1. WG4 Summary RF Power, Industrial and Medical
‘Baron’ R Carter (CI-U of Lancaster)
T Johns (CPI)
P McIntosh (CI-ASTeC)

2. 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.

3. 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)

4. X-Band Vacuum Devices – T Johns (CPI)
Under development
VTX6389G5
VTX5681
VKX7864B
VKX7841
VKX7993 ??
Helix TWT
Coupled- Cavity TWT
Klystron
SBK
Frequency (GHz)
8.15 10
8.56
9.5
9.3
9.35
Power (MW)
(CW)
0.1 (pk)
0.25 (CW)
0.65 (pk)
5.5 (pk)
2.7 (pk)
Efficiency (%) 59
n/a 44 28 43
Beam Voltage (kV) 15 45 51 8
120 76
Beam Current (A) 1 11 30 52
144

5. CPI Sheet Beam Klystron (SBK)

6. 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.

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

8. LLRF System Architechture

9. Application and Performance
~50 ppm
< deg

10. EMMA RF Distribution – S Davies (Q-Par Angus)DQ
BPM FQ
RF Cavity
100 kW
IOT
Variable hybrids
Phase shifters

11. Variable Hybrid

12. Phase Shifter 180o phase change possible, with 400mm long structure.
>26 dB return loss calculated.

13. 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

14. Helically Corrugated Waveguide

15. Measured Results
Low Power
High Power

16. Klystron Development in X-band – S Berger (Thales)
Klystron Characteristics
Operating conditions

17. System size scales more with power and voltage than with frequency.
Klystron Parameters
Output waveguide
WR112 flange
SF6 pressurization (3 bars)
Water cooling Total 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.

18. 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!

19. Linacs for Hadrontharapy (CABOTO) – R Zennaro
Cyclinac Concept
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

20. Cyclinac Properties of the Accelerated Beams
Accelerator
Beam always
present during
Treatments?
Energy variation
by electronic
Means?
Time needed for
varying the energy
Cyclotron
Yes No -
30-50 ms (*)‏
Synchrotron No
Yes
1 second
1 millisecond
Yes
Cyclinac
The energy is changed by adjusting
the RF pulses to the modules
(*) With movable absorbers

21. CABOTO perspective view based on a ≤ 300 MeV/u cyclotron
p/C
Superconducting cyclotron by LNS/IBA (250 MeV protons and MeV carbon ions) is now commercialized by IBA
5 m
1st phase:
32 cm protons
17 cm carbon ions
2nd Phase
32 cm carbon ions
435 MeV/u Carbon ions
22 m
300 MeV/u Carbon ions
Note: 3 GHz assumed here! 21 21

22. CABOTO at 12 GHz would be shorter and would consume less power (CNAO consumes 3-4 MW!)‏22

23. 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 FNAL

24. ILC RF System Architechture

25. 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

26. 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 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.

27. THANK YOU