Linac 4High Power RF

O. Brunner & N. Schwerg

• Installation• Phase adjustment campaign

• High power equipment• Procurement of “auxiliaries”• New 2.8 MW klystrons• LEP klystrons

Summary

Installation (1)

• Klystron hall:• WG Phase 1 completed• Circulators, RF loads• Water distribution• Klystron racks

Installation (2)

• tunnel:• WG Phase 2 completed• In process: phase adjustment

Phase adjustment (1)

• The distance between the cavities (time of flight of particles) defines the phase difference required between the two RF channels

• Adjustment procedure• Measure the actual ΔΦ (i.e. WG electrical length)• Modify WG distribution such to get ΔΦ ≈ 20˚• Insert a phase shifter(0 - 60˚) in one arm for fine adjustments• Precision of measurements: ≈ 100 ps (≈ 10˚) (circulator comp.: ≈ 100 ps (≈ 10˚))

klystron circulatorsmagic T cavitiesWG

Phase adjustment (2)

=> All circulators to be moved (except for PIMS B C & PIMS C D)

DTL2.1

DTL2.2

DTL 3.1

DTL 3.2

CCDTL1

CCDTL2

CCDTL3

CCDTL4

CCDTL5

CCDTL6

PIMS B

PIMS C

PIMS D

PIMS E

PIMS F PIMS G

PIMS H PIMS I PIMS J PIMS K

PIMS L PIMS M

Measurement (deg) Not done 95 266 285 164 190 228 304 279 158 76Requirement (deg) 0 0 24 4 348 217 218 217 216 215 215(Alessandra)

Shift circulators by -129 -383 -450 281 11 17 -116 -73 62 204(mm)

• ”heavy procedure”• less posts in WG system -> reduces the risk of arcing

High Power equipment: "auxiliaries“(1)

• New circulators: contract in preparation (ATF (DE)) (≈ 500kEuros)

• RF loads: second batch delivered. On time.• Klystron garages: LEP garages to be refurbished (not started)• RF drive amplifiers: proto under test• Focusing power supplies: Israeli contribution – ok• Arc detectors: proto validated• Blowers: not started• Circulator control units: to be built • Magic Tees: prototype @ CERN. Order placed• Phase shifters: proto validated

High Power equipment: "auxiliaries“(2)

• Gun tanks: in production/assembly• Gun tank equipment: resistors, heater transformer & power

supplies (TE/EPC)

New 2.8 MW klystrons (1)• Orders were placed in 2011 with CPI and Thales

• 4 klystrons each• CPI: first klystron delivered in July. Successfully tested and

validated in September.• Thales: first klystron presently under tests at the factory

(expected delivery: end of Oct.)

• Delivery schedule• CPI & Thales:

• second klystron in January’13,• all four klystrons before Fall ‘13

New 2.8 MW klystrons (1)• CPI klystron

Name Serial No Manufacturer Year Accumulated HV hours Max RF fwd (CW (MW)) Beam Perveance (uP) Gun Perveance (uP) I filament (A) I foc1 (A) I foc2 (A) remarks

Alison 17-9835 EEV 1998 6 142 1,30 0,658 1,795 22,6 6,28 8,15 B112

Diana 06-9346 EEV 1993 11 931 1,30 0,688 1,654 24,1 6,26 8,15 Elisabeth 14-9748 EEV 1997 9 628 1,30 0,637 1,714 23,0 6,05 8,29

Janet 18-9922 EEV 1999 3 488 1,30 0,656 1,650 23,7 6,60 8,20 Joanne 16-9832 EEV 1998 5 752 1,30 0,642 1,620 22,9 6,20 8,30

Lynn 12-9725 EEV 1997 6 297 1,30 0,652 1,752 22,5 6,12 8,27 Margaret 10-9439 EEV 1994 6 990 1,30 0,648 1,676 21,6 6,16 8,68

Trena 08-94?? EEV 1994 15 372 1,30 0,689 1,706 22,5 6,07 8,42 Emilly 13-9734 EEV 1998 18 072 1,30 0,659 1,784 22,9 6,16 8,28 on loan at ESRF / will be back end of 2010

Lynda 15-9803 EEV 1998 6000 tbc 1,30 0,658 1,767 22,8 6,13 8,13 3MeV test placeSharon 04-9346 EEV 1993 17 000 1,30 0,642 1,701 24,0 6,00 8,29

Julie 07-9513 EEV 1994 18 000 1,30 0,658 1,634 23,7 6,47 8,29 Marika 04501-53 Philips 1990 12 491 1,10 0,635 1,595 22,1 9,48 … on loan at ESRF / limited to 93kV

Sonia II 75001-53 Philips 1997 12 194 1,27 0,636 1,597 22,7 7,48 … Eva 05203-53 Philips 1990 2 750 1,21 0,626 1,580 22,5 9,82 …

Helga 24801-53 Philips 1992 22 788 1,25 0,633 1,639 23,0 8,51 … Klara 44301-53 Philips 1994 22 284 1,30 0,532 1,534 22,0 7,50 … low perv! Try to increase Ifil? no cern data !

Petra 04903-53 Philips 1990 103 1,01 0,678 1,592 22,5 9,81 … Sophie 92501-53 Philips 1989 9 990 1,10 0,662 1,603 22,8 10,30 …

Agnes 89017 Thomson 1990 37 681 1,30 0,647 1,004 22,8 9,54 9,56 low perv by design / FOR L4???Cecilia 89014 Thomson 1990 12 567 1,00 0,685 1,007 1MW, max 88kV, low perv

Elia 89028 Thomson 1992 18 758 1,30 0,635 1,550 22,0 10,00 9,80 SM18Mado 89008 Thomson 1986 11 110 1,00 0,64 1,020 1MW, max 88kV, low perv

Therese 89037 Thomson 1994 18 435 1,30 0,636 1,615 22,600 9,74 9,74 Yvonne 89005 Thomson 1985 7 316 1,00 0,636 1,020 1MW, max 88kV, low perv

Pauline 89015 Thomson 1990 2 590 1,30 0,658 1,571 22,6 9,56 9,79 on loan at ESRF

Anita 89032 Thomson 1993 ?? 1,00 0,678 1,589 20,1 9,73 9,79 on loan at CEA SACLAY

Marlene 89009 Thomson 1987 9 000 1,00 0,681 1,010 1MW, max 88kV, low perv / on loan at CEA SACLAY

Marianne 89010 Thomson 1987 30 000 1,00 0,658 1,060 1MW, max 88kV, low perv

Chantal 89003 Thomson 1984 18 000 1,00 0,692 1,005 1MW, max 88kV, low perv

EEV

(12)

Phili

ps (4

)Th

omso

n (3

)

LEP klystrons: what de we have?

19 “eligible” LEP klystrons

LEP klystrons: what do we need for L4?

• we need klystrons that can produce > 1.3 MW

• we need klystrons that can be run at different working points• The LEP klystron were designed and tuned to reach optimum efficiency (>65%)

when operated at well defined operating working points (HV, Icat, drive power, impedance seen by klystron, etc)

• The klystrons suffer from instabilities when operated under different conditions

1.3 MW

output power

How do we test the LEP klystrons ?

• DC power settings: 108 kV, 22 A• Increase klystron power as a function of:

• Circulator compensation current (impedance change)• Phase variation (to mimic the beam passage)

• Detect at which output power the instabilities occur

klystron circulator

RF load

RF load(Cu cavity)Phase shifter

Pfwd Prfl

LEP klystrons performance results

-16 -14 -12 -10 -8 -6 -4500

700

900

1100

1300

1500

1700

Icirc = 0.11 AIcirc=0,42Icirc=1.5 A

Generator Level in dBm

Pow

er K

lyst

ron

forw

ard region of instabilitiesJoanne: 1300 kW

Emily: 1010 kWAlison: 1145 kWJulie: 1050 kW (now dead)Lynda: 1100 kW (3 MeV)Elia: < 1000 kW (SM18)

LEP klystrons: what can we expect?

• 5/12 EEV tubes tested:• one is very good :1300kW• others are limited to about 1100 kW or less (one died after the

test)

• Phillips & Thomson tubes are known to be even more prone to oscillations than EEV klystrons• 1/7 tested: < 1000 kW

Question: can one dream of getting significantly more than about 1 MW

per LEP klystron ? (in the required operating mode)NO !

Conclusions (1)• Installation:

• In progress• Phase adjustments in progress – heavy duty, crucial for future

reliability• Adjustments: ≈ 10˚

• High power equipment & auxiliaries• Preparation is ongoing• All “big contracts” placed (new circulators: in preparation)• 3 operational test places (B112, 3MeV, SM18)

• New 2.8 MW klystrons• Some delays• First CPI klystron successfully tested and validated at CERN• All klystrons shall be delivered before Q3 2013

Conclusions (2)• LEP klystrons

• Preparation and test in progress (slow down to be expected with the departure of Nikolai!)

• 1/3rd of the LEP klystrons have been tested:• All are capable of more than 1.3 MW peak power (for well defined WP, as

expected!)• All (except one) are unstable in the region 1 – 1.3 MW (as expected!)• Despite all efforts made instabilities could not be suppressed/reduced • One tube died after 6 months of testing: vacuum leak in RF input connector

Stability maps (measured according to the L4 mode of operation) show that the LEP klystrons modified for Linac4 are limited to 1 – 1.1 MW

• We need clear instructions from Project Leader:• Do we continue spending CERN resources on this effort?• What is the strategy for klystron installation (Do we install them? Which

klystron at which position? Is there a power limit?)• How many additional 2.8 MW klystrons that must be ordered ?