EMMA RF System Summary RF Requirements (S Berg): Aperture: –Aperture 34.7 mm (min) –Dispersion effects may increase by 3 – 4 mm Frequency: –Frequency range 5.5 MHz Voltage: –Nominal voltage of 120 kV/cavity –up to 180kV would be nice! –Not much interesting above 360 kV

RF Cavity Optimised geometry developed (E Wooldridge): ParameterValue Frequency (GHz)1.3 Shunt Impedance (M  ) 3.41 Realistic (80%)2.73 Qo23,000 R/Q120 Tuning Range (MHz)  0.8 Vacc (kV)120 Pdiss (kW)2.7 Ptot incl 30% Overhead* (kW) M  limit proposed in Jan07

Cavity Issues For the baseline (120kV) cavity design looks ok. Evanescent field not zero at the cavity flanges  large signals at BPM’s (50x too large!) Issues: –Asymmetric beam-pipe geometry –Damping e-m fields external to cavity –Moving the BPM further away –Making cavity beam pipe elliptical –Input coupler and tuning Using cavity HOMs as BPM?

RF Distribution Power sources identified (C Beard): –20 kW IOT e2v integrated amplifier –30 kW IOT Thales/CPI (non-integrated) –160 kW Klystron e2v

RF Distribution Integrated e2v IOT amplifier includes: –HVPS –Drive amplifier –Cooling –Local controls Non-integrated IOT and klystron needs these separately HVPS options: –1 large HVPS Baseline 30kV/5A (IOT) or 48kV/6A (Klystron) –Multiple small HVPS Baseline 30kV/1A for each IOT In early 2009, the SRS RF HVPS will become available: –50kV/10A DC supply –Configured to power a modulating anode klystron –Needs modifying to power proposed IOT/klystrons –Additional costs incurred (needs to be assessed)

RF Distribution With 19 cavities, distribution will be complicated regardless of solution adopted. –4 cavities/IOT –19 cavities/klystron Distribution options: –Waveguide hybrid splitters –Waveguide adaptive couplers –Combiner cavity (requires R&D) Individual cavity phase provided in distribution line (waveguide or coax) LLRF cavity phase compensation provided per amplifier distribution

Distribution Issues For the various distribution options: –Assess detailed costings –Investigate physical limitations

New Actions 1Produce final coupler and tuner designs ensuring optimum coupling at high powers and the required 6MHz bandwidth. Wooldridge 2Assess alternative cavity options e.g. Half re-entrant, Asymmetric beam pipe radius, etc. Wooldridge 3Evaluate the HOMs and effectiveness for Beam position monitoring Wooldridge 4Secure SRS PSU, and obtain a quote to modify the system for pulsed operation Beard/McIntosh 5Move BPMs further away from the cavityKelliher? 6Finalise the distribution layout for a) High Power IOT option b) Klystron Option Beard 7Evaluate additional system requirements for power sources, e.g. Cooling circuits, additional power supplies, pre-amp etc. Beard 8Produce comprehensive costs including Actions 4,5 & 6. Plus any additional staff effort required to complete the installation Beard/McIntosh