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,

13th April 2007 FFAG 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


EMMA RF SpecificationMachine Parameters Value

Frequency (GHz) 1.3

Number of Straights 21

Number of Cavities 19

Total Acc per turn 2.3 MV

Upgrade Acc per turn 3.4 MV

Beam Aperture 40mm

RF Bunch Length 1.6 ms

RF Repetition rate 10 Hz

Phase Control 0.02o

Amplitude Control 2x10-4


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


Proposed Cavity Design

Parameter Value

Frequency (GHz) 1.3

Shunt Impedance (M) 4.3

Realistic (80%) 3.44

Qo 23,000

R/Q 120

Tuning Range (MHz) +1.5MHz to -4MHz

Vacc (kV) 120 180

Pdiss (kW) 2.1 4.7

Ptot incl 30% Overhead* (kW) 2.73 6.1

* LLRF + Distribution


Cavity Tuning

10mm tuner

1.2965

1.297

1.2975

1.298

1.2985

1.299

1.2995

1.3

1.3005

1.301

1.3015

1.302

0 5 10 15 20 25

Penetration

Freq

uenc

y G

Hz

•Single Tuner

•Optimised for required tuning range

•+1.5 to – 4 MHz.

•Reduction in Rsh to 4.15


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


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)


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.


IOT Options• PSU, Controls and Pre-amp required for CPI/Thales IOT

(integrated Amplifier is being developed for both)

20 kW e2v IOT 30 kW CPI/Thales IOT

Number of RF Cavities 19 19 19 19

Number of RF Power Sources 3 7 2 4

Cavity Rsh (M) 3.4 3.4 3.4 3.4

Vacc/Cavity (kV) 120 180 120 180

Cavities/RF power source 2x6 / 1x7 5x3 / 2x2 1x9/1x10 3x5 / 1x4

RF Power/Cavity (incl o/h) (kW) 2.73 6.1 2.73 6.1

Distribution and Control Overhead (%)

30 30 30 30

Total Ring RF Power (kW) 51.3 115.9 51.3 115.9

Max Ring Power Available (kW) 60 140 60 120

RF Power Overhead (kW) 8.7 (17%) 24.1 (21%) 8.7 (17%) 4.1 (3.5%)


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

160 kW e2v Klystron

Number of RF Cavities 19 19

Number of RF Power Sources 1 1

Cavity Rsh (M) 3.4 3.4

Vacc/Cavity (kV) 120 180

Cavities/RF power source 19 9/10

RF Power/Cavity (incl o/h) (kW) 2.73 6.1

Distribution and Control Overhead (%)

40 40

Total Ring RF Power (kW) 51.3 115.9

Max Ring Power Available (kW) 160 160

RF Power Overhead (kW) 78.3 (60%) 44.1 (42%)


Power Source Options

Klystron Overhead large, even at 180

kV per cavity Single devicex Cost for the PSU and time to

reconfigure very largex Single failure of the Klystron

would result in long down timex Efficiency 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 efficiencyx Minimal overhead required for

powerx Single failure of the Klystron

would result in long down timex Full reconfiguration would be

required to upgrade to 180 kV per cavity.


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


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 = (-0.012 dB x F(GHz)) x 2Cable Losses = -0.05 dB/Foot x 10 = 0.5 dBTotal Losses = 0.6 dB

Therefore Assume 1 dB Losses (20%)For a 2 M Coaxial Cable


7dB

Cascaded Distribution

3-Stub Tuner

2 3 4 5 6 7

50% 33% 25% 20% 16.6% 14.3%

3 dB 4.8 dB 6 dB 7 dB 7.8 dB 8.4 dB

3dB4.8dB6dBIOT

•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


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

3dB

3dB


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


Cavity Splitter

Klystron

+ Vastly Simplified RF distribution

- Requires development – RF and Mechanical Design

IOTIOT


Prototype Combiner


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.

Documents

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,