EMMA Cavity Update Emma Wooldridge 27/02/07

Requirements Initial Design Cavity Options & Optimisation Available Designs Future Work

Requirements 19 Cavities Run from multiple IOTs or klystrons Voltage ~ 135 – 200 kV Shunt Impedance ~ 3 MΩ Beam pipe radius 19 mm Length 110 mm flange to flange –76 mm internal width

Shunt Impedance P = Power V = Cavity Voltage R sh = Shunt Impedance

Initial Design The ELBE bunching cavity For use on EMMA the shunt impedance must be increased from 1.4 MΩ

Cavity Options Modified ELBE design Scaled PEP II design Something else?

Optimising the Design Change –Width A –Height B –Nose cone Penetration C Radius D Angle E (All done whilst keep the frequency at 1.3 GHz)

Effect of Cavity Width

Nose Cone Angle

ELBE Like Design Nose cones have been made smaller Corners have been chamfered

PEP II Like Design Nose cones shallower Shape is flattened out

New Design Torus shape High Shunt Impedance

Nose Cone Radius

Comparison Practical shunt impedance assumes 80% of theoretical value

Field on axis Voltage / V Distance / mm BPM at 97mm

Voltage / V BPM at 97mm

Distance / mm Voltage / V BPM at 97mm

Closest BPM approx. 97 mm away from cavity centre Maximum voltage from cavity on BPM is 1 V.

Further Work Include realistic beam tubes Investigate half re- entrant design Add Coupler Add Tuners – 5.5 MHz Could cavity HOMs be used as BPMs?