HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

1

KEKCrab cavity:Cryostat
KEKB Crab Cavity R&D Group(presented by NAKAI Hirotaka)

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

2Overview

KEK• Design of cryostat• Results of Numerical Analyses– Buckling– Stress etc.

• Status of cryostat manufacturing– Magnetic shield– Frequency tuner– Vacuum vessel etc.

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK3Cryostat Design Concept• Jacket-type liquid helium vessel• Coaxial coupler with bellows forfrequency tuning: 28.3 kHz/mm• Stub support for long coaxial coupler
for mechanical support and cooling ofcoaxial coupler tip• Jacket-type magnetic shield aroundcavity
KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKTop View

4

Cryostat Conceptual Design
RF Input coupler
Magnetic Shield (Jacket Type)Frequency Tuning
by Adjusting Distance

RFAbsorber
StubSupport

I.D. 240

Coaxial Coupler

I.D.100

Bellows
RF Monitoring
PortKEKB Review Committee/20050221

Liq. HeRFAbsorber

Liq. HeCrab Mode
Reject Filter(Notch Filter)

80 K Liq. Nitrogen Shield

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

5Cryostat Design (Side View)

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

6

Cryostat Design (Top View)

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

7Cryostat Design (Front View)

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

8Cooling SchemeKEK

Cryogenics System
Safety Valve

Monitor Port
Liq. He Level Meter

Liq. He (Supply)
He Vapor (Return)
Liq. N2 (Supply)
Liq. N2 (Return)LN2 80K Shield
LN2 80K Shield

Thermo Sensor
Pressure
VacuumMain He Vessel

Sub He Vessel

HeaterKEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

9Cooling Water System

KEK

Cooling Water
Input Coupler

Liq. He In
Coaxial Coupler

Stub Support

Beam

RFMonitor

Sub He Vessel

RF Monitor

RFMonitor

Gas He Out
Coaxial Coupler Position

Main He Vessel
Kick Voltage

KEKB Review Committee/20050221

Temperature
Thermo Sensor

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

10Heat Leak to Cryostat

KEKHeat Leak [W]Heat Leak PathHeat Transfer Mode

Inner Conductor

To 80 K Region To 4 K Region
Stainless Steel Tube

––

1.8

Outer Conductor

Stainless Steel Tube
Copper Plating

24.2

5.4

0.8
1.1
1.5

Input Coupler

Outer Conductor

Stainless Steel Tube
Copper Plating

13.0
3.2

1.0
1.9

Beam Pipes

Beam Pipes

Stainless Steel Tube
Copper Plating

41.2
6.9

1.9
1.9

Outer Sleeves (2 Sleeves)

1.4
3.4

0.10.3

Cavity Supports (4 Wires)–0.6–––0.7
0.6

10.6––0.4

109.3

14.6

Coaxial Coupler

Conduction
TunerSupports

Copper Plating

Inner Rods (2 Rods)

80 K Shield Supports
LHe Transfer Tubes (2 Tubes)

Plumbing

Liquid Level Sensor Support
Safety Valve Plumbing

Wiring

Thermocouples, Cables, etc.
Vacuum Vessel to 80 K Shield

Radiation

80 K Shield to LHe Vessel

Total Amount of Heat LeakKEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK11Cavity Model for Analysis

Nodes: 32808Elements: 28716
KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK12

Buckling Analysis of Cavity

1st Order Mode
Buckling Load: 0.7772 MPa
KEKB Review Committee/20050221

2nd Order Mode
Buckling Load: 0.8500 MPa
NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

13

Helium Jacket Model for Analysis

Nodes: 114716
Elements: 109426
KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK14

Buckling Analysis of Helium Jacket

1st Order Mode
Buckling Load: 0.3218 MPa
KEKB Review Committee/20050221

2nd Order Mode
Buckling Load: 0.3219 MPa
NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK15

Stress Contour of Cavity (1)SBP Cavity Cell:
27.2 N/mm2

SBP Cavity Cell
Vicinity of Rib:
34.1 N/mm2

Tresca stress contour in middle plane
KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

16

Stress Contour of Cavity (2)Cavity Cell Equator:
31.8 N/mm2

Input Coupler End:28.7 N/mm2

LBP Cavity:
25.5 N/mm2

LBP Cavity Cell
Vicinity of Rib:
32.8 N/mm2
Tresca stress contour in middle plane

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

17

Stress Contour of Helium Jacket (1)LBP End:
108 N/mm2

KEKB Review Committee/20050221

LBP End Plate:
108 [N/mm2]

Tresca stress contour in middleplane

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

18

Stress Contour of Helium Jacket (2)Tresca stress contour in middle plane

SBP End Plate:
71.9 N/mm2
KEKB Review Committee/20050221

SBP End:70.2 N/mm2
NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

19

Frequency Tuner Schematic

KEKInput Coupler

Mechanical + Piezo

Bellows
Stub Support
Beam

Coaxial Coupler

RF Monitor

Main He Vessel

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

20

Frequency Tuner (1)Side View

KEKB Review Committee/20050221

Top View

DriverMechanical + Piezo

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

21

Frequency Tuner (2)Front View

KEKB Review Committee/20050221

Side View

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK22

Test Stand for Frequency Tuner

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

23

Magnetic Shield (Jacket Type)

KEK

Segmentation
Crab Cavity

3t

10R60
D100

D100127

D600
R300

R300
R600300300300

D320

Large Beam Part

D32090Large Beam Pipe
250

D100250

D328
20Cell Part

127

Crab Cavity Cell
5612720
D278

Small Beam Pipe

D270

KEKB Review Committee/20050221

200

Small Beam PartNAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK24

Magnetic Shield (Jacket type)

Material: Permalloy, 3 mm thick
KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKKEKB Review Committee/20050221

25

Copper Bellows

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

26

Copper Bellows

KEK

Stress Analysis by ABAQUS

R = 3 mmt = 0.4 mm
I.D. 188

Stress σ (MPa)

Pitch 17.9 mm

Δ L = 1 mm

Allowable Deformation ΔL of Bellows

ΔL allowable (mm)Youngʼs Modulus: E = 127,000 MPa
Poissonʼs Ratio: ν = 0.345000 cycles
for 6-cell Bellows

Thickness of Bellows (mm)KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK2780 K Thermal Shield Structure
Key Bar (S.S.)
φ 4 mmAluminum
Laminated Collar(t=1.5 mm)

Insert & Weld

Aluminum 80 K
Thermal Shield(t=2 mm)KEKB Review Committee/20050221

Liq.Nitrogen
Pipe S.S.
φ 42.7mm

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

2880 K Thermal Shield

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKKEKB Review Committee/20050221

29Vacuum Vessel

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

30

End Shell Hydroforming

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

31Assembled End Shell

KEKB Review Committee/20050221

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

32Summary• Cryostat design almost completed andnumerically analyzed• Prototype cryostat for assembly checkand cooling test under construction• Parts Fabrication in Progress

KEKB Review Committee/20050221

NAKAI Hirotaka