WG4 SummaryRF Power, Industrial and Medical

‘Baron’ R Carter (CI-U of Lancaster)

T Johns (CPI)

P McIntosh (CI-ASTeC)

WG4 Goals• The group will review the current state of the art

of RF systems for X-band accelerators including:– high power sources, – RF distribution and – low-level RF systems.

• It will review industrial activity in the field including X-band accelerators for medical and security applications.

• The group will review the needs of future X-band accelerators and collate views about the R&D on sources, distribution systems and low-level RF systems required to meet those needs.

WG4 RF Power, Industrial and Medical Sessions• Monday 1st December (WG4 only):

– CPI Klystron Developments, Tony Johns (CPI)– Tech Industrial Solution for a Digital LLRF system, Borut Baricevic

(Instrumentation Technologies)– EMMA RF Distribution, Simon Davies (Q-Par Angus)– Compression of Frequency-Modulated Pulses using Helically

Corrugated Waveguide, Michael McStravick (U of Strathclyde)

• Tuesday 2nd December (All WGs Combined):– Thales Klystron Development at X-band, Sebastien Berger (Thales)– Discussion for X-band Sources (All)– Linacs for Hadrontherapy: CABOTO, a X-band CArbon BOoster for

Therapy in Oncology, Riccardo Zennaro (CERN)– Cost/MeV? (All)

• Wednesday 3rd December (Combined WG1 + WG4):– X-band Components, Igor Syrachev (CERN) – LLRF System for ILC Main Linac, Uros Mavric (Instrumentation

Technologies)

X-Band Vacuum Devices – T Johns (CPI)

VTX6389G5 VTX5681 VKX7864B VKX7841 VKX7993 ??

Helix TWT Coupled- Cavity TWT Klystron Klystron Klystron SBK

Frequency (GHz) 8.15 10 8.56 9.5 9.3 9.35

Power (MW) 0.0025 (CW) 0.1 (pk) 0.25 (CW) 0.65 (pk) 5.5 (pk) 2.7 (pk)

Efficiency (%) 59 n/a 44 28 43 43

Beam Voltage (kV) 15 45 51 8 120 76

Beam Current (A) 1 11 11 30 52 144

Under developm

ent

CPI Sheet Beam Klystron (SBK)

SBK Performance

• Beam transmission was 63% for shown parameters. • Best transmission was 94% at a much lower operating voltage. • Cathode position will be adjusted to improve transmission.

An Industrial Digital RF Stabilisation System – B Baričevič (ITech)

• LLRF system with 38 RF input channels (in 19” 2U chassis ).

• Built-in sophisticated RF system diagnostics.

• Reliable interlock system and chassis health monitoring.

• Cavity field stabilization and cavity tuning.

• Built in RF calibration and temperature stabilization systems.

• Phase and amplitude stability meets 4th generation light sources’ requirements.

• Compatible with normal-conducting and super-conducting RF systems in pulsed and continuous wave operation modes.

• X-band compliant (upto 12 GHz).

LLRF System Architechture

Application and Performance

~50 ppm

< 0.005 deg

EMMA RF Distribution – S Davies (Q-Par Angus)

100 kWIOT

Variable hybrids

Phase shifters

RF Cavity

BPMFQ

DQ

Variable Hybrid

Phase Shifter

• 180o phase change possible, with 400mm long structure.

• >26 dB return loss calculated.

Compression of Frequency-Modulated Pulses using Helically Corrugated Waveguide – M McStravick (U of Strathclyde)

• In a dispersive medium, if a pulse is modulated from one frequency to a frequency with a higher group velocity, the pulse will compress.

• Corrugation couples a counter rotating TE11 wave with a co- rotating TE21 wave on a 3-fold helix.

axial direction in dispersive medium

tail of pulse

Amplitude of microwave

Lower power microwave

front of pulse

higher power microwave

Helically Corrugated Waveguide

Measured Results

PIN switch

Low pass filter 8.0 -11.0GHz

Low Power

High Power

Klystron Characteristics

Frequency (f) 9.3 GHz

Pulsed output power 4.0 MW

Average output power 4 kW

RF pulse duration 5 µs

Pulse repetition rate 200 Hz

Duty cycle 0.001

-1 dB bandwidth >30 MHz

Perveance (K) 1.0 µA / V1,5

Efficiency 49 %

Expected lifetime > 30 000 hours

Operating conditions

Cathode voltage (V) 152 kV

Cathode current (I) 60 A

X ray shielding integrated

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 10 20 30 40 50 60 70

Input power (W)

Ou

tpu

t p

ow

er (

MW

)

152 kV nominal voltage

140 kV

130 kV

120 kV

Thales 9.3 GHz Klystron

46.5

47.0

47.5

48.0

48.5

49.0

49.5

50.0

50.5

51.0

51.5

52.0

9.26 9.27 9.28 9.29 9.30 9.31 9.32 9.33 9.34 9.35 9.36 9.37

Frequency (GHz)

Gai

n (

dB

)

Klystron Development in X-band – S Berger (Thales)

Klystron Parameters• Output waveguide

– WR112 flange– SF6 pressurization (3 bars)

• Water coolingTotal flow ~ 26 L / min

• Electron gun power supply– 152 kV / 60 A / 9.2 kW

modulator– Oil tank insulation– Heater voltage 15 V , current

13A

• Input driver– Input power = 30 W at

saturation

• Klystron– Height = 0,9 m– Weight ~ 60 kg– Output flange at 400 mm from

axis

• Electromagnet– Outer diameter = 500 mm– Weight ~ 350 kg– Power consumption ~ 4 kW

System size scales more with power and voltage than with frequency.

Focusing solenoid is a major contributor to weight, size and power

consumption.

X-band Sources - All

• Aim: Compile list of available/developing X-band sources:– List to be posted on XB08 indico server.– A Vliekes (SLAC) will start the ball rolling!

CArbon BOoster for Therapy in Oncology

The energy can be varied in 1-2 ms by changing the power pulses sent to the

20 accelerating modules

Linacs for Hadrontharapy (CABOTO) – R Zennaro

Cyclinac Concept

1 secondYesNoSynchrotron

-NoYesCyclotron

Time needed forvarying the energy

Energy variation by electronic

Means?

Beam alwayspresent duringTreatments?

Accelerator

1 millisecondYesYesCyclinac

The energy is changed by adjusting

the RF pulses to the modules

30-50 ms (*)

(*) With movable absorbers

Cyclinac Properties of the Accelerated Beams

21

CABOTO perspective view based on a ≤ 300 MeV/u cyclotron

p

p

p/Cp/C

p/C

Superconducting cyclotron by LNS/IBA (250 MeV protons and 3600 MeV carbon ions) is now commercialized by IBA

5 m

1st phase:32 cm protons

17 cm carbon ions

2nd Phase 32 cm protons

32 cm carbon ions435 MeV/u Carbon ions

22 m

300 MeV/u Carbon ions

Note: 3 GHz assumed here!

CABOTO at 12 GHz would be shorter and would consume less power (CNAO consumes 3-4 MW!)

LLRF System for the ILC Main Linac – U Mavric

• Major technical issues for ILC main linac:– Energy spread problems -> focus on the RF fluctuations as one

of the reasons of the energy spread.

• RF Disturbances:– LLRF disturbances that regulates the RF fields inside the

cavities.

• ILC LLRF system requires regulation of the vector sum of 26 signals (1 x LLRF unit controls 26 SRF cavities - three cryomodules).– I/O Signals: Reflected (26), Forward (26), Cavity Probe (26),

Beam monitor (3), Reference, Interlock signals.

• ILC performance requirements: – 0.5% amplitude, 0.24º phase r.m.s.

• LLRF architecture developed by B Chase et al @ FNAL

ILC RF System Architechture

LLRF System Tests• Bench Measurements (Open loop, closed loop).

• Measurements on ACC1 at DESY (Sept. 2007).• Measurements on CC2 at AØ PI at FNAL (Sept. 2008).

~0.016%

<0.05deg

WG4 Summary• Thank all industrial contributors for making a valuable

contribution to the workshop.• Number of X-band RF power sources available:

– Both from industry and labs (SLAC/KEK mainly).• Frequencies focussed ~9.3 GHz (radar) and 11.424 GHz (NLC/JLC)

– Adapting existing solutions to other X-band frequencies is feasible, but needs R&D (can be lengthy and expensive).

• All X-band structure installations require LLRF systems:– Provide controlled amplitude and phase delivery of Vacc.– Configurable digital solutions available to adapt to X-band

applications.

• Medical application identified which needs cost effective X-band system solution.– Collaboration initiated with CLIC, EPFL and PSI.– We all look forward to learning more of this system R&D.

THANK YOU