1. CLIC DB injector front end update on the work package
Description of the work package
Drive Beam Klystron status
Overview of the ongoing work
Collaborations
Outlook, planning

2. CLIC DB injector front end update on the work package
Original: Work package in EV, ‘CLIC0 Drive Beam’, with the goal to built a full injector up to 12 MeV for integrated beam tests until 2017
Reduced scope: ‘CLIC Drive Beam injector R&D’ with the goal to do key hardware development and independent tests to enable the construction of an injector after 2017

3. Modulator-klystrons, 1 GHz, 15 MW
CLIC DB front end
Modulator-klystrons, 1 GHz, 15 MW
IOTs ?, 500 MHz
Diagnostics
Gun
SHB 1-2-3 PB
Buncher
Acc. Structures
~ 140 keV
~ 3 MeV
~ 12 MeV
Gun, sub-harmonic bunching, bunching, three accelerating structures,
5 long pulse klystrons and modulators, diagnostics, beam line

4. Modulator-klystron, 1 GHz, 20 MW
CLIC DB front end
Hardware R&D
Modulator-klystron, 1 GHz, 20 MW
500 MHz
Gun
~ 140 keV
Diagnostics
SHB 1
Acc. Structures
Reduced scope: Gun, sub-harmonic buncher, rf-unit, diagnostics, injector design

5. What is part of the work package ?
Development and validation of an rf unit for the CLIC DB (Modulator, Klystron, Accelerating-Structure, test stand)
Design of the injector, mainly beam dynamics, SHB design +prototype, beam diagnostics design + prototypes
Design, prototype and test of a electron source suitable for the DB injector, gun test area, diagnostics
Contributions from different CLIC activities, collaborations and CERN groups

6. 10 MW L-band klystrons for ILC
In terms of achieved RF efficiency, the klystrons with RF circuit adopted by Toshiba and CPI provides values very close to the 70%, as is specified in CLIC CDR (67.8% for CPI and 68.8% for Toshiba. These values validate the feasibility of a slightly higher efficiency with minimised design/fabrication efforts, when scaled in frequency down to 1.0 GHz.
Igor Syratchev

7. Gun topology scaling scenarios
20 MW L-band klystron for CLIC
Our study of scaling the existing technology shows reasonable evidence that 6 beam MBK with 20 MW peak RF power might be the best compromise for the CLIC-type L-band klystron, providing high (>70%) efficiency, long (> hours) life time and operated at a reasonable (164 kV) cathode voltage. This choice also may be the most cost efficient.

8. Status: Preparation of call for tender
Tentative klystron
parameters
PARAMETER
VALUE
UNITS
RF Frequency
Bandwidth at -1dB
RF Power:
Peak Power
Average Power
RF Pulse width (at -3dB)
HV pulse width (at full width half height)
Repetition Rate
High Voltage applied to the cathode
Tolerable peak reverse voltage
Efficiency at peak power
RF gain at peak power
Perveance
Stability of RF output signal at nominal working point
RF phase ripple [*]
RF amplitude ripple
Pulse failures (arcs etc.) during 14 hour continuous test period
Matching load, fundamental and 2nd harmonic
Average radiation at 0.1m distance from klystron
Output waveguide type,
≥ 1
≥ 20
150
165 50
tbd, ≤ 180
tbd
65 ≥ 67 ≤ 70
tbd, > 48
±1 (max)
< 1-2
< 1
WR975 pressurised
MHz MW kW μs Hz kV % dB
μA/V1. 5
RF deg
VSWR
μSv/h
2-3 bar
Status: Preparation of call for tender

9. Klystron Modulator and
test stand
Status: see presentation from D. Aguglia
Create a 1 GHz test stand together with TE-EPC to test the two prototype modulators and klystrons into loads
Establish HV and rf- measurements to study and demonstrate stability of the DB rf-system
Use facility to test DB accelerating structure and components with high power under nominal parameters
1 GHz test stand (needed in 2015):
Aim to share high power test stands in the rf group, possible candidate sides (~50 m2 needed): Bldg. 112 (LHC), 150 (CLIC), 152 (Linac4)

10. Sub-harmonic bunching system
Status:
RF design existing, mechanical design advanced,
Next: launch prototype (in aluminum ?)
Power source:
500 MHz, kW, wide band (60 MHz) sources needed for fast phase switching. Started to discuss with industry.
Hamed Shaker, see IPAC paper

11. DB injector review and optimization
Final phase space at 50 MeV after re-optimization of the injector with realistic rf parameters, 4% satellites, good longitudinal phase space
Shahin Sanaye Hajari, see as well IPAC paper

12. DB injector review and optimization
Shahin Sanaye Hajari, see as well IPAC paper
Total losses reduced from 30% to 11%

13. Gun Test Facility Gun test area:
former GTF available, Bldg. 162-R-004/008, needs some refurbishment

14. Gun simulations Using EGUN
e ~ 12 mm mrad

15. Gun simulations
Emittance vs voltage

16. Jacques Gardelle Contour plots of field components at t=35ns
Typical MAGIC snapshot: particle positions in r-z
Typical MAGIC snapshot: kinetic energy of particles along z
29/01/2013

17. DB-Gun strategy and planning
1-2/2013
3-4/2013
1-2/2014
3-4/2014
SLAC design study based on YU156
SLAC mechanical design with YU156
Fabrication
Test
Concept for GTF
Prepare local and purchase equipment
HV-test for PS ready install equipment
Gun test
Design GUN
CERN-CESTA based on YU796 and YU156 modular ?
Mechanical design based on YU796
Modulator design CESTA
Prototype
Prototype at CERN
Concepts for HV deck electronics
Design of pulser electronics
Fabrication and tests
Ready for use

18. Beam diagnostics Gas Jet Monitor
Fire a supersonic gas jet across the beam pipe
Jet can be arranged as a ‘screen’ at 45 to beam
Most gas collected in a receiving chamber
Advantages over residual gas monitor:
Cross-section, not separate profiles
Localised higher pressure -> faster profile measurement
Reduce vacuum contamination & losses
Two limits to resolution:
Beam Space Charge -> Need strong B and E field for extraction
Gas Jet Thickness -> Possible matter-wave focusing with Zone Plate
Test Stand at Cockcroft Institute, U.K.
Beam
Jet generation
Pumping
Collection chamber
Gas source
Shaping

19. Adam’s Summary Interceptive monitors would be destroyed
Profile measurement for the CLIC drive beam poses challenges due to very high intensity:
Interceptive monitors would be destroyed
Strong space charge effect makes ionisation monitors tricky to implement.
Care needed to avoid wakefields
A number of options are being explored
A varied ‘toolkit’ of solutions will probably needed to cover the full DB energy range

20. (existing or under discussion)
Collaborations
(existing or under discussion)
CEA-CESTA: Gun and injector design, HV-modulator for the gun
IPM: Injector and SHB design
NCNR: DB accelerating structure and DB beam dynamics
IFIC: DB diagnostics, BPM and profile monitor
SLAC: gun design
Modulator: see Davide’s presentation
Klystron: collaboration with industry

21. Rough planning, milestones
Outlook,
Rough planning, milestones
Task
2013
2014
2015
2016
Gun test area
prepare gun test area
ready for first tests
testing with HV modulator
testing
Gun
design
Prototype, first tests
gun tests
SHB Buncher
fabrication
testing low power
testing high power
500 MHz power source
specifications
purchase
needed for test
1 GHz structure
specs, mech. design
construction
low power test
high power test
Diagnostis
tests in gun area ?
LLRF
specs
fabrication+test
ready for klystron test
1 GHz klystrons
tender, contract
Design review
Receive first prototype
Klystron 2
1 GHz Modulator
R&D
Receive first MDK
MDK2
1 GHz rf test stand
specs, location
prepare
Receive MDK, klystron
Ready for testing
RF stability
Measure CTF3, DESY?
Measure SLAC ?

22. END

23. CLIC DB injector specifications
Parameter
Nominal value
Unit
Beam Energy 50
MeV
Pulse Length
140.3 / 243.7
ms / ns
Beam current
4.2 A
Bunch charge
8.4 nC
Number of bunches
70128
Total charge per pulse
590 mC
Bunch spacing
1.992 ns
Emittance at 50 MeV
100
mm mrad
Repetition rate Hz
Energy spread at 50 MeV 1
% FWHM
Bunch length at 50 MeV 3
mm rms
Charge variation shot to shot
0.1 %
Charge flatness on flat top
Allowed satellite charge
< 7
Allowed switching time 5

24. Task description Task What is planned Who is involved Klystron
Tender, Purchase, Follow up, reception
EV, BE-RF; Steffen, Igor, Gerry
Modulator
Develop, follow up, reception, test
TD, TE-EPC; David + Collaborations
Test stand, LLRF, WG-system
Prepare test area to test klystron with modulator into load and structure, enable measurements
EV, BE-RF; Steffen, Nuria, Gerry, Luca
TD, TE-EPC; David
RF,HV stability
Measure existing systems to check specifications and possible solutions
EV, BE-RF, TE-EPC, BE-ABP
Acc-structure
RF-design, Mechanical design, built prototype, test
XB, BE-RF, Collaboration,
NCNR Poland ?

25. Task description Task What is planned Who is involved Injector design
Beam dynamics design and optimization of the full injector
EV/BP, BE-ABP; Shahin, Avni, CEA-CESTA
SHB
SHB design, built and test prototype, 500 MHz power source
EV, BE-RF; Hamed, MME
Diagnostics
Study BPM and profile monitor for DB, prototype ?
TD, BE-BI, Thibaut, Adam, Alfonso
Electron source
Design, prototypes, test
EV, BE-RF + Collaborations
SLAC, CEA-CESTA, Steffen, Mohsen, MME
Gun test area
Revive LIL-GTF to allow gun testing, HV-power supply
EV, BE-RF, Steffen, Stephane, Lukas, Alexandra,
CEA-CESTA (HV-PS)

26. Space
Gun test area:
former GTF available, Bldg. 162-R-004/008, needs some refurbishment
1 GHz test stand:
Aim to share high power test stands in the rf group, possible candidate sides (~50 m2 needed): Bldg. 112 (LHC), 150 (CLIC), 152 (Linac4)

27. Gun geometry
aim for modular design
Typical example

28. DB-accelerator structure
RF-design existing,
next steps: mechanical design and prototype
Collaboration with National Center for Nuclear Research in Poland to built a prototype under preparation
Input and output coupler design finished
Correct match, input reflection < 30 dB.
(red and green: two different geometries; red is final)
Rolf Wegener