CLIC DB injector front end update on the work

package

Steffen Döbert, BE-RF

Description of the work package

Drive Beam Klystron status

Overview of the ongoing work

Collaborations

Outlook, planning

CLIC DB injector front end update on the work

package

Steffen Döbert, BE-RF

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

CLIC DB front end

Gun, sub-harmonic bunching, bunching, three accelerating structures,5 long pulse klystrons and modulators, diagnostics, beam line

Gun SHB 1-2-3

PB Buncher Acc. Structures

IOTs ?, 500 MHz

Modulator-klystrons, 1 GHz, 15 MW

~ 140 keV ~ 12 MeV

Diagnostics

~ 3 MeV

CLIC DB front endHardware R&D

Reduced scope: Gun, sub-harmonic buncher, rf-unit, diagnostics, injector design

Gun

SHB 1Acc. Structures

500 MHz

Modulator-klystron, 1 GHz, 20 MW

~ 140 keV Diagnostics

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

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

20 MW L-band klystron for CLICGun topology scaling scenarios

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 (>150 000 hours) life time and operated at a reasonable (164 kV) cathode voltage. This choice also may be the most cost efficient.

Tentative klystron parameters

PARAMETER VALUE UNITSRF FrequencyBandwidth at -1dBRF Power:Peak PowerAverage PowerRF Pulse width (at -3dB)HV pulse width (at full width half height)Repetition RateHigh Voltage applied to the cathodeTolerable peak reverse voltageEfficiency at peak powerRF gain at peak powerPerveanceStability of RF output signal at nominal working pointRF phase ripple [*]RF amplitude ripplePulse failures (arcs etc.) during 14 hour continuous test periodMatching load, fundamental and 2nd harmonicAverage radiation at 0.1m distance from klystronOutput waveguide type,

999.516≥ 1  ≥ 2015015016550tbd, ≤ 180 tbd65 ≥ 67 ≤ 70tbd, > 48tbd ±1 (max)±1 (max)< 1-2tbd< 1WR975 pressurised

MHzMHz MWkWμsμsHzkVkV%dBμA/V1.5

 RF deg% VSWRμSv/h2-3 bar

Status: Preparation of call for tender

Klystron Modulator and test stand

Status: see presentation from D. Aguglia

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)

• 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

Sub-harmonic bunching system

Status: RF design existing, mechanical design advanced,Next: launch prototype (in aluminum ?)

Power source: 500 MHz, 34-82 kW, wide band (60 MHz) sources needed for fast phase switching. Started to discuss with industry.

Hamed Shaker, see IPAC paper

DB injector review and optimization

Shahin Sanaye Hajari, see as well IPAC paper

Final phase space at 50 MeV after re-optimization of the injector with realistic rf parameters, 4% satellites, good longitudinal phase

space

DB injector review and optimization

Total losses reduced from 30% to 11%

Shahin Sanaye Hajari, see as well IPAC paper

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

Gun simulationsUsing EGUN

-5 -4 -3 -2 -1 0 1 2 3 4 5-15

-10

-5

0

5

10

15

R [mm]

Ang

le [m

rad]

e ~ 12 mm mrad

Gun simulationsEmittance vs voltage

100 120 140 160 180 20010

15

20

25

gun voltage [kV]

rms

emitt

ance

[mm

mra

d]

3 4 5 6 7 8 9 10 11 12 13 1410

15

20

25

30

35

40

45

50

55

60

gun current [A]

rms

emitt

ance

[mm

mra

d]

16Centre d’études scientifiques et techniques d’Aquitaine (CESTA)29/01/2013

Ez

Er

B

Ez

Er

B

Typical MAGIC snapshot: particle positions in r-z

Typical MAGIC snapshot: kinetic energy of particles along z

Contour plots of field components at t=35nsJacques Gardelle

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

Fabrication Test

Modulator design CESTA

Prototype Prototype at CERN

Concepts for HV deck electronics

Design of pulser electronics

Fabrication and tests

Ready for use

DB-Gun strategy and planning

Beam diagnosticsGas Jet Monitor

adam.jeff@cern.ch

• 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 Pumping Pumping

Collection chamber

Gas source

Shaping

Adam’s Summary 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

adam.jeff@cern.ch

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

Outlook,Rough planning, milestones

Task 2013 2014 2015 2016

Gun test areaprepare gun test area

ready for first tests

testing with HV modulator testing

Gun design Prototype, first tests gun tests  

SHB Buncher fabricationtesting low power testing high power  

500 MHz power source specifications purchase needed for test  

1 GHz structurespecs, mech. design construction low power test

high power test

Diagnostis design design tests in gun area ?  

LLRF specs fabrication+testready for klystron test  

1 GHz klystrons tender, contract Design reviewReceive first prototype Klystron 2

1 GHz Modulator R&D R&D Receive first MDK MDK2

1 GHz rf test stand specs, location prepareReceive MDK, klystron

Ready for testing

RF stability Measure CTF3, DESY? Measure SLAC ?

END

CLIC DB injector specifications

Parameter Nominal value UnitBeam 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 100 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 0.1 %

Allowed satellite charge < 7 %

Allowed switching time 5 ns

Task description

Task What is planned Who is involvedKlystron Tender, Purchase, Follow up,

receptionEV, 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, LucaTD, 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 ?

Task description

Task What is planned Who is involvedInjector 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 + CollaborationsSLAC, 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)

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)

Gun geometryaim for modular design

Typical example

DB-accelerator structure

Input and output coupler design finishedCorrect match, input reflection < 30 dB.(red and green: two different geometries; red is final)

RF-design existing, next steps: mechanical design and prototypeCollaboration with National Center for Nuclear Research in Poland to built a prototype under preparation

Rolf Wegener