13 th April 2007FFAG 07 Carl Beard EMMA RF System Carl Beard, Emma Wooldridge, Peter McIntosh, Peter Corlett, Andy Moss, James Rogers, Joe Orrett ASTeC, Daresbury Laboratory Design Parameters Cavity Requirements Power Sources Distribution options

13 th April 2007FFAG 07 Carl Beard EMMA RF Specification Machine ParametersValue Frequency (GHz)1.3 Number of Straights21 Number of Cavities19 Total Acc per turn2.3 MV Upgrade Acc per turn3.4 MV Beam Aperture40mm RF Bunch Length1.6 ms RF Repetition rate10 Hz Phase Control0.02 o Amplitude Control2x10 -4

13 th April 2007FFAG 07 Carl Beard Design Parameters 1.3 GHz chosen for EMMA to both: –Match ERLP RF systems and –To utilise developed RF infrastructure: RF power sources LLRF systems Compact Size Updated RF cavity design constraints: –Beam aperture 40mm –Cavity length (flange to flange) 86mm (110mm) –Accelerating voltage per cavity of 120kV (for 19) up to 180kV Future Upgrade –RF power source availability i.e. IOTs or klystrons

13 th April 2007FFAG 07 Carl Beard Proposed Cavity Design ParameterValue Frequency (GHz)1.3 Shunt Impedance (M  ) 4.3 Realistic (80%)3.44 Qo23,000 R/Q120 Tuning Range (MHz) +1.5MHz to - 4MHz Vacc (kV) Pdiss (kW) Ptot incl 30% Overhead * (kW) * LLRF + Distribution 90mm 86mm 40mm

13 th April 2007FFAG 07 Carl Beard Cavity Tuning Single Tuner Optimised for required tuning range +1.5 to – 4 MHz. Reduction in Rsh to 4.15

13 th April 2007FFAG 07 Carl Beard RF Leakage Broadening of the beam pipe leads to leakage of RF flux The field strength has to be low enough to avoid interference with the BPMs At 150 mm, the fields have decayed to 0.1V Requirement is <0.5V Closest BPM is located ~200mm away

13 th April 2007FFAG 07 Carl Beard Options Thales IOT 30 kW (Pulsed) No PSU CPI IOT 30 kW (CW) No PSU etc e2v Amplifier 20 kW (Pulsed) e2v Klystron 160 kW (CW) >170 kW (Pulsed)

13 th April 2007FFAG 07 Carl Beard IOTs e2v 116LS –16kW CW integrated amplifier system –Dual 19”rack configuration –Integrated HVPS, IOT and controls –Tests at DL in Mar 2006  achieved 20kW pulsed at 1.5ms/20Hz –Multiple IOTs to be powered from 1 PSU Thales TH713 –20kW CW independent IOT –Thales are developing an IOT amplifier solution –Tests at Thonon in Sept 2006  achieved 30kW pulsed at 1.5ms/20Hz CPI CHK51320W –30kW CW independent IOT –CPI are developing IOT amplifier solution –>30kW Pulsed should be possible, but no indication of figure available.

13 th April 2007FFAG 07 Carl Beard IOT Options PSU, Controls and Pre-amp required for CPI/Thales IOT (integrated Amplifier is being developed for both) 20 kW e2v IOT30 kW CPI/Thales IOT Number of RF Cavities19 Number of RF Power Sources3724 Cavity Rsh (M  ) 3.4 Vacc/Cavity (kV) Cavities/RF power source2x6 / 1x75x3 / 2x21x9/1x103x5 / 1x4 RF Power/Cavity (incl o/h) (kW) Distribution and Control Overhead (%)30 Total Ring RF Power (kW) Max Ring Power Available (kW) RF Power Overhead (kW)8.7 (17%)24.1 (21%)8.7 (17%)4.1 (3.5%)

13 th April 2007FFAG 07 Carl Beard Klystron Options 160kW (possibly 170 kW) klystrons are available from e2v PSU, Pre-amp, Cooling systems required PSU Requirements - 45kV, 5.8A 160 kW e2v Klystron Number of RF Cavities19 Number of RF Power Sources11 Cavity Rsh (M  ) 3.4 Vacc/Cavity (kV) Cavities/RF power source199/10 RF Power/Cavity (incl o/h) (kW) Distribution and Control Overhead (%) 40 Total Ring RF Power (kW) Max Ring Power Available (kW)160 RF Power Overhead (kW)78.3 (60%)44.1 (42%)

13 th April 2007FFAG 07 Carl Beard Power Source Options Klystron Overhead large, even at 180 kV per cavity Single device xCost for the PSU and time to reconfigure very large xSingle failure of the Klystron would result in long down time xEfficiency and linearity of Klystrons mean the power delivered to the cavity is much reduced IOT Off the shelf product – fast replacement Integrated amplifier would be simplest option High efficiency xMinimal overhead required for power xSingle failure of the Klystron would result in long down time xFull reconfiguration would be required to upgrade to 180 kV per cavity.

13 th April 2007FFAG 07 Carl Beard PSU’s On-site Thales PSU 0.5 MW 10 Amps, 50 kV. Currently in use on SRS Available from 2009, Upgrade for EMMA is costly Crowbar Power Supply 0.8 MW 52 kV – 16 Amps Original SRS/NINA Klystron PSU Needed to operate 2 e2v klystrons

13 th April 2007FFAG 07 Carl Beard Distribution Losses RF Losses in Waveguide << Losses in Coax. –To minimise losses waveguide needs to be close to the cavity Coaxial Lines Losses can be as high as 0.5dB –Mainly due to connectors –Also dependent on length of Line Connector Losses = ( dB x F(GHz)) x 2 Cable Losses = dB/Foot x 10 = 0.5 dB Total Losses = 0.6 dB Therefore Assume 1 dB Losses (20%) For a 2 M Coaxial Cable

13 th April 2007FFAG 07 Carl Beard 7dB Cascaded Distribution 3-Stub Tuner %33%25%20%16.6%14.3% 3 dB4.8 dB6 dB7 dB7.8 dB8.4 dB 3dB 4.8dB 6dB IOT The same regardless of number of splits. Compact System Single Cavity Amplitude Phase and Amplitude not possible Klystron option similar (1 Klystron feeds all 19 cavities) Load Circulator

13 th April 2007FFAG 07 Carl Beard 7dB IOT Distribution (Split) IOT Fewer Circulators are required Odd Number splits complicate the system. Single Cavity Amplitude Phase and Amplitude not possible Large Waveguide Distribution 3dB

13 th April 2007FFAG 07 Carl Beard LLRF Distribution Master Oscillator Amplitude Control SS Amp IOT Phase Shifter Mixer In the combined systems only takes feedback from a single cavity Phase control of the cavity group is possible Individual IOTs for each cavity required for separate Amplitude and Phase adjustment The string of cavities would be phased locked to the control cavity Comparator Level Detector Comparator

13 th April 2007FFAG 07 Carl Beard Cavity Splitter Klystron + Vastly Simplified RF distribution - Requires development – RF and Mechanical Design IOT

13 th April 2007FFAG 07 Carl Beard Prototype Combiner

13 th April 2007FFAG 07 Carl Beard Summary Cavity has been designed with sufficient tuning range, and high efficiency to reduce the demand on the RF power requirement Fields are sufficiently small to avoid interference with BPMs Cascaded RF Distribution would be the optimum since space is valuable. Fast, individual cavity amplitude and phase control not possible with this system. Slow Phase adjustment is possible through motorised Phase shifters. Klystron option would have the highest risk in case of Klystron failure. IOT Amplifier option would be the advised option.