HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKCrab Cavity R&D
KEKB Crab Cavity GroupNAKAI Hirotaka

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

Overview of Recent R&D• Fabrication and measurement of2nd crab cavity• Design of cryostat for crab cavity• Consideration of installation ofcrab cavities in KEKBKEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKDesign of Crab Cavity• Crab cavity• Coaxial coupler• Stub support• Notch filter• RF absorber

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK•

Surface Preparation
Ordinary procedure:
1. Grinding
2. Barrel polishing
3. Electro-polishing (EP)
4. High pressure pure water rinsing (HPR)
5. Heat treatment
6. High pressure pure water rinsing (HPR)

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

Measurement Setup• Measurements
at 4.2 K– cavity only– with simplified
coaxial coupler

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKPerformance of 2nd Cavity

1010

Q0 109Cavity #1 without Coupler
Cavity #1 with Coupler
Cavity #2 without Coupler
Design Field

108
05101520Esp (MV/m)
KEKB Review Committee/20030211

253035• Ordinary
surfacepreparation
for #2• Comparison
with best
performanceof #1
NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

Improvement with 2nd EP

1010• Applicationof 2nd EP +HPR(~ 5 µm)

Q0 109108#2 - after 1st EP#2 - after 2nd EP#1 - without Coupler
Design Field

0510

KEKB Review Committee/20030211

152025Esp (MV/m)• Better than
#1303540
NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Cryostat Design Concept• Limitation of available space in tunnel– HER close to LER• Cryogenic transfer lines– helium and nitrogen• RF transmission lines• Long coaxial coupler– cooling and support
KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Cryostat Design (Top View)• RF porton side
• JackettypeheliumvesselsKEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Cryostat Design (Side View)• Cryogenic
ports ontop

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Cryostat Design (End View)• Interference of RF
coupler with LER
wiggler magnets

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Crab Cavity Installation• Research into crab cavities in KEKB
– one cavity in HER (determined)– one cavity in LER (proposed for more effect)• Cavities at Nikko Exp. Section (D10)– refrigeration system at Nikko– cryogenic port available in tunnel

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEKKEKB Review Committee/20030211

D10 Section of KEKBNAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

Cavity Location (Top View)

Cryogenic Transfer LineLER
HER
KEKB D10 Section
KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

Cavity Location (Cross Section)

HER LERKEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEKSummary 1• Established surface preparation• Cryostat– conceptual design completed– detailed design in progress– development of individual parts

KEKB Review Committee/20030211

NAKAI Hirotaka

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

Summary 2• Installation of crab cavities in KEKB
under consideration– location of crab cavities– modification of refrigeration system

KEKB Review Committee/20030211

NAKAI Hirotaka