Mass

Inside Clean Room (Iso 4) Outside Clean Room


Cavity + Coupler, first assembled on Clean Room trolley.

Different components assembled on the CM suporting frame.

This frame goes outside and inside Clean room

Cryostat Design / Assembly - Cryostating


Cryostat Design / Cryogenic Loops

Internal CM circuitery Q T max F Int & L t CD DP max

40/80 K Loop Cool Down (Ghe 4/3 bars) 2g/s NC 10 mm, 15 m 9 hr 115 mbar

40/80 K Loop Stationary (Ghe 4/3 bars) 110 W 86,2 K 10 mm, 15 m NC 4 mbar

5/10 K Loop (Lhe 3/1 bar) 15 W 10 K NC 1 mbar

Mag. Shield Cool Down (LHe 1,2/1 bar) 10 mm, 8 m 0.3 hr 180 mbar

Cavity Cool Down (Lhe 1,2/1 bar) 1,2 hr

Cavity Stationary 30 W <10-1 mbar


Cryostat Design / Pressure Security

Accident : Insulation Vacuum breakage. Volume LHe ~ 100 litresSurface He loop ~ 2,6 m2

q = 6 kW/m2 (CERN, Conservative) m’= 742 g/sT fluid out < 20 KP cav max =1.5 bar

1 x Burst Disk (K=0.6, F = 60 mm) P discharge = 1.33 bar+/- 10%m’ max = 750 g/s @ T > 20 K

2 x Relief Valve (Circle seal type 500 F 1 ‘’) P oppening = 1.15 bar+/- 5%m’ max (each)= 120 g/s @ T = 20 K.Prevent overpressure from Cool Down operation, Quench…without breaking the Burst Disk…


Cryostat Design / Thermo-Mechanical Evaluations

Conservative (To Be optimized) Q* 300K70K Q 70K2K Q 70K10K Q 10K2K

Cavity frame- Solid Conduction (With 5K/10K Heat Sink) 22,6 W NC 1,6 W 0.11 W

Power Coupler - Solid Conduction 30 W NC 6 W < 0.1 W

Beam Tube solid conduction (300K2K Transition) 1,6 W 0,1 W NC NC

Burst disk pipe Solid Conduction (to be evaluated) < 2 W < 0.1 W

Thermal radiation (30 layers MLI @60K ; 10 layers MLI @2K ) 30 W(6W/m2)

0.2 W (0,06 W/m2)

NC NC

Thermal radiation (Beam tubes, measurement chimney) 2,74 W 0.1 W NC NC

Thermal radiation Power Couplers (to be evaluated) < 5W ??? < 2W ?? < 2W ??

Instrumentation, Wiring (to be evaluated) < 5 W < 0.5 W

Cavity Frame (To be Optimized) D X D Y* D Z* s V.M.

@ 300K (100 Kg/Cavity) -0,1/+0,14 -0,9/+0,9 -0,6/+0 78 MPa

@ Cold ( 100 Kg/Cavity + thermal contraction) -3,6/+0,2 -0,5/+0,5 -2/+0 78 MPa

*Require Optimizations Q 70 K < 100 W To be reduced, Q 5K/10K < 10 W, Q 2K < 3,2 W


Cryostat Design / Accelerator Hall Cross section


Valve box not designed yet. Can be optimized to gain space (parallepipedic instead of cylinder).Height of the hall remains to be checked taking into account handling (tools, strategy…) of the different components.

The vertical position of the LINAC depend on other components as elliptical cavity CM. Diameter, coupler lenght and Coupler doorknob and wave guides are in a first approximation compatible with a 1,5 m beam axis height.

700 MHz Elliptical cavity DoorKnob

Preliminary LINAC Tunnel Dimensions

RF amplifiers, electronic…Hall

Conclusions


Conceptual and preliminary designs achieved for the main components.

Cavity RF optimization achieved, mechanical optimisation in-work

Components (CTS, Coupler, Cryostat…)optimization to be achieved in June 2013

CAD detailed design & assembly tooling from June 2013.

A Spoke cavity prototype without helium tank is planed to be manufactured (order before end 2012…). Cryogenic tests will be performed in 2013 in order to validate the RF Design and the Manufacturing process.

Documents

First international Design Review of the MYRRHA accelerator. Spoke Cryomodule Design