Nextef Status of high gradient experiment

May 13-15, 20082nd Collaboration meeting on X-band Accelerator Structure

Design and Test Program

T. Higo, KEK

Nextef progressEstablishing power generation and transport in 2007

080513-15 22nd collaboration meeting on X-band

Nextef inside shield roommost basic components are now in line.

080513-15 32nd collaboration meeting on X-band

Nextef planning5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

2008 2009

Establish system with KX03

T18_VG2.4_Disk #2

TD18_VG2.4_Quad

TD18_VG2.4_Disk

T18_VG2.4_Disk #3

T18_VG2.4_Disk #4

?????

C-band test at same place

2008/5/13-15 42nd collaboration meeting on X-band

What are needed for Nextef

• Enough power, 55MW, 300ns at accelerator structure, CLIC_VG1, for 100MV/m

• Square RF pulse with variable width• Operation and each RF pulse analysis at 50Hz• Stable operation with BRD < 1BD/hr at most• Proper control program based on the well-

defined processing protocol• Identification of breakdowns, distinguishing

either at structure or outside080513-15 2nd collaboration meeting on X-band 5

Nextef Nominal RF power line

080513-15 2nd collaboration meeting on X-band 6

Two klystrons

ACC Structure

Low loss waveguide

2-klystrons 120MW, 300nsklystron—3dB 2.3m3dB— LLWG 1.5mLLWG 5mLLWG—ACC Str 5.0mWR90 flanges ~36sets*7mm SUS

Loss Kly.Str. ~23%Delay ~ 50ns

S+N

ACC-IN

Shape rise and fall and flat top 2mV / 89mV

= ±0.4mW / 11mW = ±4%

Base line jitter or actual?

S+N

S+N

ACC-IN

ACC-Refl

S+N_refl

Refl_load

Refl_load

Nextef operation without structure RF shape at 50MW, 300ns, 50Hz

080513-15 72nd collaboration meeting on X-band

Refl. From load

Nextef recent typical operation

Blue ~ ACC-IN[MW], Pink = Load Vacuum, Green = Combiner vacuum

Rarely but sometimes vacuum jump near combiner 3dB, with big reflection to klystrons

Stable operation at 50MW level

Load vacuum jump with reflection from load

080513-15 82nd collaboration meeting on X-band

Readiness of components• Nextef: Refer to Matsumoto’s talk• Klystrons are tested at 60MW for 300nsec pulse,

which makes the combined power of 120MW. • 3dB hybrid or WR90 waveguide components are

sometimes arcing at 50MW level now. This needs to be conditioned out or identified to distinguish from the events due to accelerator structure.

• Loads are subject to damage due to high pulse energy operation. Proper loads are to be used for the loads downstream of accelerator structure.

080513-15 2nd collaboration meeting on X-band 9

Nextef: Nominal observables along waveguideSLAC 3dB

ACC structure

Lounine Load(based on SLAC design)

Ohtsuka Load

Guard window TE01-type

IP 30l/s

WR90

DC made by BINP

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F & Rs

T

VAC

Ra

Beam-line setup

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GVGVPM PMAM

Sl i t

FC

EH

MC

E

E

I P

Louni nel oad

Otsukal oad

DC

I P

I P

I PH

H

GW

DC

VAC

I nsulVAC

I PDC H

H

Vari an I P

187

KX03

H H

HE H

425

FC

I P

Load

Vari anI P

Q-mass

WC WCFC

FC

Rack

VAC DC1260

Nextef Beam l i ne and wavegui de conf i gurati on

5000

3000

500500

500

230

Nextef: observables along beam axis

080513-15 2nd collaboration meeting on X-band 12

GVGVPM PMAM

Sl i t

FC

E

E

I P

Louni nel oad

Otsukal oad

DC

I PH

VAC

I nsulVAC

I PDC H

H

Vari an I P

187

KX03 425

FC

I P

Load

Vari anI P

Q-mass

WC WCFC

FC

VAC DC

230

FCFCFCQmass

PM PMAM

GVGVACC str

Preparation status of sensors• RF pulse: crystals

– Combined, ACC-input are being monitored as feed RF power.– F, Rs, Ra and T will be detected with crystals. Each pulse will be analyzed with 7000 series Tektro

oscillo. Oscilloscope data taking is under development at KT-1.

• VAC : cold cathord gauges– CCG monitors are working at various places of WR90 and two points of beam line

• Dark currents: Faraday cups, analyzer magnet and profile monitors– DC current measurement wit FC is our typical.– Transient response of FC is yet to be confirmed.– AM should work without problem.– The response of profile monitor is not checked after many years idling.

• Acoustic sensors– Sensors are those from SLAC and used at XTF.– VME modules are under preparation for operation.

• Photomultiplier and scintillator– A few lead-shielded sets are prepared.

• Q-mass – Operation should be checked.

080513-15 2nd collaboration meeting on X-band 13

Various detection tools are to be integrated into Nextef control system

System control PCPython, Linux

DPO7054(1GHz, every pulse)

VME Acoustic (SLAC)

Mod. PLC

Acc PLC

CCG

RF crystal

Various signal

CT

FCAM

Data storageKEKB Inj. control

DL7480(500MHz)

History 4MW/ch

Modulator

KlystronLLRF

FPGA (100MHz)

S/H & DC Amp

Discri

Acoustic

INTLK Safety

Etc.

X-ray

Etc. Etc.

Etc.

X-ray

Now b

eing

prep

ared

Pictures are

recorded now.

Digital data should

be recorded.

Buy for Nextef?

TDS3034B (300MHz)TDS3054B (500MHz)

Nextef to be done for breakdown detection system

• Tektro 7054 pulse-to-pulse analysis– Take experience at KT-1– Establish the threshold and other parameters

• RF pulse at all points– Identify the breakdown position in Nextef system– Digital data taking and analysis as needed.

• VME modules– Restart operation program similar to XTF– Use as positioning of arc in the system or in the structure.

• FC, AM, PM, PMT, Q-mass operations– Basic performance should be confirmed. With actual signal or with other

source?

• Red-marked items should be from the beginning of CLIC_VG1 test.2008/5/13-15 152nd collaboration meeting on X-band

Conclusion • Nextef power rating is now ~50MW, 300ns, 50Hz level with

less than 1BD/hr.

• We need to establish the detection system in May with KX03.– In breakdown detection and analysis at the input power level of

50MW or more.

• We want to start CLIC_VG1 before summer shutdown of KEKB. – Some incompleteness of the system should be tolerated, as long as

essential features, such as power evaluation, processing protocol and identification of breakdown, are confirmed.

• We try to operate the Nextef as effectively as possible within the KEK regulation. – Hopefully run during shutdown but we admit it not easily be realized.

080513-15 162nd collaboration meeting on X-band